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Sponges contain genes very similar to those that contain the "recipe" for the post-synaptic density, an important signal-receiving structure in the neurons of all other animals. However, in sponges these genes are only activated in "flask cells" that appear only in larvae and may provide some sensory capability while the larvae are swimming.
Demosponges (Demospongiae) are the most diverse class in the phylum Porifera. They include greater than 90% of all species of sponges with nearly 8,800 species worldwide (World Porifera Database). [5] They are sponges with a soft body that covers a hard, often massive skeleton made of calcium carbonate, either aragonite or calcite [citation ...
The calcareous sponges [2] [3] (class Calcarea) are members of the animal phylum Porifera, the cellular sponges. They are characterized by spicules made of calcium carbonate, in the form of high-magnesium calcite or aragonite. While the spicules in most species are triradiate (with three points in a single plane), some species may possess two ...
The following is a list of the classes in each phylum of the kingdom Animalia. There are 107 classes of animals in 33 phyla in this list. However, different sources give different numbers of classes and phyla. For example, Protura, Diplura, and Collembola are often considered to be the three orders in the class Entognatha. This list should by ...
Marine invertebrates are animals that inhabit a marine environment apart from the vertebrate members of the chordate phylum; invertebrates lack a vertebral column. Some have evolved a shell or a hard exoskeleton. The earliest animals may belong to the genus Dickinsonia, [2] 571 million to 539 million years ago. [3]
Of this group only surviving sponges, which belong to the phylum Porifera, and Trichoplax in the phylum Placozoa. Parazoa do not show any body symmetry (they are asymmetric); all other groups of animals show some kind of symmetry. There are currently 5000 species, 150 of which are freshwater. The larvae are planktonic and the adults are sessile.
In both the non-animals and the comb jellies, researchers found 14 groups of genes located on separate chromosomes. But in the sponges, researchers found that those 14 groups had been rearranged ...
Hexactinellid sponges are sponges with a skeleton made of four- and/or six-pointed siliceous spicules, often referred to as glass sponges. They are usually classified along with other sponges in the phylum Porifera , but some researchers consider them sufficiently distinct to deserve their own phylum, Symplasma .