Ctenophora predation by ctenophores may control the populations of small zooplanktonic organisms such as copepods, which might otherwise wipe out the phytoplankton (planktonic plants), which are a vital part of marine food chains. Almost all ctenophores are predators – there are no vegetarians and only one genus that is partly parasitic. If food is plentiful, they can eat 10 times their own weight per day. While "Beroe" preys mainly on other ctenophores, other surface-water species prey on zooplankton (planktonic animals) ranging in size from the microscopic, including mollusc and fish larvae, to small adult crustaceans such as copepods, amphipods, and even
Marine mammals as food blubber is used to make seal oil, which is marketed as a fish oil supplement. In 2001, two percent of Canada's raw seal oil was processed and sold in Canadian health stores. There has been virtually no market for seal organs since 1998. Archaeological evidence indicates that for thousands of years, indigenous peoples have also hunted sea otters for food and fur. Marine mammals as food Marine mammals are a food source in many countries around the world. Historically, they were hunted by coastal people, and in the case of aboriginal whaling, still are. This sort of subsistence hunting was