Four different species of sponges grow near each other on this reef in the Caribbean Sea. By Twilight Zone Expedition Team 2007, courtesy of NOAA.
If you saw a sponge, you might think that it was an underwater plant. Sponges are really animals with very simple bodies, but their movements are so small that it is almost impossible for humans to see them move.
Sponges live on the ocean floor. They attach themselves to hard surfaces and wait for ocean currents to bring food to them. Most species of sponges stay in the same place for their entire lives.
All sponges have holes in their bodies that they suck water through, and as the water moves through the sponge filters out food and oxygen.
Some sponges grow bodies with a hard skeleton, while others have soft, flexible bodies. For a long time, humans have harvested soft-bodied sponges from the ocean and used them as tools for cleaning and other purposes. If you leave a portion of the sponge when you harvest it, sometimes it grows back, but often the entire animal dies.
Some countries have made it illegal to harvest wild sponges because they are worried about their sponge populations dying out. Many people now use sponges made from synthetic materials, and people have also begun growing sponges in ocean farms. Natural sponges are still available to people who want them, and wild sponges are protected from harmful harvesting practices.
This red finger sponge grows in Florida and the Caribbean Sea. It filters food and oxygen out of water that it moves through the holes in its body. The holes look like black dots in this photo. By Nick Hobgood
These natural sponges have been harvested and dried for humans to use. By Eli Shany
The above links plus:
Campbell, Andrew. Seashore Life. New York: Newnes Books, 1983. Pp. 30-31.
Gray, Susan H. First Reports: Coral Reefs. Minneapolis, MN: Compass Point Books, 2001. Pp. 21-23.
Kaplan, Eugene H. Field Guide to Southeastern and Caribbean Seashores. Boston: Houghton Mifflin, 1988.
Love, Carrie and Caroline Stamps, ed. Animals: A Children’s Encyclopedia. New York: DK Publishing, 2008. Pp. 226-228.