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.
Bite-Sized Biology Learning. The phylum Porifera contains the simplest creatures of the animal kingdom. Sponges are aquatic sessile organisms (they are unable to move by themselves and they remain attached to substrates). They do not have tissue diversity and their bodies have pores (the feature form which their name is derived).