No.
Bset science can tell mammals were first land living. And the creatures that eventually became whales for some reason opted for a more aquatic Lifestyle.
Sea mammals
Dolphins, Killer whales and Whales are all sea mammals Plus dolphins eat crab. Killer whales eat either fish or seal meat.
Most of these are mammals MOST of these are mammals. MOST of these are mammals.
Dolphins are sea creatures but they are also mammals like whales.
The big whales as a rule don't eat marine mammals, but Orcas - killer whales - will eat seals, sea lions, and even other whales when they have the chance.
Antarctica is a continent: whales are sea mammals. And yes, you can find whales in the water surrounding Antarctica.
Nouns are people, places, and things. The nouns in your sentence are "whales," "fish," and "plankton."
There are four main groups of marine mammals. They are cetaceans which include whales and dolphins, pinnipeds which includes seals and sea lions, sirenians which are manatees and dugongs, and fissipeds which are polar bears and two species of otters.
Besides other mammals, killer whales feed on birds, sea turtles, penguins, reptiles, sharks and octopuses.
They are called marine mammals, more specifically cetaceans (whales, dolphins) rather than manatees or dugongs, or semi-aquatic mammals such as seals, sea lions, and otters.
Dolphins,whales,guppy and lots more
Dolphins and whales are mammals, as well as manatees and otters.