Bony fish and their descendants

You belong in this bony family, in a family-tree way. This group holds every fish with a skeleton made at least partly of true bone, from goldfish to tuna — and it also holds you. Its closest cousins outside the group are sharks and rays, whose skeletons are made of cartilage instead of bone.

A typical fish in this group has a streamlined, torpedo-shaped body with two eyes, jaws, and gills tucked under a hard bony flap on each side. Most of these fishes wear overlapping flat scales, often silvery, blue-grey, green or brown, usually with fins on the sides, on top, below and at the tail. Inside the group are two big branches: ray-finned fishes, with thin skin fins held up by bony rays, and lobe-finned fishes, with thick, fleshy fins with bone and muscle inside.

The lobe-finned branch also gave rise to a four-limbed family, from frogs to birds to people, who share the same bony body plan with limbs instead of fins. With them, this family swims in almost every sea, river and lake, and lives on land almost everywhere.