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

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…

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

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.

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.

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.

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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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.

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.

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

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.

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).

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.

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...

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.

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.

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.

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.

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.

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?

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.

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!

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.

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.

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

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.

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...

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.

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.

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.

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).

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…

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.

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?

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.

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

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...

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.

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.

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?

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.

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?