Camera eyes in vertebrates, cephalopods and other animals
Camera eyes are superb optical devices, so it is not surprising that they have evolved several times. But why, of all animals, in the brainless jellyfish? Or for that matter in a slow-moving snail?

Octopus and other cephalopods: convergence with vertebrates
What could be more different from us than the alien-like octopus? Hold on. Look it in the eye and think again.

Elastic proteins
What do rubber bands and fleas have in common?

Camera eyes of cephalopods
The remarkable similarity between the camera eyes of cephalopods and vertebrates is one of the best-known examples of evolutionary convergence.

Teeth in aquatic reptiles
Aquatic reptiles tend to display one of three dentition types, well adapted to either seize and slice large vertebrate prey, pierce and gouge slippery fish, or entrap small prey such as crustaceans.

Octopus arm function
If you want to see a truly remarkable example of convergence, then present an octopus with a piece of food and have a high-speed camera ready…

Defence in frogs: toxins and camouflage
The many striking examples of convergence most famously include the case of mimicry, but the question of defence also extends to the use of toxins (and venoms), such as alkaloids, where we also find molecular convergence.

Burrowing: from worms to vertebrates
Quite a few adaptations are useful for burrowing into the soil. So it is not exactly surprising that they have evolved several times...

Beak structures in reptiles and birds
Among reptile taxa with beak structures, we find several cases of convergent evolution, for example between turtles, Uromastyx lizards, a number of herbivorous dinosaurs and the tuatara (Sphenodon) of New Zealand.

Electroreception in fish, amphibians and monotremes
From an evolutionary point of view, electroreception is particularly intriguing as a sense modality that has been repeatedly lost and reinvented again.

Frogs with fangs
Teeth have clearly evolved a number of times, and one of the more interesting curiosities is found in the amphibians, notably in the frogs where several groups have independently evolved fangs.

Tongues of chameleons and amphibians
[p]Convergence in tongue function represents repeated morphological exploration within different lineages made possible by loss of an ancestral functional constraint[/p]

Worm-like body form
Man is but a worm, but so are many other vertebrates...

Crystallins: eye lens proteins
Whereas typically technology demands furnaces, so that the glass for a lens is produced at hundreds of degrees Celsius and then requires most careful grinding, so nature calls upon proteins known as crystallins.

Simple tool use in owls and cephalopods
Burrowing owls place pieces of collected dung. These attract insects such as beetles that are then eaten by the owls.

Vibrational communication in insects and spiders
Some spiders have evolved a most remarkable method of capturing other spiders – they imitate the vibrations of insects caught in their victim’s web. And this is only one of numerous intriguing examples of vibrational communication in arthropods…

Vibrational communication in mammals
Kangaroo rats drum their foot on the ground upon encountering a snake. Why? Read on for this and many other fascinating examples of vibrational communication in mammals…

Penis form in mammals, turtles, birds and octopus
The specific case of a penis with a hydrostatic structure, as well as an array of collagen fibres that allows both expansion and guards against aneurysms, has evolved in a strikingly convergent fashion in mammals and turtles.

Love darts in slugs, snails and annelid worms
The curious habit of stabbing their partners with sharp calcareous (or chitinous) darts during courtship and prior to actual copulation has understandably attracted considerable attention.

Dental batteries in ceratopsians, hadrosaurs and elephants
The dental batteries or 'pavements' of ceratopsians and hadrosaurs evolved independently, and yet the dentition of several more distantly related animals also converges on their highly adapted tooth form.

"Colour vision" in Firefly squid
The Japanese firefly squid (Watasenia scintillans), which inhabits the deep ocean, has three visual pigments located in different parts of the retina that are likely to allow colour discrimination as they each have distinct spectral sensitivities.

Transparent tissues: eyes, bodies and reflective surfaces
Read on if you want to know about the numerous animal equivalents to the invisible man...

Haemocyanin in arthropods and molluscs
The degree of similarity between the active sites in arthropod and molluscan haemocyanin has been called “remarkable” and “startling”, but actually suggests that wherever in the universe life employs copper for aerobic respiration it will call upon haemocyanin.

Succulent desert plants
Classic examples of convergence in desert plants include the so-called 'stem succulent' cacti in the Americas and cactus-like Euphorbia species in Africa and South Asia, and also the striking similarity between 'leaf succulent' Agave and Yucca of the Americas and Aloe and its close relatives in Africa.

Crustaceans: insights into convergence
Whilst predominantly marine, quite a number of crustaceans have invaded freshwater habitats and even more interestingly a few demonstrate terrestrialization, effectively freeing themselves from their aquatic ancestry.

Ants: insights into convergence
Trap-jaws, silk and agriculture – just a few examples of convergence in the arguably most successful group of insects, the ants…

Developmental genetic pathways to convergence
At first sight there is a fairly simple dichotomy between convergent features that have effectively the same genetic basis, and those where the same feature emerges but the underlying genetics are different. The former, however, is somewhat more complicated...

Ecology and cosmetics in vultures
Vultures are not only charistmatic birds in the popular imagination, but are strikingly convergent, especially regarding feeding types...

Swimming and thermoregulation in sharks and tuna
Thunniform swimming depends on a large, lunate tail that is joined to the rest of the body via a narrow peduncle. Whilst the tail flicks backwards and forwards, so propelling the animal, the rest of the body hardly moves sideways.

Hummingbirds and hummingbirdoid moths
Like other birds hummingbirds are warm-blooded, but so independently are the hawk-moths, which like a number of insects have evolved thermoregulation.

Woodpeckers and woodpecker-like birds and mammals
You think woodpeckers are unique? Consider the ovenbirds. Or even the curious aye-aye.

Agriculture in ants: leaf-cutters (attines) and non-attines
In some species, special squads leave the nest early each day, ascend the tree-trunks and then spend hours cutting out pieces of leaf that are dropped to other units on the ground.

Beetles: insights into convergence
The beetles are probably the most diverse animal group on earth, so it is not at all surprising that they provide many fascinating insights into convergence.

Zinc in teeth
On land, we find the employment of zinc to reinforce feeding structures in the fangs of spiders, and also in a variety of insect groups.

Agriculture: from ants to dugongs
Human farmers tending their fields are a familiar sight. But don't forget about those fungus-farming termites or the fish with a garden of algae…

Sleep in animals
Suffering from insomnia? Fruit flies do as well...

Strepsipterans: convergent halteres and eyes
Strepsipteran females spend their whole life inside a wasp. The males are rather more exciting, particularly in terms of convergence…

Chloroplast and mitochondrial plastid origins
Not only are there intriguing parallels in the story of gene loss in chloroplasts and mitochondria, but there is also the re-invention of bacterial pathways, such as oxidation of quinols.

Dolphin communication, cognition and sociality
Dolphins are one of the most intriguing sources of evolutionary convergence, having cognitive abilities that seem to find many parallels in the great apes, and rather remarkably even extend to tool use.

Desert plants with succulent stems
Fleshy, succulent stems have evolved in several distantly related desert plant families, including cacti, certain species of Euphorbia and two genera of the family Asclepiadaceae, Hoodia and Stapelia.

Electric fish: insights into convergence
Ever seen an electric eel in an aquarium? Don’t dare putting your hand in the tank...

Teiid lizard dentition: convergence with other reptiles, mammals and fish
Teiids are skink-like lizards whose members show a stunning diversity of tooth types, providing rich evidence of convergence within the teiids themselves, in distantly related reptile groups and even in certain mammals and fish.

Cavitation: bubble formation in plants, reptiles and shrimps
The formation of bubbles in a fluid is known as cavitation. Typically this occurs at low pressures, and is perhaps best known in the xylem of plants where embolisms can be destructive to the surrounding tissues.

Complex tooth occlusion in notosuchid crocodiles and tritylodonts (proto-mammals)
Two unusual Early Cretaceous crocodiles provide a shining example of convergence, as their dentition parallels that observed in a group of advanced proto-mammals called tritylodonts.

