Amphidiscosida
Order of sponges
From Wikipedia, the free encyclopedia
Amphidiscosida (sometimes spelled Amphidiscosa)[2][3] is an order of hexactinellids (glass sponges). The Amphidiscosida are commonly regarded as the only living sponges in the subclass Amphidiscophora.[4][5]
Schulze, 1886
Schrammen, 1924[1]
| Amphidiscosida Temporal range: | |
|---|---|
| |
| Specimen of Pheronema carpenteri on exhibit in Naturmuseum Senckenberg | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Porifera |
| Class: | Hexactinellida |
| Subclass: | Amphidiscophora Schulze, 1886 |
| Order: | Amphidiscosida Schrammen, 1924[1] |
As the name implies, the Amphidiscosida are characterized by a special type of microsclere (microscopic spicules): amphidiscs. Amphidiscs are rod-like spicules with an equal-sized umbel (a whorl of backswept hooks) at each end. The skeleton is primarily formed by megascleres (large spicules). In living species, most megascleres are pentactinal (five-rayed), though fossil species often have a more diverse set of megascleres.[2] Amphidiscosids are often covered with prostalia (bristles), formed by single-rayed spicules. In a few species, basalia (long rooting bristles) in the lower part of the body are bundled together to suspend the body above the seabed as an anchoring structure.[2][6]
The oldest fossilized amphidiscs are from the Carboniferous, but sponge fossils with spicules similar to Amphidiscosida have existed since the Cambrian period.[2][3] Three families still flourish in deep marine waters today.
Families
- Hyalonematidae Gray, 1857[7]
- Monorhaphididae Ijima, 1927[8]
- †Pattersoniidae Miller, 1889 [Middle Ordovician–Upper Ordovician][2]
- †Pelicaspongiidae Rigby, 1970 [Lower Ordovician–Triassic][2]
- Pheronematidae Gray, 1870[9]
- †Stiodermatidae Finks, 1960 [Lower Cambrian–Permian][2][3]
