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.
Somehow they've resisted becoming crabs
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!