Sap feeding and honey-dew production in insects
Interestingly, it has now been shown that the saliva of the aphids has an analogue to the anti-coagulant properties of blood suckers, subverting the wound repair mechanism of the plant.

Sabre-toothed cats and marsupials
Marsupials with giant fangs? Yes, not all of the extinct sabre-toothed cats were actually cats…

Tool use in birds
What animals can drop stones into a water-filled tube to bring floating food within reach or bend wire to form a hook? Obviously chimpanzees? No, New Caledonian crows have evolved sophisticated tool use too.

Baculum (penile bone) in mammals
Ouch!! Gentlemen, fancy a bone in your penis? Seems a bit risky, given it could fracture during copulation. Even our near ancestors had such a bone. It has probably evolved several times, but what is its function?

Carbonic anhydrase in vertebrates, plants, algae and bacteria
Carbonic anhydrase is extremely convergent and may have evolved as many as six times. The most familiar variants are α, β and γ carbonic anhydrases.

Gut fermentation in herbivorous animals
Ever tried eating a newspaper? Don't. Plant cell walls contain cellulose, which is notoriously difficult to digest. Considering that all vertebrates lack the enzymes to attack this polysaccharide, how do so many of them manage to survive on a plant diet?

Tetrodotoxin
Not many foods served in a restaurant can kill you, but pufferfish is the exception. Tetrodotoxin, the toxin responsible for such culinary fatalities, reveals a fascinating story of convergent evolution...

Birds: insights into convergence
Intriguing ecological and morphological parallels can be found among the Neoaves. Many of these forms were initially believed to be each other's closest relatives, but are now widely recognised as classic examples of convergence. Think how similar swifts and swallows are, but they are only distantly related.

Venom and venom fangs in snakes, lizards and synapsids
Although the evolution of snake fangs itself provides us with a window on convergence, the presence of fang-like teeth in lizards, therapsids and mammals provides an even broader and more remarkable perspective.

Feeding in snakes and lizards
The Turtle-headed sea snake feeds on small eggs and its feeding shows intriguing similarities to the way lizards forage, and herbivorous mammals graze and browse.

Intelligence and cognition in birds
House sparrows are known to gain access to shopping malls by flying in front of sensors that operate sliding doors, whilst herons have been shown to be adept fishers using baits and lures.

Enzymes: convergence on active sites and reaction types
Enzymes make the world go round, each an evolutionary marvel - and convergent.

Lysozyme
Lysozymes are common antibacterial enzymes that protect our eyes and nose from infection, but some animals have recruited them for a rather different purpose...

Bacterial carboxysomes (and other microcompartments)
It is now clear that the cellular construction of at least the eubacteria is more complex than realized, and includes organelle-like structures known as microcompartments, of which the best known are the carboxysomes.

Biological uses of silk: from webs to ballooning
What material is so versatile that it can be used for capturing prey, building nests, communication and even cleaning? The answer: that most remarkable of biomaterials - silk.

Spitting in spiders and velvet worms
Scytodid spiders forcibly eject a mixture of saliva, silk and venom in a glutinous mass over a distance of c. 1cm to entrap prey.

Mussel attachment and the Pinna byssus
It is clear that the Pinna byssus has unusual properties in comparison to its equivalent in the bivalve mussel, and is conspicuously different in terms of crystallinity.

Viviparity in lizards, snakes and mammals
“In over 100 lineages of […] squamates, the oviduct has been recruited for viviparous gestation of the embryos, representing a degree of evolutionary convergence that is unparalleled in vertebrate history.” D. G. Blackburn (1998) Journal of Experimental Zoology, vol.282, p.560

Silk production and use in arthropods
Remarkably, fossil silk is known, especially from amber of Cretaceous age. Material includes both silk with trapped insects, possibly from an orb-web, and strands with the characteristic viscid droplets that are the key in trapping prey.

Adhesive pads: from geckos to spiders
In terms of adhesive pads we find they have a remarkably wide distribution evolving in at least four distinct groups, including members of the reptiles, amphibians, arthropods and mammals, with tentative parallels in sea urchins.

Innate and adaptive immune systems
A vile cough, soaring temperature? When attacked by nasty microbes, our immune system comes in handy. Surprisingly (or not), plants have come up with a very similar solution to dealing with pathogens, but independently...    

Camera-like eyes in arthropods
Arthropods are famous for their compound eyes, but some groups have had a fair crack at evolving the optically superior camera eye…

Telephoto eyes in animals
Pursued by the paparazzi? Watch out for those animals equipped with telephoto lenses...

Scanning eyes in molluscs and arthropods
Some sea snails have a linear retina. What a hopeless arrangement, to see the world through just a narrow slit! Not quite, because they have come up with a rather intriguing trick to extend their visual field - and it's a trick too good to use only once.

Camera eyes in gastropod molluscs
The fast-moving cephalopod molluscs are famous for their camera eyes, but why on earth have gastropod snails, which are not exactly known for their speed, evolved this superb visual organ at least four times?

Compound eyes in ark clams
Read on if you want to know more about bivalves with burglar alarms…

Pinhole eyes in Nautilus and giant clam
The pinhole eye has evolved not only in the Pearly Nautilus, but also in another group of molluscs, the bivalves and specifically the giant clams (Tridacna).

Camera eyes in alciopid annelids
There is a striking example in the group known as the alciopids, which are pelagic polychaetes. The similarity of their camera eye to the vertebrate eye has attracted considerable comment.

Compound eyes in sabellid annelids
Compound eyes have evolved convergently in the annelids, notably amongst the sabellids, where they evidently serve as an optical alarm system.

Reptile dentition: convergence on complex occlusion
Some reptiles have transverse chisel-like teeth for slicing, and others have teeth bearing projections ('cusps') that interlock and slice or grind tough food. In each case evolutionary parallels are clear both within and outside the reptiles.

Compound eyes in arthropods
It is clear that amongst the arthropods as a whole the compound eye has evolved at least twice, and possibly even more times.

Wire plants, moas and elephant birds
Madagascar and New Zealand were once home to giant herbivorous birds. And the plants have not forgotten...    

Lipocalins for milk and pheromone transport
Lipocalins are proteins that bind to and transport small hydrophobic molecules such as lipids and steroids, and have been associated with biological processes such as milk production, pheromone transport and immune responses.

Vision in echinoderms
Among brittlestars and sea urchins we find visual systems that in some ways rival the arthropods in the form of compound eye-like structures.

Corneal nipple arrays in insect eyes
Anti-reflection coating? Not only on mobile phone displays, but also on insect eyes...

Hearts in cephalopods and vertebrates
There is a striking convergence between the aorta of the cephalopod and vertebrate heart, notably in its structure and the employment of elastic proteins.

Mitochondrial lens formation in flatworms
In some of the flatworms (platyhelminthes) the lens is formed from mitochondria, and it is intriguing to speculate whether a mitochondrial enzyme has been co-opted to provide a crystallin.

Ancient opsins and vision in extinct animals
Spectral tuning of the eye generally depends on key substitutions of amino acid sites in opsin proteins.

Loss of olfactory capacity in primates and cetaceans
It is widely thought that reduced olfactory capacity in apes is linked to the development of acute vision, especially trichromacy.

Taste in arthropods and mammals
The ability to taste is obviously an essential component in the life of any animal, both to assess the potential quality of food, its nutrient capacities and also to detect toxins or other dangers.

Infrared detection in animals
Some snakes are famous for 'seeing' infrared, but did you know that their heat-sensing abilities are rivalled by some beetles that can detect forest fires over considerable distances?

Infrared detection in snakes
Warm-blooded rodents watch out! There are heat-sensing predators on the prowl...

Desert plants with succulent leaves
Perhaps the most striking case of convergence among leaf succulents occurs between Agave and its relatives Yucca and Hesperaloe in the Americas and Aloe and its relatives (e.g. Haworthia and Gasteria) in Africa.

