Most animals and plants are part of more than one food chain. If one part of a food chain alters, the whole food chain is affected. For example, if a disease suddenly wiped out caterpillars, it would affect mice, owls and many other animals.
This phylum consists of the jellyfish, hydra, sea anemones, corals, sea pens, sea wasps, and box jellyfish. There are about 9,000 species. Almost all are marine. This is another ancient group, with fossils perhaps reaching back to 700 mya.
Marine herbivores are found within four groups of species in the animal kingdom -- invertebrates, fish, reptiles and mammals -- and include zooplankton, mollusks, the green sea turtle, the marine iguana and some fish species.Manatees and dugongs are the only herbivores among marine mammals.he majority are carnivores and omnivores, but a relatively small number are herbivores, such as some sea snails -- the black-footed paua, top shell snails, limpets, turban shells, abalones and conch -- sea hares and sea cucumbers who graze on algae, seaweed and other plants.