Hobbies And Interests
Simple Life
Many ocean floors, reefs and so on are comprised of sessile or semi-sessile life such as bivalves, sponges and corals. Some mobile animals, such as jellyfish, begin their lives on the seabed as sessile polyps and later become mobile. The current theory of evolution purports that these types of animals are the ancestors of the vast majority of subsequent animal lifeforms.
Crustaceans and Bottom Dwellers
Crustaceans are an extremely ancient form of life, thought to be at least 250 million years old. Most are marine organisms and range from very tiny, free swimming planktonic animals to very large crustaceans like the horseshoe crab, the American lobster and the coconut crab, which dwell on sea beds. Many flat fish such as the flounder and sole have specifically evolved to feed on the ocean floor. Cephalopods such as squid and octopi lurk in seabed grottoes to capture prey.
Fish
A fish is characterized by gills and lack of digits on its limbs, meaning this includes eels and cartilaginous fish (i.e. sharks). This is a huge category of animal, ranging from very social creatures like mackerels, who travel in schools of many thousands to predatory fish such as sea bass, tuna, salmon and sharks.
Mammals
The most prominent sea mammals are porpoises, dolphins and whales, who have blowholes, surface for air and give live birth. Whales are the largest organisms on the planet and the blue whale in particular is the largest animal known to have ever existed. Dolphins are especially well regarded because they are among the most intelligent animals on Earth, comparable with chimpanzees.