Te bottom of the food chain would be phtoplankton which are really tiny organisms which are eaten by small fish to whales. Small fish are fed upon by bigger fish etc.
السماك
It is a natural instinct like eating and drinking...
It depends on the options of the animals you are talking about sorry!
In the ocean.
animals,plants that live in the ocean
animals usual find food by smelling it or they will kill an animal for food
sharks,fish,algae
Antarctica is a continent and the animals you name are sea animals. They eat their food from the food chain in the Southern Ocean.
In the open ocean you can find the Blue whale
The ocean
in the ocean
from the ocean