Infrared detection in insects
Whilst infrared detection is probably best known in the snakes (where it has evolved twice), in point of fact in terms of convergence the insects provide by far the most striking example.

Venom in mammals (and other synapsids)
Beware the venomous shrew! Yes, venomous. And convergent on some formidable lizards...

Olfaction: insights into convergence
Although olfaction is very widespread, there is abundant evidence for repeated convergence of key features, strongly suggesting that there really is an optimal solution to detecting smells.

Trichromatic vision in mammals
Who has not enjoyed the splash of colour in a market: gorgeous red peppers, the green of basil and what on earth are these purple vegetables over there? All thanks to trichromatic vision, another story of convergence.

Viviparity in ichthyosaurs
“For me, the fossil is a transporting piece of evidence. It shows a female ichthyosaur that died late in pregnancy or perhaps while giving birth; the baby was entombed with its mother in the mud.” J. Rennie (2000) Scientific American, vol. 283(6), p.8

Viviparity in mosasaurs
An exceptionally preserved gravid female of the aigalosaur Carsosaurus contains at least at least four advanced embryos […] Their orientation suggests that they were born tail-first […] to reduce the possibility of drowning, an adaptation shared with other other highly aquatic amniotes” M.W. Caldwell & M.S.Y. Lee (2001) Proceedings of the Royal Society of London B, vol. 268, p.2397

Viviparity in sauropterygians
“The [fossilised] embryos are mostly in articulation and their distribution on each side indicates that female Keichousaurus hui had a pair of oviducts as in ichthyosaurs and many extant lizards.” Y. Cheng et al. (2003) Nature vol. 432, p.383

Mammal-like placentation in skinks (and fish)
“Only two types of vertebrates [have] evolved a reproductive pattern in which the chorioallantoic placenta provides the nutrients for fetal development. One is [...] the eutherian mammals […], and the other, a few lineages of the family Scincidae.” A.F. Flemming (2003) J Exp Zool 299A 33-47

Anolis lizard ecomorphs
“A classic example of convergent evolution is the set of Anolis lizard ecomorphs of the Greater Antilles.” – Langerhans, Knouft & Losos (2006) Evolution, vol. 6, p.362

Parthenogenesis in Australian lizards and insects
“Evidence on the origin and spread of the two best-studied cases of parthenogenesis from the Australian arid zone, the grasshopper Warramaba virgo and the gecko Heteronotia binoei, suggests that they evolved in parallel.” – Kearney et al. (2006) Molecular Ecology vol. 15, p.1743

Drinking adaptations in desert lizards
Both Moloch horridus and [...] Phrynosoma cornutum have the remarkable ability to transport water over their skin’s surface to the mouth where drinking occurs. Sherbrooke et al. (2007) Zoomorphology, vol. 126, p. 89

Ecological adaptations in Moloch and Phrynosoma lizards
Lizards of the genera Phrynosoma and Moloch have been considered a classic example of convergent evolution J. J. Meyers & A. Herrel (2005) The Journal of Experimental Biology, vol. 208, p. 114

Sand-dwelling (psammophilous) lizard ecomorphs
Desert sand dunes represent an extreme environmental setting in which selective forces have apparently generated dune ‘ecomorphs’ in six lizard families. – Lamb et al. (2003) Biological Journal of the Linnean Society, vol. 73, p. 253

Gliding reptiles
In the reptiles, different forms of skin membrane (called ‘patagia’) and in some extinct species, primitive feathers, have evolved convergently as adaptations for gliding.

Gliding mammals
Gliding mammals rely primarily on extensive skin membranes or ‘patagia’ that stretch between fore- and hind-limbs, creating a wing-like structure.

Gliding in feathered reptiles
A number of reptile species have been discovered in the Mesozoic fossil record, bearing feathers that were apparently used to support gliding locomotion, rather than true, powered flight as we see in present day birds.

Gliding in Draco lizards and tree snakes
“The agamid lizard genus Draco (consisting of the so-called ‘flying dragons’) exhibits an array of morphological traits associated with gliding.” – A.P. Russell & L.D. Dijkstra (2001) Journal of the Zoological Society of London, vol. 253, page 457

Gliding lizards, frogs and ants
Tree-dwelling (‘arboreal’) ants capable of controlled gliding do so when dislodged or threatened by predation. Gliding species include members of three disparate families: Myrmicinae, Pseudomyrmecinae and Formicinae.

Extremophiles: Archaea and Bacteria
Surely, no organism can survive in boiling water or brines nine times the salinity of seawater? Wrong - some archaea and bacteria have independently evolved adaptations to such extreme environments...

Dinoflagellate "nematocysts"
Examples of convergence within the dinoflagellates range from the evolution of a camera-like eye to stinging 'nematocysts' reminiscent of those in jellyfish.

Ink production in cephalopods and gastropods
A series of striking convergences can be found in the sea-hares (Aplysia), a group of gastropods and only remotely related to the cephalopods.  Not only do they emit ink clouds (the colour is derived from ingested red algae), but they also employ chemical cues that assist in defense.

Magnetotactic bacteria
Magnetotactic bacteria provide some excellent examples of convergent evolution.  In particular the ability to synthesize iron compounds has evolved at least twice, respectively employing iron oxide (magnetite) and iron sulphide.

Durophagy (hard prey-eating) in fish
Plenty of animals have an extraordinary capacity to crush hard prey and this has evolved independently many times in the vertebrates. If you suspect it is a durophage, watch your fingers!

Pharyngeal jaws in teleost fish
One of the great evolutionary breakthroughs in the teleost fish was the conversion of some of the elements that supported the gill bars into a second set of pharyngeal teeth that complemented the oral teeth. See how a fish becomes a snake!

Camera eyes in cubozoan jellyfish
On each of the four club-like extensions (rhopalia) near the base of the cubozoan jellyfish bell there are two camera-eyes, one pointing upwards and the other downwards.

Dandruff, Malassezia and Candida
The presence of Malassezia does not guarantee dandruff, as this fungus is commonly present on healthy skin, but it evidently central to dandruff production if other key factors support it.

Nuptial gifts in insects and spiders
Male dance flies lure females with a dead insect. Not very romantic, you might think, but it certainly does the trick. Hence, such nuptial gifts have evolved in numerous other arthropods...

Thanatosis (feigning death) in spiders and insects
Beetles that "play possum"? A rather interesting example of convergence…

Echolocation in toothed whales and ground-dwelling mammals
Given the extraordinary powers of echolocation in bats, it is not surprising that this group has received the most attention. However, they are not the only mammals to have evolved echolocation. Who invented sonar millions of years before the Navy?

Bats: Insights into convergence
Bats show a fascinating array of convergences, from echolocation to flight to nectar feeding. Vampire bats can even detect infrared radiation, while others might be able to see into the ultraviolet end of the spectrum.

Saxitoxin synthesis: from molluscs to algae
Saxitoxin has a similar molecular structure to tetrodoxin and a wide distribution amongst living organisms, with evidence that is has been recruited independently several times.

Ascomycete fungi: insights into convergence
Today ascomycetes are an extremely important group of fungi, and they take their name from the reproductive structures known as ascii.

Carnivorous fungi: a diet of worms (and other animals)
Fungi have learnt how to trap living prey, notably nematodes but also a range of other animals include rotifers, tardigrades and even springtails.

Independent eye movement in fish, chameleons and frogmouths
One of the most surprising convergences amongst animals is that seen between a small fish that lives in coral sands, known as the sandlance, and the lizards known as chameleons.

Limblessness in lizards
What's that slithering towards you? A snake? Look more closely, look convergently...

Crabs: insights into convergence
You might think of crabs mainly as food, but this group is also highly instructive in terms of convergence…

Crustacean-trapping teeth in mesosaurs and crabeater seals
The multi-lobed post-canines of Lobodon carcinophagus are a functional analogue to the long, thin cage-like teeth of Mesosaurus, as both cage and prevent the escape of small crustacean prey.

