A Yellow Tube Sponge grows on a sand flat at East Chute. A sponge is an animal. It is made of a layer of cells that build a wall in the shape of a tube or bowl. These cells pump water through the sponge's wall, allowing the sponge to capture microscopic plankton for food. This Yellow Tube Sponge was living at a depth of 30 feet. It was 2 feet tall, with tubes 5 inches across.
The Yellow Tube Sponge shows off its pumping ability. Here, a researcher introduces a small amount of yellow vegetable dye, making a small yellow cloud in the water next to the sponge. Quickly, the sponge pumps water through its body and out the hole at the top of its tube. The moving water carries the yellow dye, and you can see the dye moving with the water. Before long, all the dye is removed from the base of the sponge and is ejected from the sponge's chimney. This entire sequence of photographs covered only 1 minute. The sponge pumps so much water that you sometimes can feel the exhaust by placing your hand near the top of the sponge's tube.
East Chute is a reef on the north side of Cayman Brac.