Sponges are aquatic animals. However, they resemble plants more than animals. More than 5,000 different kinds of sponges exist across the world. They can be green, brown, yellow, red, orange, white, etc. Sponges have various shapes such as fan, dome, vase, bowl or trumpet shaped. A sponge has no sense organs so it does not react on touch. It also does not have a heart, stomach, nervous system or muscles. Sponges feed on small plants and animals present in water.
What is a Sponge?