Suction feeding in fish, amphibians, reptiles and aquatic mammals
Probably everyone is familiar with the walrus, but did you know that it generates a vacuum in its mouth to suck clams out of their shells? And this is just one example of suction feeding, the feeding mode typically used by bony fish…

Hummingbirds, sunbirds and honeyeaters
One of the most well known examples of convergence among birds is between hummingbirds, sunbirds and honeyeaters, all of which are small, dominantly nectar-feeding birds.

Mushrooms and their relatives (Basidiomycota)
Mushrooms are not only tasty, but also provide numerous examples of evolutionary convergence...

Autumn leaf colouration
Autumn colours are likely to be adaptive, as the 'default' is simply to remain green up to leaf fall, and both red and yellow leaf colouration have evolved independently on many occasions in gymnosperms and woody angiosperms.

Collagen in animals and bacteria
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Moray eels
Eels masquerading as snakes sounds interesting, and that is before they go hunting with their friends the groupers...  

Explosive discharge in fungi and plants
The very rapid release of reproductive bodies is perhaps most famous in the fungi, where several methods of flinging spores at high velocity have evolved independently.

Anointing in mammals
The strategy of anointing the body with the scent of a more dangerous animal has evolved independently several times, including in rodents, hegdehogs and tenrecs.

Mimicry in fungi
Insects pollinating flowers are a familiar sight. But what happens when the "flower" is actually a fungus? Still "pollination", but now it is fungal spores. Read on to learn more about the fungi that mimic flowers...

Myelinated nerves in vertebrates, annelids and crustaceans
Myelinated nerves are an excellent biological solution and needless to say have evolved independently in several groups other than vertebrates. In each case myelination is associated with very rapid nervous conduction and often escape reactions.

"Broken jaw" - mandibular and maxillary jaw joints
At first sight having a jaw with a joint seems a contradiction in terms, but such exist and not only are obviously functional, but needless to say convergent.

Evolution of birds from feathered reptiles
Birds, in the sense of flying descendants of feathered reptiles (a more expansive group than the "true" birds in today's skies), evolved several times from within the theropods.

Dicyemids and chromidinids: enigmatic endoparasites
Dicyemids and chromidinids are tiny, worm-like or 'vermiform' creatures that typically live inside the kidneys ('renal organs') of cephalopod molluscs such as octopus, squid and cuttlefish.

Agriculture in aquatic snails
Termites and ants are famous for tending fungal gardens, but did you know that also a marine snail farms a fungus? And this is not the only example of agriculture in this group…

Echolocation in birds: oilbirds and swiftlets
The best known example of echolocating birds are the South American oilbirds (Steatornis caripensis), so called because their flesh yields abundant oil.

Pufferfish (and inflation)
Pufferfish are some of the most extraordinary fish to have evolved, especially because of their capacity to swallow water and inflate themselves to something like a football. Not only that but some representatives can be deadly to the unwary diner...

Mitochondrial genome convergences
Most likely, mitochondria have a single evolutionary origin, but that doesn't mean they are immune to convergence...

Lateral line system in fish and other animals
Some cavefish are completely blind, so how do they manage to navigate through their environment with astonishing ease?

Foam nests in animals
Nests crop up everywhere, but one made out of foam? Might not sound like a great idea, but it is. And no surprise, it has evolved several times...

Malodorous flowering plants
Several groups of angiosperms have flower structures that produce foul odours to attract pollinating insects. This strategy is convergent, being found in species as distantly related as the 'Titan arum' Amorphophallus titanium (a monocot) and the 'Corpse flower' Rafflesia (a eudicot).

Xylem vessels in vascular plants
Vessels are characteristic of the angiosperms, and yet they have evolved independently in several other groups, including the lycophyte Selaginella, horse-tail Equisetum and the enigmatic Gnetales.

Reversion from xylem vessels to tracheids
In three plant taxa that evolved in environments with frequent freeze-thaw cycles (Winteraceae, Trochodendraceae and cold desert Ephedra), vessel evolution has been reversed independently in favour of a return to a tracheid-based vascular system.

Torus-margo pits in vascular plant xylem
Torus-margo pits probably evolved once in the gymnosperms, after the split of more advanced gymnosperms from the cycads. Surprisingly, eight genera from five families of angiosperms, which are characterised by highly effective xylem vessels, have also evolved torus-margo structures.

Secondary xylem (wood) in vascular plants
Evolution of wood in plants as distantly related as lignophytes, Calamites and Lepidodendron is an elegant example of convergent evolution. Plants responded in a similar way to a need for better structural support as they diversified and increased in size.

Pressure sensitivity and the tactile sense (excluding the lateral line)
The star-nosed mole is famous for, well, its nose, but do you have any idea what these peculiar 'tentacles' are for? The answer is rather touching and, of course, convergent...

Vibrational communication in animals
What on earth could an elephant or treehoppers have in common with a seismometer?

Cichlids
Cichlids are one of the cause celebré of evolution, and rightly so because these freshwater fish show a remarkable diversity and exemplify many key aspects of adaptive radiation. But why so successful? The answer lies in the versatility of the jaws (and yes, they are convergent).

Agriculture in damselfish
Don’t be tempted to think human agriculture is unique. On many coral rocks, there are very similar things going on…

Agriculture in beetles
Think of weevils and most likely you'll think of spoiled food. But some weevils have turned to farming...

Agriculture in gall midges (Diptera)
Flies, fungi, farming - sounds interesting? Read on if you want to learn about some rather different gall midges...

Agriculture in dugongs
When you think of grazing mammals, you might envisage large herds of antelopes roaming African savannahs. Did you know that there is an equivalent in the ocean, feeding on seagrass?

Agriculture in wood wasps
The most famous hymenopteran farmers are, without doubt, the attine ants. Rightly so, but they are not the only ones...

Agriculture in marine polychaete annelids
Some polychaetes attach pieces of algae to their dwelling tube. Just for decoration? No, but for a much more substantial (and convergent) benefit...

Carnivorous plants
All plants are harmless? Well, not quite - at least not when you're an insect...

Brood parasitism in cuckoos and other birds
Obligate brood parasitism has evolved several times independently in birds. Apart from the cuckoos, it can be found in four other, only distantly related families.

Monochromacy in mammals
Underwater environments are dominated by blue light. Ironically, whales and seals cannot see blue, because they have independently lost their short-wavelength opsins.

Foregut fermentation in birds
A foregut-fermenting bird was long considered a paradox. But what about the hoatzin, a curious South American bird known locally as the "stinking pheasant" thanks to its smell of fresh cow manure?

Foregut fermentation in mammals
Foregut fermentation is best known from the ruminants, such as cattle, deer and giraffes, that regurgitate and rechew their food to aid microbial digestion. However, they are not the only mammals to have evolved this digestive strategy...

Echolocation in bats
How can bats navigate in total darkness amongst trees and branches, but still locate a tiny, fluttering insect with extraordinary acuity? All made possible through echolocation, an astonishing sensory mechanism…

Electrolocation and electrocommunication in weakly electric fish
Fish have eyes, but they live in a much more complex sensory world, where even electricity plays a surprising - and convergent - role.

Snail eating: an asymmetric diet
Snails may not be everyone's first choice on the menu but several distinct colubrid snakes have evolved expert techniques for gorging on these nutritious gastropods.

Bioluminescence
Flying through the air on a summer's evening or sparkling in the ocean you may see magical flashes of light that signal some of nature's most enchanting creatures, those that are bioluminescent.

Light producing chemicals: how to make bioluminescence
The most remarkable luciferin in terms of its distribution is known as coelenterazine. This nitrogen-ring based molecule is found in nine separate groups, ranging from radiolarians to fish.

