Module · 1

Independent origins, organized by trait.

Pick a trait. The lineages that arrived at it — separately, without inheriting it — are listed below. The MYA tag marks roughly when, in millions of years ago.

Vertebrates

~530 MYA

Vertebrata

env

Open marine, then everywhere

note

Inverted retina; blind spot.

Cephalopod molluscs (octopus, squid)

~480 MYA

Cephalopoda

env

Marine, mid-water predators

note

Non-inverted retina; no blind spot. The same problem solved more cleanly.

Box jellyfish

~500 MYA

Cubozoa

env

Tropical shallows

note

24 eyes total. Some image-forming despite no central brain.

Spiders (some)

~150 MYA

Salticidae and others

env

Diurnal hunters

note

Jumping spider eyes form a true focused image with retinal scanning.

Annelid worms (Nereididae)

~400 MYA

Polychaeta

env

Marine sediments

note

Independently evolved a small but image-forming chambered eye.