Sponges are a super ancient lineage of organisms, in fact they are soooo old they were one of the first organisms to branch off in the evolutionary tree, meaning they were here well before all other animals. Sea Sponges first evolved over 600 million years ago and they have remained unchanged that entire time. Sea Sponges are an odd looking organisms and if you have never seen one before, you could describe it dozens of different ways. Some are small, some are huge, some look like plants, others look like rocks. They are usually brilliant colors and are found underwater. But, given all that description it is still rather hard to figure out what a sponge is. Sea Sponges are the simplest organisms and they are called filter feeders. They have specialized cells that filter nutrients and debris out of the water and they actually kind of look like sponges.
Sea Sponges have no brains, no nervous system and no digestive system! The Ancient Greeks thought they were half animal and half plant and modern scientist thought that for a long time as well. To put it the most simply defenders, sea sponges are the simplest living organism on the planet. But, just because they are simple doesn’t mean that they aren’t useful. To find out all the ways sponges are important - check out the Working With Others tile in the kids zone.