Volume 5 Number 6
Sponges and Corals Battle while Lane Snappers Look On,
near Bimini in The Bahamas
As we have learned in other ReefNews web pages and newsletters, corals and sponges are animals that live on the bottom of the ocean in shallow water in the tropics. Because these animals need space to live on the bottom of the ocean, they often fight with each other for living spaces. This picture shows a long, slow battle in progress between a Brain Coral and an Orange Boring Sponge.
Brain Corals are colonies of tens of thousands of tiny animals. Each animal is called a polyp. These tiny polyps build tiny "houses" where they hide during they day, and from which they extend their tentacles at night to catch food. These rows of houses make ridges on the surface of the coralhead, giving the Brain Coral colony its name. Be sure to learn all about these animals from the ReefNews Guide to Corals.
Sponges are animals that filter food out of the water. They attach to a spot on a coralhead, getting support and shelter from the skeleton built by the coral polyps. Some sponges, such as tube sponges, can build huge colonies that reach up into the water. Others, like the Orange Boring Sponge in this picture, spread out across the coralhead and burrow down into the coralhead.
So the Orange Boring Sponge and the Brain Coral are in a battle for space to live on the bottom of the ocean. The Orange Boring Sponge eats away at the skeleton of the coralhead, while polyps keep building the coralhead in a race keep the coralhead from being destroyed. This battle will continue until a Sea Turtle will come along and eat the sponge.
Notice the spot that has been eaten away on the coralhead on the right. This dead spot possibly was caused by another sponge in the past, but now the sponge is gone, possibly eaten by a turtle or some other animal.
Notice the pair of Lane Snappers swimming above this reef. Lane Snappers are identified by their white-silver bodies, thin yellow stripes, and black spots on their backs. Compare these Lane Snappers with the similar Bluestriped Grunts from e-ReefNews Volume 5 Number 2.
We saw all these animals at a reef near Bimini in The Bahamas.
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