Sponge - It's What's for Dinner!
Yes, sponges have to eat to survive, remember they are animals. But, unlike the feared cousin, the Mediterranean sponge, most sponges consume microorganisms in the water. A sponge has small openings knows as ostia which allow microorganisms to enter the sponge. Then as the water moves through the central core of the sponge, the flagella (like little arms) reach out and grab the microorganisms that look tasty. Then, the water moves out the hole at the top of the sponge called the osculum. It is said that the amount of water filtering through a sponge can be 20,000 times its volume in as little as 1 day. WOW! That's a lot of water.
Then, there is the Mediterranean sponge which wonders the world's ocean floors in search of its next meal. This sponge very carefully and inconspicuously traps, envelops crustaceans with tiny hook-shaped filaments on its surface. Then it digests the unsuspecting victim.