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.

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.

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…

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.

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.

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.

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…

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).

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?

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...

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.

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...

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.

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

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!

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.

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 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.

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

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.

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…

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.

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...

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…

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.

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.

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.

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.

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?