Simple animals include species like sponges and jellyfish. According to EarthLife.net (see cite page) sponge is "...a sedentary, filter feeding metazon." The sponge itself is multicellular but it has few tissues and live attached to something else. By absorbing water, sponges filter the water getting nutrients from things in the water then ejecting it. Jellyfish are animals made up by a jelly like substance. Some eat by stinging their prey and injecting toxins.

Simple Animals