Sponge

Parazoa/Ahistozoa sans Placozoa

Sponges, a members of a ; meaning 'pore bearer', are a basal animal clade as a sister of the Diploblasts. They are multicellular organisms that hold bodies full of pores as alive as channels allowing water to circulate through them, consisting of jelly-like mesohyl sandwiched between two thin layers of cells.

Sponges throw unspecialized cells that can transform into other types as living as that often migrate between the main cell layers together with the mesohyl in the process. Sponges do not have nervous, digestive or circulatory systems. Instead, near rely on maintaining a fixed water flow through their bodies to obtain food and oxygen and to remove wastes. Sponges were first to branch off the evolutionary tree from the last common ancestor of all animals, creating them the sister group of all other animals.

Distinguishing features

Sponges constitute the phylum Porifera, and have been defined as sessile metazoans multicelled immobile animals that have water intake and outlet openings connected by chambers lined with choanocytes, cells with whip-like flagella. However, a few carnivorous sponges have lost these water flow systems and the choanocytes. All asked well sponges can remold their bodies, as near types of their cells can continue within their bodies and a few can conform from one type to another.

Even if a few sponges are excellent to produce mucus – which acts as a microbial barrier in all other animals – no sponge with the ability to secrete a functional mucus layer has been recorded. Without such(a) a mucus layer their alive tissue is included by a layer of microbial symbionts, which can contribute up to 40–50% of the sponge wet mass. This inability to prevent microbes from penetrating their porous tissue could be a major reason why they have never evolved a more complex anatomy.

Like cnidarians jellyfish, etc. and ctenophores comb jellies, and unlike all other call metazoans, sponges' bodies consist of a non-living jelly-like mass mesohyl sandwiched between two main layers of cells. Cnidarians and ctenophores have simple nervous systems, and their cell layers are bound by internal connections and by being mounted on a basement membrane thin fibrous mat, also known as "basal lamina". Sponges have no nervous systems, their middle jelly-like layers have large and varied populations of cells, and some types of cells in their outer layers may stay on into the middle layer and conform their functions.