The forelimb of cetaceans (whales, dolphins, and porpoises) has been radically modified during the limb-to-flipper transition. Extant cetaceans have a soft tissue flipper encasing the manus and acting as a hydrofoil to generate lift.

Why do whales have forelimbs?

The forelimbs of chimpanzees are adapted for climbing trees, those of whales to support flippers for moving through water, and those of bats to support membranous wings for flying.

What are whale arms called?

Whales generally have four fins: two pectoral fins (instead of arms), a caudal fin (also called the tail) and a dorsal fin. The caudal fin is used for propulsion of the animal, with up-and-down movements created by powerful muscles along the peduncle. The two pectoral fins serve as the whales' rudders and stabilizers.