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.
The sea is home to billions of plants and animals. Many live only near the sunlit surface. Here you'll find everything from microscopic plankton to the giant blue whale. Oceanographers classify marine organisms by separating them into two primary groups: plants and animals.hese are usually single-celled, minute floating plants that drift throughout the surface waters of the ocean. A bucket of sea water might hold a million microscopic diatoms which are relatives of seaweed encased in glassy boxes. To grow, phytoplankton need nutrients from the sea water and lots of sunlight.