Recall that angiosperms protect their embryos in seeds like gymnosperms, but then furthermore pack their seeds with endosperm and protect them inside fruit. Flowers serve to attract pollinators. Some Cnidarians exhibit both or only one of these two forms during their life cycles, e.g. sea anemones exist only as polyps, and jellyfish exist only as medusas, whereas most hydras alternate between both polyp and medusa forms. Animals are multicellular heterotrophic eukaryotes that ingest their food to acquire essential nutrients that they cannot assemble de novo . Animals lack cell walls.
Reproduction is primarily sexual.
Many animals undergo development from a larval form to an adult form, where the two forms may be quite distinct in morphology and ecology.