Contrary to popular belief, sponges do not live in a pineapple under the sea, but rather an array of different environments.  Most Calcarea sponges live in shallow coastal areas, with the most variety in populations found in tropical areas. The Great Barrier Reef in Australia is an excellent example of the ideal Calcarea habitat.  Hexactinellids are almost exclusively found at extreme depths, with the highest living species living at the maximum diving depths for SCUBA divers. Because of the extreme depths that Hexactinellids live, not much is known about them as they are difficult to study in their natural environments.  Demosponges, being the most abundant type of sponges, are found almost everywhere in the ocean. From up on the coastal planes to down in the abyss of undersea trenches, and everywhere in between, even including Spongillidea, a Demosponge found in freshwater environments. Demosponges are the most widely recognized and studied group of sponges.  |