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?

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.

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

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.

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.

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.

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.

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

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.

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).

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…

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…

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.

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

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?