Structure of Sponge Reefs
Each living sponge on the surface of the reef can be over 1.5 m tall. The reefs are composed of mounds called “bioherms” that are up to 21 m high, and sheets called “biostromes” that are 2–10 m thick and may be many km wide.
Each sponge in the order Hexactinosa has a rigid skeleton that persists after the death of the animal. This provides an excellent substrate for sponge larvae to settle upon, and new sponges grow on the framework of past generations. The growth of sponge reefs is thus analogous to that of coral reefs. The tendrils of new sponges wrap around spicules of older, deceased sponges. The tendrils will later form the basal plate of the adult sponge that firmly anchors the animal to the reef.
Deep ocean currents carry fine sediments that are captured by the scaffolding of sponge reefs. A sediment matrix of silt, clay, and some sand forms around the base of the sponge bioherms. The sediment matrix is soft near the surface, and firm below one metre deep. Dead sponges become covered in sediment, but do not lose their supportive siliceous skeleton. The sponge sediments have high levels of silica and organic carbon. The reefs grow parallel to the glacial troughs, and the morphology of reefs is due to deep currents.
Read more about this topic: Sponge Reef
Famous quotes containing the words structure of, structure and/or sponge:
“A special feature of the structure of our book is the monstrous but perfectly organic part that eavesdropping plays in it.”
—Vladimir Nabokov (18991977)
“Vashtar: So its finished. A structure to house one man and the greatest treasure of all time.
Senta: And a structure that will last for all time.
Vashtar: Only history will tell that.
Senta: Sire, will he not be remembered?
Vashtar: Yes, hell be remembered. The pyramidll keep his memory alive. In that he built better than he knew.”
—William Faulkner (18971962)
“Alas for the affairs of men! When they are fortunate you might compare them to a shadow; and if they are unfortunate, a wet sponge with one dash wipes the picture away.”
—Aeschylus (525456 B.C.)