Sponges belong to the kingdom Animalia and phylum Porifera. Although commonly mistaken for plants, they are actually living creatures found in oceans, seas and rivers around the world.
There are three classes of sponge, Calcarea, Demospongiae and Hexactinellida. Sponges are multicellular and come in a wide variety of colors. The creatures do not move but remain fixed to the bottom of the sea or river in which they grow. They filter food from the water as it moves throughout the cells in their body. Many sponges are hermaphroditic. Some reproduce asexually, while others reproduce when male sponges release sperm that is pulled into the female sponge's eggs from the surrounding water.