![]() The inner layer is called the coanoderm, and it is made up of cells called choanocytes. The outer layer of the sea sponge is called pinacoderm, and it is made up of cells very similar to epithelial (skin) cells, called pinacocytes. Porifers are made up of two layers of cells, separated from each other by an interior space. Some species are capable of adapting their shape to the environment, changing their appearance depending on the inclination of the substrate, or if they collide with a rock. Visually they are sack-shaped and, although the shape can vary between different sea sponges, they all have a similar body structure. Perhaps morphologically the most outstanding thing about sponges is that they do not have body symmetry. ![]() Its most important characteristic, which gives its name to this group of animals (poriferous), is that their bodies are covered by a succession of pores and channels, through which water passes, and that they serve to obtain their food and oxygen needed to live. ![]() There are about 9,000 different species of sponges around the world, of which only 150 species live in fresh water, the rest of the sponges live in the sea. Until 1765 it was thought that sponges were plants, until it was discovered that they possess internal currents and that they perform intracellular digestion.Īnother fact that had gone unnoticed until recently is that sponges can move, but they move so slowly (about 4 mm a day) that the fact had gone completely unnoticed. Its main characteristic is that its body is completely full of pores through which water circulates, which is why they are called «poriferous». ![]() Porifers (sea sponges) are invertebrate animals known as sponges.
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