Why emit light? The many functions of bioluminescence
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Why emit light? The many functions of bioluminescence
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Light producing chemicals: how to make bioluminescence
The most remarkable luciferin in terms of its distribution is known as coelenterazine. This nitrogen-ring based molecule is found in nine separate groups, ranging from radiolarians to fish.

Bioluminescence
Flying through the air on a summer's evening or sparkling in the ocean you may see magical flashes of light that signal some of nature's most enchanting creatures, those that are bioluminescent.

Snail eating: an asymmetric diet
Snails may not be everyone's first choice on the menu but several distinct colubrid snakes have evolved expert techniques for gorging on these nutritious gastropods.

Vibrational communication in mammals
Kangaroo rats drum their foot on the ground upon encountering a snake. Why? Read on for this and many other fascinating examples of vibrational communication in mammals…

Vibrational communication in insects and spiders
Some spiders have evolved a most remarkable method of capturing other spiders – they imitate the vibrations of insects caught in their victim’s web. And this is only one of numerous intriguing examples of vibrational communication in arthropods…

Electrolocation and electrocommunication in weakly electric fish
Fish have eyes, but they live in a much more complex sensory world, where even electricity plays a surprising - and convergent - role.

Echolocation in bats
How can bats navigate in total darkness amongst trees and branches, but still locate a tiny, fluttering insect with extraordinary acuity? All made possible through echolocation, an astonishing sensory mechanism…

Foregut fermentation in mammals
Foregut fermentation is best known from the ruminants, such as cattle, deer and giraffes, that regurgitate and rechew their food to aid microbial digestion. However, they are not the only mammals to have evolved this digestive strategy...

Foregut fermentation in birds
A foregut-fermenting bird was long considered a paradox. But what about the hoatzin, a curious South American bird known locally as the "stinking pheasant" thanks to its smell of fresh cow manure?

Monochromacy in mammals
Underwater environments are dominated by blue light. Ironically, whales and seals cannot see blue, because they have independently lost their short-wavelength opsins.

Brood parasitism in cuckoos and other birds
Obligate brood parasitism has evolved several times independently in birds. Apart from the cuckoos, it can be found in four other, only distantly related families.

Carnivorous plants
All plants are harmless? Well, not quite - at least not when you're an insect...

Agriculture in marine polychaete annelids
Some polychaetes attach pieces of algae to their dwelling tube. Just for decoration? No, but for a much more substantial (and convergent) benefit...

Agriculture in wood wasps
The most famous hymenopteran farmers are, without doubt, the attine ants. Rightly so, but they are not the only ones...

Agriculture in dugongs
When you think of grazing mammals, you might envisage large herds of antelopes roaming African savannahs. Did you know that there is an equivalent in the ocean, feeding on seagrass?

Agriculture in gall midges (Diptera)
Flies, fungi, farming - sounds interesting? Read on if you want to learn about some rather different gall midges...

Agriculture in beetles
Think of weevils and most likely you'll think of spoiled food. But some weevils have turned to farming...

Agriculture in aquatic snails
Termites and ants are famous for tending fungal gardens, but did you know that also a marine snail farms a fungus? And this is not the only example of agriculture in this group…

Agriculture in damselfish
Don’t be tempted to think human agriculture is unique. On many coral rocks, there are very similar things going on…

Cichlids
Cichlids are one of the cause celebré of evolution, and rightly so because these freshwater fish show a remarkable diversity and exemplify many key aspects of adaptive radiation. But why so successful? The answer lies in the versatility of the jaws (and yes, they are convergent).

Vibrational communication in animals
What on earth could an elephant or treehoppers have in common with a seismometer?

Pressure sensitivity and the tactile sense (excluding the lateral line)
The star-nosed mole is famous for, well, its nose, but do you have any idea what these peculiar 'tentacles' are for? The answer is rather touching and, of course, convergent...

Secondary xylem (wood) in vascular plants
Evolution of wood in plants as distantly related as lignophytes, Calamites and Lepidodendron is an elegant example of convergent evolution. Plants responded in a similar way to a need for better structural support as they diversified and increased in size.

Torus-margo pits in vascular plant xylem
Torus-margo pits probably evolved once in the gymnosperms, after the split of more advanced gymnosperms from the cycads. Surprisingly, eight genera from five families of angiosperms, which are characterised by highly effective xylem vessels, have also evolved torus-margo structures.

Reversion from xylem vessels to tracheids
In three plant taxa that evolved in environments with frequent freeze-thaw cycles (Winteraceae, Trochodendraceae and cold desert Ephedra), vessel evolution has been reversed independently in favour of a return to a tracheid-based vascular system.

Xylem vessels in vascular plants
Vessels are characteristic of the angiosperms, and yet they have evolved independently in several other groups, including the lycophyte Selaginella, horse-tail Equisetum and the enigmatic Gnetales.

Malodorous flowering plants
Several groups of angiosperms have flower structures that produce foul odours to attract pollinating insects. This strategy is convergent, being found in species as distantly related as the 'Titan arum' Amorphophallus titanium (a monocot) and the 'Corpse flower' Rafflesia (a eudicot).

Foam nests in animals
Nests crop up everywhere, but one made out of foam? Might not sound like a great idea, but it is. And no surprise, it has evolved several times...

Lateral line system in fish and other animals
Some cavefish are completely blind, so how do they manage to navigate through their environment with astonishing ease?

Mitochondrial genome convergences
Most likely, mitochondria have a single evolutionary origin, but that doesn't mean they are immune to convergence...

Pufferfish (and inflation)
Pufferfish are some of the most extraordinary fish to have evolved, especially because of their capacity to swallow water and inflate themselves to something like a football. Not only that but some representatives can be deadly to the unwary diner...

Echolocation in birds: oilbirds and swiftlets
The best known example of echolocating birds are the South American oilbirds (Steatornis caripensis), so called because their flesh yields abundant oil.

Dicyemids and chromidinids: enigmatic endoparasites
Dicyemids and chromidinids are tiny, worm-like or 'vermiform' creatures that typically live inside the kidneys ('renal organs') of cephalopod molluscs such as octopus, squid and cuttlefish.

Evolution of birds from feathered reptiles
Birds, in the sense of flying descendants of feathered reptiles (a more expansive group than the "true" birds in today's skies), evolved several times from within the theropods.

“Broken jaw” – mandibular and maxillary jaw joints
At first sight having a jaw with a joint seems a contradiction in terms, but such exist and not only are obviously functional, but needless to say convergent.

Myelinated nerves in vertebrates, annelids and crustaceans
Myelinated nerves are an excellent biological solution and needless to say have evolved independently in several groups other than vertebrates. In each case myelination is associated with very rapid nervous conduction and often escape reactions.

Mimicry in fungi
Insects pollinating flowers are a familiar sight. But what happens when the "flower" is actually a fungus? Still "pollination", but now it is fungal spores. Read on to learn more about the fungi that mimic flowers...

Anointing in mammals
The strategy of anointing the body with the scent of a more dangerous animal has evolved independently several times, including in rodents, hegdehogs and tenrecs.

Explosive discharge in fungi and plants
The very rapid release of reproductive bodies is perhaps most famous in the fungi, where several methods of flinging spores at high velocity have evolved independently.

Moray eels
Eels masquerading as snakes sounds interesting, and that is before they go hunting with their friends the groupers...  

Collagen in animals and bacteria
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Autumn leaf colouration
Autumn colours are likely to be adaptive, as the 'default' is simply to remain green up to leaf fall, and both red and yellow leaf colouration have evolved independently on many occasions in gymnosperms and woody angiosperms.

Mushrooms and their relatives (Basidiomycota)
Mushrooms are not only tasty, but also provide numerous examples of evolutionary convergence...

Hummingbirds, sunbirds and honeyeaters
One of the most well known examples of convergence among birds is between hummingbirds, sunbirds and honeyeaters, all of which are small, dominantly nectar-feeding birds.

