Mammals keep turning weasel shaped. Mustelification (a term I made up) is the tendency for a fuckton of unrelated mammals to have long thin bodies with stout, powerful legs.
There's no such thing as a "fish". There's loads of animals in the ocean that are utterly unrelated, but both have scales and fins because fish is a useful shape in the ocean.
There are several major classes of "fish". Sharks belong to the cartilaginous class (along with rays and skates). The other major classes are the lobe-fins and the ray-fins. The ray-fin class consists of most of the typical fishy fish that we are familiar with, like salmon, goldfish and tuna. The lobe-fins consist of lungfish and ALL TETRAPODS! That's right, you and I are technically lobe-finned fish.
Also, tuna are more closely related to humans than they are to sharks.
Crustaceans keep turning crab shaped.
Mammals keep turning weasel shaped. Mustelification (a term I made up) is the tendency for a fuckton of unrelated mammals to have long thin bodies with stout, powerful legs.
There's no such thing as a "fish". There's loads of animals in the ocean that are utterly unrelated, but both have scales and fins because fish is a useful shape in the ocean.
There are several major classes of "fish". Sharks belong to the cartilaginous class (along with rays and skates). The other major classes are the lobe-fins and the ray-fins. The ray-fin class consists of most of the typical fishy fish that we are familiar with, like salmon, goldfish and tuna. The lobe-fins consist of lungfish and ALL TETRAPODS! That's right, you and I are technically lobe-finned fish.
Also, tuna are more closely related to humans than they are to sharks.
Dolphins are lobe-finned fish.
Just thinking about that longass evolutionary journey they took to end up right back to looking like a shark is exhausting!