Porifera | Sponges
Porifera, or sponges, are multicellular organisms with many pores that filter water. Most sponges live in marine environments, however, some live in brackish environments and about 150 species live in freshwater. Sponges were the first creatures to branch off of the evolutionary tree, which means they are the sister to all other living creatures. Lacking circulatory, digestive, and nervous systems, sponges rely on filtering water unidirectionally to remove wastes from their bodies. Sponges are also immobile species with shapes adapted for the best filtration of water, which rely primarily on filter feeding, however, some species host photosynthesizing microorganisms that provide them with food and oxygen.
Porifera are able to reproduce asexually and sexually. Some porifera can reproduce by regenerating themselves once they are broken off either by the water current or predators. In other species the male releases the sperm into the water, and this goes into the female porifera. After fertilization, the larvae are released. They float until they stick to a surface and continue their growth.
Most porifera are filter feeders that eat tiny organic debris, particles, and plankton that they filter from the water. Porifera are not picky and will eat whatever the current from the ocean brings along, ranging from large particles to tiny organisms.
Porifera move very slowly, typically less than a millimeter a day. Some porifera may become fixed onto a surface and not move. During reproduction larvae are released and will float in the water, but are not particular in their direction.