Suction feeding in fish, amphibians, reptiles and aquatic mammals
Probably everyone is familiar with the walrus, but did you know that it generates a vacuum in its mouth to suck clams out of their shells? And this is just one example of suction feeding, the feeding mode typically used by bony fish…

Tetrodotoxin
Not many foods served in a restaurant can kill you, but pufferfish is the exception. Tetrodotoxin, the toxin responsible for such culinary fatalities, reveals a fascinating story of convergent evolution...

Crustacean-trapping teeth in mesosaurs and crabeater seals
The multi-lobed post-canines of Lobodon carcinophagus are a functional analogue to the long, thin cage-like teeth of Mesosaurus, as both cage and prevent the escape of small crustacean prey.

Teeth in aquatic reptiles
Aquatic reptiles tend to display one of three dentition types, well adapted to either seize and slice large vertebrate prey, pierce and gouge slippery fish, or entrap small prey such as crustaceans.

Dental batteries in ceratopsians, hadrosaurs and elephants
The dental batteries or 'pavements' of ceratopsians and hadrosaurs evolved independently, and yet the dentition of several more distantly related animals also converges on their highly adapted tooth form.

Teiid lizard dentition: convergence with other reptiles, mammals and fish
Teiids are skink-like lizards whose members show a stunning diversity of tooth types, providing rich evidence of convergence within the teiids themselves, in distantly related reptile groups and even in certain mammals and fish.

Complex tooth occlusion in notosuchid crocodiles and tritylodonts (proto-mammals)
Two unusual Early Cretaceous crocodiles provide a shining example of convergence, as their dentition parallels that observed in a group of advanced proto-mammals called tritylodonts.

Reptile dentition: convergence on complex occlusion
Some reptiles have transverse chisel-like teeth for slicing, and others have teeth bearing projections ('cusps') that interlock and slice or grind tough food. In each case evolutionary parallels are clear both within and outside the reptiles.

Beak structures in reptiles and birds
Among reptile taxa with beak structures, we find several cases of convergent evolution, for example between turtles, Uromastyx lizards, a number of herbivorous dinosaurs and the tuatara (Sphenodon) of New Zealand.

Venom and venom fangs in snakes, lizards and synapsids
Although the evolution of snake fangs itself provides us with a window on convergence, the presence of fang-like teeth in lizards, therapsids and mammals provides an even broader and more remarkable perspective.

Desert plants with succulent stems
Fleshy, succulent stems have evolved in several distantly related desert plant families, including cacti, certain species of Euphorbia and two genera of the family Asclepiadaceae, Hoodia and Stapelia.

Desert plants with succulent leaves
Perhaps the most striking case of convergence among leaf succulents occurs between Agave and its relatives Yucca and Hesperaloe in the Americas and Aloe and its relatives (e.g. Haworthia and Gasteria) in Africa.

Succulent desert plants
Classic examples of convergence in desert plants include the so-called 'stem succulent' cacti in the Americas and cactus-like Euphorbia species in Africa and South Asia, and also the striking similarity between 'leaf succulent' Agave and Yucca of the Americas and Aloe and its close relatives in Africa.

Feeding in snakes and lizards
The Turtle-headed sea snake feeds on small eggs and its feeding shows intriguing similarities to the way lizards forage, and herbivorous mammals graze and browse.

Crabs: insights into convergence
You might think of crabs mainly as food, but this group is also highly instructive in terms of convergence…

Limblessness in lizards
What's that slithering towards you? A snake? Look more closely, look convergently...

Independent eye movement in fish, chameleons and frogmouths
One of the most surprising convergences amongst animals is that seen between a small fish that lives in coral sands, known as the sandlance, and the lizards known as chameleons.

Carnivorous fungi: a diet of worms (and other animals)
Fungi have learnt how to trap living prey, notably nematodes but also a range of other animals include rotifers, tardigrades and even springtails.

Ascomycete fungi: insights into convergence
Today ascomycetes are an extremely important group of fungi, and they take their name from the reproductive structures known as ascii.

Saxitoxin synthesis: from molluscs to algae
Saxitoxin has a similar molecular structure to tetrodoxin and a wide distribution amongst living organisms, with evidence that is has been recruited independently several times.

Bats: Insights into convergence
Bats show a fascinating array of convergences, from echolocation to flight to nectar feeding. Vampire bats can even detect infrared radiation, while others might be able to see into the ultraviolet end of the spectrum.

Echolocation in toothed whales and ground-dwelling mammals
Given the extraordinary powers of echolocation in bats, it is not surprising that this group has received the most attention. However, they are not the only mammals to have evolved echolocation. Who invented sonar millions of years before the Navy?

Thanatosis (feigning death) in spiders and insects
Beetles that "play possum"? A rather interesting example of convergence…

Nuptial gifts in insects and spiders
Male dance flies lure females with a dead insect. Not very romantic, you might think, but it certainly does the trick. Hence, such nuptial gifts have evolved in numerous other arthropods...

Dandruff, Malassezia and Candida
The presence of Malassezia does not guarantee dandruff, as this fungus is commonly present on healthy skin, but it evidently central to dandruff production if other key factors support it.

Camera eyes in cubozoan jellyfish
On each of the four club-like extensions (rhopalia) near the base of the cubozoan jellyfish bell there are two camera-eyes, one pointing upwards and the other downwards.

Pharyngeal jaws in teleost fish
One of the great evolutionary breakthroughs in the teleost fish was the conversion of some of the elements that supported the gill bars into a second set of pharyngeal teeth that complemented the oral teeth. See how a fish becomes a snake!

Durophagy (hard prey-eating) in fish
Plenty of animals have an extraordinary capacity to crush hard prey and this has evolved independently many times in the vertebrates. If you suspect it is a durophage, watch your fingers!

Magnetotactic bacteria
Magnetotactic bacteria provide some excellent examples of convergent evolution.  In particular the ability to synthesize iron compounds has evolved at least twice, respectively employing iron oxide (magnetite) and iron sulphide.

Ink production in cephalopods and gastropods
A series of striking convergences can be found in the sea-hares (Aplysia), a group of gastropods and only remotely related to the cephalopods.  Not only do they emit ink clouds (the colour is derived from ingested red algae), but they also employ chemical cues that assist in defense.

Dinoflagellate “nematocysts”
Examples of convergence within the dinoflagellates range from the evolution of a camera-like eye to stinging 'nematocysts' reminiscent of those in jellyfish.

Extremophiles: Archaea and Bacteria
Surely, no organism can survive in boiling water or brines nine times the salinity of seawater? Wrong - some archaea and bacteria have independently evolved adaptations to such extreme environments...

Gliding lizards, frogs and ants
Tree-dwelling (‘arboreal’) ants capable of controlled gliding do so when dislodged or threatened by predation. Gliding species include members of three disparate families: Myrmicinae, Pseudomyrmecinae and Formicinae.

Gliding in feathered reptiles
A number of reptile species have been discovered in the Mesozoic fossil record, bearing feathers that were apparently used to support gliding locomotion, rather than true, powered flight as we see in present day birds.

Gliding in Draco lizards and tree snakes
“The agamid lizard genus Draco (consisting of the so-called ‘flying dragons’) exhibits an array of morphological traits associated with gliding.” – A.P. Russell & L.D. Dijkstra (2001) Journal of the Zoological Society of London, vol. 253, page 457

Gliding mammals
Gliding mammals rely primarily on extensive skin membranes or ‘patagia’ that stretch between fore- and hind-limbs, creating a wing-like structure.

Gliding reptiles
In the reptiles, different forms of skin membrane (called ‘patagia’) and in some extinct species, primitive feathers, have evolved convergently as adaptations for gliding.

