There are 19 species of penguins. The primary predators for most penguins in Antarctica are the leopard seals. Large whales have also eaten penguins. On land, adult penguins do not tend to have predators, although dogs (when brought by man) have eaten many. However, penguin eggs and chicks in Antarctica have the skua birds as predators.

I hope this helps. I really can’t answer your question regarding plankton. You may want to try an encyclopedia for that one.

Good luck! Jim P.