BIOL 1101 Lecture Notes - Lecture 93: Spongin, Mesohyl, Sponge
27 Jun 2016
School
Department
Course
Professor
Document Summary
The simple sponge body wall consists of an inside and an outside layer of cells, with a gelatinous area called the mesohyl between them. Spicules are one of the distinctive features of sponges, and their only fossils. These structures are composed of calcium carbonate, silica, or a rubbery protein called spongin, and they support and protect the animal. Asbestopluma also uses spicules to capture its prey. Another, puzzling part of sponge anatomy is an enormous number of bacteria-- maybe up to 40% of the sponge volume may be prokaryotic cells. These species of bacteria are not found in the surrounding water, but are confined to sponges, and seem to be the same all over the world. We don"t know what the bacteria do for the sponges or vice versa. Eggs and sperm are usually derived from collar cells. The zygote develops into a free-swimming microscopic larva which eventually settles down onto a substrate and forms the familiar sessile creature.
