Classification
Porifera is one of the many different phylum of invertebrates. Like all invertebrates, it is classified as Metazoa. This is as far as this phylum has evolved. It is the most simple invertebrate as it has no symmetry, meaning that it lacks parts that correspond to another, or radial symmetry, meaning it can be cut down the center. The porifera is a diploblast which means it has two layers of cells. It is a multi cellular animal meaning that it could be cut up into pieces, and it would reform because the cells take on no specific identity. Diversity (or lack of) The only group in this phylum is sponges. Sponges have no mouth or anus but instead have pores all over their body. An example of some types of sponges are Hexactillida which have intricate patterns, Calcarea that have Calcium Carbonate skeletons, and Demospongiae which have silicate or Calcium-based fibers intermixed with soft tissues. These are just 3 of the 5,000 to 10,000 different possible species known. Life History Inside a sponge, there are large holes which expose its inner chamber to the outside. These holes are called oscula where small cells called choanocytes are attached to the side. The choanocytes have flagella that beat back and forth. This beating makes water and nutrients pump through the sponge like blood to a heart. Sponges feed and excrete waste by filtering the water and pumping out oxygen. Sponges can produce both asexually and sexually. Most sponges are hermaphrodites meaning they can act as both male and female. Because sponges are multi cellular and can be broken, budding can occur on the sponge and when it breaks off, it creates a new sponge. If a sponge produces sexually, one sponge will take on a male role and another will take on a female role. When the eggs are fertilized, they turn into larvae and swim off to ground themselves else where and become a new sponge. How sponges came to be was tested by a man named H.V. Wilson. He sifted a species of sponge and put the small pieces in a dish. After a while, he noticed they would collect together to make bigger sponges. He did this with more than one kind of sponge and realized on the same sponges combined with each other. This may mean that these multi cellular sponges started off as a lot of protozoans that happened to be together and formed Porifera Ecological Roles Sponges are filter feeding creatures that are vital to our ecosystem. While filter feeding, sponges pick up a lot of bacteria. This bacteria can improve the nitrogen coming out of the sponge to improve its own and the animals around its health. The bacteria can also control excess nitrogen levels which keeps the ecosystem balanced at all times. Human Impacts Sponges are often used as house hold sponges. Yes that's right, the one on your kitchen sink. Most of these sponges used by people are demospongiae. |
Cites used:
http://species-identification.org/species.php?species_group=caribbean_diving_guide&id=97&menuentry=groepen
http://tolweb.org/treehouses/?treehouse_id=4291
http://tolweb.org/treehouses/?treehouse_id=3431
http://species-identification.org/species.php?species_group=caribbean_diving_guide&id=97&menuentry=groepen
http://tolweb.org/treehouses/?treehouse_id=4291
http://tolweb.org/treehouses/?treehouse_id=3431