Sand-dwelling (psammophilous) lizard ecomorphs
Desert sand dunes represent an extreme environmental setting in which selective forces have apparently generated dune ‘ecomorphs’ in six lizard families. – Lamb et al. (2003) Biological Journal of the Linnean Society, vol. 73, p. 253

Ecological adaptations in Moloch and Phrynosoma lizards
Lizards of the genera Phrynosoma and Moloch have been considered a classic example of convergent evolution J. J. Meyers & A. Herrel (2005) The Journal of Experimental Biology, vol. 208, p. 114

Drinking adaptations in desert lizards
Both Moloch horridus and [...] Phrynosoma cornutum have the remarkable ability to transport water over their skin’s surface to the mouth where drinking occurs. Sherbrooke et al. (2007) Zoomorphology, vol. 126, p. 89

Parthenogenesis in Australian lizards and insects
“Evidence on the origin and spread of the two best-studied cases of parthenogenesis from the Australian arid zone, the grasshopper Warramaba virgo and the gecko Heteronotia binoei, suggests that they evolved in parallel.” – Kearney et al. (2006) Molecular Ecology vol. 15, p.1743

Anolis lizard ecomorphs
“A classic example of convergent evolution is the set of Anolis lizard ecomorphs of the Greater Antilles.” – Langerhans, Knouft & Losos (2006) Evolution, vol. 6, p.362

Mammal-like placentation in skinks (and fish)
“Only two types of vertebrates [have] evolved a reproductive pattern in which the chorioallantoic placenta provides the nutrients for fetal development. One is [...] the eutherian mammals […], and the other, a few lineages of the family Scincidae.” A.F. Flemming (2003) J Exp Zool 299A 33-47

Viviparity in sauropterygians
“The [fossilised] embryos are mostly in articulation and their distribution on each side indicates that female Keichousaurus hui had a pair of oviducts as in ichthyosaurs and many extant lizards.” Y. Cheng et al. (2003) Nature vol. 432, p.383

Viviparity in mosasaurs
An exceptionally preserved gravid female of the aigalosaur Carsosaurus contains at least at least four advanced embryos […] Their orientation suggests that they were born tail-first […] to reduce the possibility of drowning, an adaptation shared with other other highly aquatic amniotes” M.W. Caldwell & M.S.Y. Lee (2001) Proceedings of the Royal Society of London B, vol. 268, p.2397

Viviparity in ichthyosaurs
“For me, the fossil is a transporting piece of evidence. It shows a female ichthyosaur that died late in pregnancy or perhaps while giving birth; the baby was entombed with its mother in the mud.” J. Rennie (2000) Scientific American, vol. 283(6), p.8

Viviparity in lizards, snakes and mammals
“In over 100 lineages of […] squamates, the oviduct has been recruited for viviparous gestation of the embryos, representing a degree of evolutionary convergence that is unparalleled in vertebrate history.” D. G. Blackburn (1998) Journal of Experimental Zoology, vol.282, p.560

Trichromatic vision in mammals
Who has not enjoyed the splash of colour in a market: gorgeous red peppers, the green of basil and what on earth are these purple vegetables over there? All thanks to trichromatic vision, another story of convergence.

Olfaction: insights into convergence
Although olfaction is very widespread, there is abundant evidence for repeated convergence of key features, strongly suggesting that there really is an optimal solution to detecting smells.

Venom in mammals (and other synapsids)
Beware the venomous shrew! Yes, venomous. And convergent on some formidable lizards...

Infrared detection in insects
Whilst infrared detection is probably best known in the snakes (where it has evolved twice), in point of fact in terms of convergence the insects provide by far the most striking example.

Infrared detection in snakes
Warm-blooded rodents watch out! There are heat-sensing predators on the prowl...

Infrared detection in animals
Some snakes are famous for 'seeing' infrared, but did you know that their heat-sensing abilities are rivalled by some beetles that can detect forest fires over considerable distances?

Taste in arthropods and mammals
The ability to taste is obviously an essential component in the life of any animal, both to assess the potential quality of food, its nutrient capacities and also to detect toxins or other dangers.

Loss of olfactory capacity in primates and cetaceans
It is widely thought that reduced olfactory capacity in apes is linked to the development of acute vision, especially trichromacy.

Ancient opsins and vision in extinct animals
Spectral tuning of the eye generally depends on key substitutions of amino acid sites in opsin proteins.

Mitochondrial lens formation in flatworms
In some of the flatworms (platyhelminthes) the lens is formed from mitochondria, and it is intriguing to speculate whether a mitochondrial enzyme has been co-opted to provide a crystallin.

Hearts in cephalopods and vertebrates
There is a striking convergence between the aorta of the cephalopod and vertebrate heart, notably in its structure and the employment of elastic proteins.

Corneal nipple arrays in insect eyes
Anti-reflection coating? Not only on mobile phone displays, but also on insect eyes...

Vision in echinoderms
Among brittlestars and sea urchins we find visual systems that in some ways rival the arthropods in the form of compound eye-like structures.

Lipocalins for milk and pheromone transport
Lipocalins are proteins that bind to and transport small hydrophobic molecules such as lipids and steroids, and have been associated with biological processes such as milk production, pheromone transport and immune responses.

Wire plants, moas and elephant birds
Madagascar and New Zealand were once home to giant herbivorous birds. And the plants have not forgotten...    

Compound eyes in arthropods
It is clear that amongst the arthropods as a whole the compound eye has evolved at least twice, and possibly even more times.

Compound eyes in sabellid annelids
Compound eyes have evolved convergently in the annelids, notably amongst the sabellids, where they evidently serve as an optical alarm system.

Camera eyes in alciopid annelids
There is a striking example in the group known as the alciopids, which are pelagic polychaetes. The similarity of their camera eye to the vertebrate eye has attracted considerable comment.

Pinhole eyes in Nautilus and giant clam
The pinhole eye has evolved not only in the Pearly Nautilus, but also in another group of molluscs, the bivalves and specifically the giant clams (Tridacna).

Compound eyes in ark clams
Read on if you want to know more about bivalves with burglar alarms…

Camera eyes in gastropod molluscs
The fast-moving cephalopod molluscs are famous for their camera eyes, but why on earth have gastropod snails, which are not exactly known for their speed, evolved this superb visual organ at least four times?

Scanning eyes in molluscs and arthropods
Some sea snails have a linear retina. What a hopeless arrangement, to see the world through just a narrow slit! Not quite, because they have come up with a rather intriguing trick to extend their visual field - and it's a trick too good to use only once.

Telephoto eyes in animals
Pursued by the paparazzi? Watch out for those animals equipped with telephoto lenses...

Camera-like eyes in arthropods
Arthropods are famous for their compound eyes, but some groups have had a fair crack at evolving the optically superior camera eye…

Innate and adaptive immune systems
A vile cough, soaring temperature? When attacked by nasty microbes, our immune system comes in handy. Surprisingly (or not), plants have come up with a very similar solution to dealing with pathogens, but independently...    

Adhesive pads: from geckos to spiders
In terms of adhesive pads we find they have a remarkably wide distribution evolving in at least four distinct groups, including members of the reptiles, amphibians, arthropods and mammals, with tentative parallels in sea urchins.

Silk production and use in arthropods
Remarkably, fossil silk is known, especially from amber of Cretaceous age. Material includes both silk with trapped insects, possibly from an orb-web, and strands with the characteristic viscid droplets that are the key in trapping prey.

Mussel attachment and the Pinna byssus
It is clear that the Pinna byssus has unusual properties in comparison to its equivalent in the bivalve mussel, and is conspicuously different in terms of crystallinity.

Spitting in spiders and velvet worms
Scytodid spiders forcibly eject a mixture of saliva, silk and venom in a glutinous mass over a distance of c. 1cm to entrap prey.

Biological uses of silk: from webs to ballooning
What material is so versatile that it can be used for capturing prey, building nests, communication and even cleaning? The answer: that most remarkable of biomaterials - silk.

Bacterial carboxysomes (and other microcompartments)
It is now clear that the cellular construction of at least the eubacteria is more complex than realized, and includes organelle-like structures known as microcompartments, of which the best known are the carboxysomes.

