PORIFERA: SPONGES
orange elephant ear sponge:Agelas clathrodes
Porifera, commonly known as sponges, are the simplest animals on earth. In fact, they were originally thought to be plants! However, they were reclassified...
...as animals because of their inability to create their own food. Unlike most animals, sponges are sessile. This means they are unable to move. They have no symmetry at all. Each cell takes up its own food though the cell membrane, since they have no organs or true tissues. Also unlike most animals, sponges can reproduce not only sexually but asexually as well. They are hermaphrodites, which means they can produce both egg and sperm, but a sponge’s egg cannot be fertilized by its own sperm. To perform this process, the sponge releases sperm into the water. The sperm is drawn into another sponge, where it fertilizes an egg to form a larva. The larva has cilia, which it uses to swim out of the sponge and settle on a surface to develop. Asexual reproduction occurs when a bud forms, then falls from the parent sponge to develop on its own. Sponges can also use a form of asexual reproduction called regeneration, where pieces of a sponge grow new parts to replace lost ones. I find it interesting that although not many people take time to notice them, sponges actually are a large part of the ocean ecosystem. Not only do they filter the ocean water, but animals such as worms, shrimp, snails, and sea stars inhabit sponges and animals such as snails, sea stars, and fish feed on them. Chemicals produced by sponges are also being used to fight bacteria, fungus, and viruses.