Aquatic Ecology Course Zoo 374

Prof.Dr.Hanan M Mitwally, Marine Biology B=Marine Mammals Otters Polar bear Dolphin

Prof.Dr.Hanan M Mitwally, Marine Biology Sea lionswalrus Seals Manatees

Dugongs, or sea cows as they are sometimes called, are marine animals which can grow to about three metres in length and weigh as much as 400 kilograms. They are the only marine mammals in Australia that live mainly on plants. The name sea cow refers to the fact that they graze on the seagrasses, which form meadows in sheltered coastal waters. As dugongs feed, whole plants are uprooted and a telltale-feeding trail is left. Dugongs are more closely related to elephants than to marine mammals such as whales and dolphins, but manatees are their closest living aquatic relatives.

Oceanic birds spend most of their lives in or on the water and derive their sustenance

The Albatross is almost as much a marine animal as a whale. They spend months wandering great distances over the oceans. They sleep while floating on the ocean surface, drink seawater, and feed on cuttlefish, other small marine animals. They return to land only to breed Well-known species include the wandering albatross, a huge bird with a 3.4 m (11 ft) wingspread. Albatrosses nest on barren islands, close to shore; usually the nest is a depression in the ground containing a single egg.

* Penguins are true marine animals * They only come on shore to breed, return to the same breeding grounds every year * The rest of the time they are in the water or on the ice

* The diet of the Penguins is unremarkable; it consists of small shoaling animals, small fish and various crustaceans * These animals, in turn, feed on zooplankton, which feed on phytoplankton

As mentioned before, Most nekton are chordates, animals with bones or cartilage. This category of nekton includes: * Bony fish (most common) * Cartilaginous fish (sharks and rays) * Mammals (whales, seals, porpoises and dolphins) * Reptiles (Turtles, snakes, iguana and saltwater crocodiles) * Sea birds (Penguins) Others are molluscan nekton like cephalopods, as squid, clams and octopus which are invertebrates, animals with no bones. However, molluscan nekton have no outer shells.