Lysozyme
Lysozymes are common antibacterial enzymes that protect our eyes and nose from infection, but some animals have recruited them for a rather different purpose...

Enzymes: convergence on active sites and reaction types
Enzymes make the world go round, each an evolutionary marvel - and convergent.

Intelligence and cognition in birds
House sparrows are known to gain access to shopping malls by flying in front of sensors that operate sliding doors, whilst herons have been shown to be adept fishers using baits and lures.

Birds: insights into convergence
Intriguing ecological and morphological parallels can be found among the Neoaves. Many of these forms were initially believed to be each other's closest relatives, but are now widely recognised as classic examples of convergence. Think how similar swifts and swallows are, but they are only distantly related.

Gut fermentation in herbivorous animals
Ever tried eating a newspaper? Don't. Plant cell walls contain cellulose, which is notoriously difficult to digest. Considering that all vertebrates lack the enzymes to attack this polysaccharide, how do so many of them manage to survive on a plant diet?

Carbonic anhydrase in vertebrates, plants, algae and bacteria
Carbonic anhydrase is extremely convergent and may have evolved as many as six times. The most familiar variants are α, β and γ carbonic anhydrases.

Baculum (penile bone) in mammals
Ouch!! Gentlemen, fancy a bone in your penis? Seems a bit risky, given it could fracture during copulation. Even our near ancestors had such a bone. It has probably evolved several times, but what is its function?

Tool use in birds
What animals can drop stones into a water-filled tube to bring floating food within reach or bend wire to form a hook? Obviously chimpanzees? No, New Caledonian crows have evolved sophisticated tool use too.

Sabre-toothed cats and marsupials
Marsupials with giant fangs? Yes, not all of the extinct sabre-toothed cats were actually cats…

Sap feeding and honey-dew production in insects
Interestingly, it has now been shown that the saliva of the aphids has an analogue to the anti-coagulant properties of blood suckers, subverting the wound repair mechanism of the plant.

Cavitation: bubble formation in plants, reptiles and shrimps
The formation of bubbles in a fluid is known as cavitation. Typically this occurs at low pressures, and is perhaps best known in the xylem of plants where embolisms can be destructive to the surrounding tissues.

Electric fish: insights into convergence
Ever seen an electric eel in an aquarium? Don’t dare putting your hand in the tank...

Dolphin communication, cognition and sociality
Dolphins are one of the most intriguing sources of evolutionary convergence, having cognitive abilities that seem to find many parallels in the great apes, and rather remarkably even extend to tool use.

Chloroplast and mitochondrial plastid origins
Not only are there intriguing parallels in the story of gene loss in chloroplasts and mitochondria, but there is also the re-invention of bacterial pathways, such as oxidation of quinols.

Strepsipterans: convergent halteres and eyes
Strepsipteran females spend their whole life inside a wasp. The males are rather more exciting, particularly in terms of convergence…

Sleep in animals
Suffering from insomnia? Fruit flies do as well...

Agriculture: from ants to dugongs
Human farmers tending their fields are a familiar sight. But don't forget about those fungus-farming termites or the fish with a garden of algae…

Zinc in teeth
On land, we find the employment of zinc to reinforce feeding structures in the fangs of spiders, and also in a variety of insect groups.

Beetles: insights into convergence
The beetles are probably the most diverse animal group on earth, so it is not at all surprising that they provide many fascinating insights into convergence.

Agriculture in ants: leaf-cutters (attines) and non-attines
In some species, special squads leave the nest early each day, ascend the tree-trunks and then spend hours cutting out pieces of leaf that are dropped to other units on the ground.

Woodpeckers and woodpecker-like birds and mammals
You think woodpeckers are unique? Consider the ovenbirds. Or even the curious aye-aye.

Hummingbirds and hummingbirdoid moths
Like other birds hummingbirds are warm-blooded, but so independently are the hawk-moths, which like a number of insects have evolved thermoregulation.

Swimming and thermoregulation in sharks and tuna
Thunniform swimming depends on a large, lunate tail that is joined to the rest of the body via a narrow peduncle. Whilst the tail flicks backwards and forwards, so propelling the animal, the rest of the body hardly moves sideways.

Ecology and cosmetics in vultures
Vultures are not only charistmatic birds in the popular imagination, but are strikingly convergent, especially regarding feeding types...

Developmental genetic pathways to convergence
At first sight there is a fairly simple dichotomy between convergent features that have effectively the same genetic basis, and those where the same feature emerges but the underlying genetics are different. The former, however, is somewhat more complicated...

Ants: insights into convergence
Trap-jaws, silk and agriculture – just a few examples of convergence in the arguably most successful group of insects, the ants…

Crustaceans: insights into convergence
Whilst predominantly marine, quite a number of crustaceans have invaded freshwater habitats and even more interestingly a few demonstrate terrestrialization, effectively freeing themselves from their aquatic ancestry.

Haemocyanin in arthropods and molluscs
The degree of similarity between the active sites in arthropod and molluscan haemocyanin has been called “remarkable” and “startling”, but actually suggests that wherever in the universe life employs copper for aerobic respiration it will call upon haemocyanin.

Elastic proteins
What do rubber bands and fleas have in common?

Crystallins: eye lens proteins
Whereas typically technology demands furnaces, so that the glass for a lens is produced at hundreds of degrees Celsius and then requires most careful grinding, so nature calls upon proteins known as crystallins.

Transparent tissues: eyes, bodies and reflective surfaces
Read on if you want to know about the numerous animal equivalents to the invisible man...

“Colour vision” in Firefly squid
The Japanese firefly squid (Watasenia scintillans), which inhabits the deep ocean, has three visual pigments located in different parts of the retina that are likely to allow colour discrimination as they each have distinct spectral sensitivities.

Love darts in slugs, snails and annelid worms
The curious habit of stabbing their partners with sharp calcareous (or chitinous) darts during courtship and prior to actual copulation has understandably attracted considerable attention.

Penis form in mammals, turtles, birds and octopus
The specific case of a penis with a hydrostatic structure, as well as an array of collagen fibres that allows both expansion and guards against aneurysms, has evolved in a strikingly convergent fashion in mammals and turtles.

Simple tool use in owls and cephalopods
Burrowing owls place pieces of collected dung. These attract insects such as beetles that are then eaten by the owls.

Worm-like body form
Man is but a worm, but so are many other vertebrates...

Tongues of chameleons and amphibians
[p]Convergence in tongue function represents repeated morphological exploration within different lineages made possible by loss of an ancestral functional constraint[/p]

Frogs with fangs
Teeth have clearly evolved a number of times, and one of the more interesting curiosities is found in the amphibians, notably in the frogs where several groups have independently evolved fangs.

Electroreception in fish, amphibians and monotremes
From an evolutionary point of view, electroreception is particularly intriguing as a sense modality that has been repeatedly lost and reinvented again.

Burrowing: from worms to vertebrates
Quite a few adaptations are useful for burrowing into the soil. So it is not exactly surprising that they have evolved several times...

Defence in frogs: toxins and camouflage
The many striking examples of convergence most famously include the case of mimicry, but the question of defence also extends to the use of toxins (and venoms), such as alkaloids, where we also find molecular convergence.

Octopus arm function
If you want to see a truly remarkable example of convergence, then present an octopus with a piece of food and have a high-speed camera ready…

Camera eyes of cephalopods
The remarkable similarity between the camera eyes of cephalopods and vertebrates is one of the best-known examples of evolutionary convergence.

Octopus and other cephalopods: convergence with vertebrates
What could be more different from us than the alien-like octopus? Hold on. Look it in the eye and think again.

Camera eyes in vertebrates, cephalopods and other animals
Camera eyes are superb optical devices, so it is not surprising that they have evolved several times. But why, of all animals, in the brainless jellyfish? Or for that matter in a slow-moving snail?