Fish, in families. Fish, in schools.
These are all ray-finned fishes, on a chart showing how they became more diverse from the Devonian period (when oceans were the “in” places for life forms to hang out) to the Triassic (when dinosaurs started making the scene).
Ray-finned fish are one of two groups of bony fish (which is the big group of, basically, all the fish that aren’t sharks, rays, hagfish or lampreys). The other group of bony fish are lobe-finned fish, which are fish like coelacanths – the ones that got a little leggy and started putting on airs.
Ray-finned fish are fish as you think of fish, most likely. Snapper, bass, anglerfish, sturgeons, goldfish, and sea robins… all in the family. Or, uh, clade. You know what I mean.
[via Scientific Illustration]