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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 phylum Porifera is further divided into classes mainly according to the composition of their skeletons: [17] [29] Hexactinellida (glass sponges) have silicate spicules, the largest of which have six rays and may be individual or fused. [17] The main components of their bodies are syncytia in which large numbers of cell share a single ...
The pinacoderm is composed of pinacocytes, flattened epithelial cells that can expand or contract to slightly alter the size and shape of the sponge. [1] It also contains porocytes, oval-shaped cells extending from the pinacoderm to the choanoderm (the body layer containing choanocytes).
Bolosoma stalked glass sponge. 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.
As members of the oldest phylum of metazoans, Suberites serve as model organisms to elucidate features of the earliest animals. [2] [3] [4] Suberites and their relatives are used to determine the structure of the first metazoans [2] and have been studied to determine how totipotency has replaced by pluripotency in most higher animals. [5]
A spongivore is an animal anatomically and physiologically adapted to eating animals of the phylum Porifera, commonly called sea sponges, for the main component of its diet. As a result of their diet, spongivore animals like the hawksbill turtle have developed sharp, narrow bird-like beak that allows them to reach within crevices on the reef to ...
Prior to the 1970s, stromatoporoids were most frequently equated with colonial hydrozoans in the phylum Cnidaria (which also includes corals, sea anemones, and jellyfish). They are now classified as sponges in the phylum Porifera, based on their similarity to modern sclerosponges. True Paleozoic stromatoporoids (sensu stricto) encompass seven ...
But some invertebrate paleontologists have placed them in an extinct, separate phylum, known appropriately as the Archaeocyatha. [11] However, one cladistic analysis [12] suggests that Archaeocyatha is a clade nested within the phylum Porifera (better known as the true sponges). True archaeocyathans coexisted with other enigmatic sponge-like ...