Acarnidae | |
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Acarnus erithacus | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Porifera |
Class: | Demospongiae |
Order: | Poecilosclerida |
Family: | Acarnidae (Dendy, 1922) |
Genera | |
See text. | |
Synonyms [1] | |
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Acarnidae is a family of sponges belonging to the order Poecilosclerida. [2] It has a global distribution, although several genera occur primarily in colder temperate waters, and several have very restricted ranges. [3] It is estimated that there are several hundred species. [3]
Species form encrusting, massive, fan-shaped or digitate (small, un-splitting branches growing from a spreading base) growth forms that may burrow into the substrate. The species of many genera produce fistules. [3]
The outer skeleton is made of tylotes (long, slender megascleres with knobs at both ends) which may be modified to have a spined base as well as strongyles (megascleres with both ends blunt or rounded). These form tangential and/or paratangential tracts, often with an irregular or halichondroid arrangement. [3]
The inner skeleton is made of styles (megascleres with end pointed and the other end rounded) or modified styles. These form massive networks to create isodictyal (triangular meshes in which each side is one spicule long), isotropic (no differentiation into primary or secondary tracts, lines or fibers), anisotropic (primary and secondary tracts, lines or fibers) or more irregular skeletons. In encrusting forms they form plumose (skeletal structures radiate from primary fibres or spicule tracts) or hymedesmioid (monoaxon megascleres arranged singly with the heads fixed to a spongin base with the points directed outwards) skeletons instead. [3]
Spined spicules may be present or absent. When present, they take the form of acanthostyles (spiny styles) and/or unique cladotylotes (megascleres with 4-8 or even more axial branches and tubercles). Spined microscleres include palmate isochelaes and various toxas (microscleres that are curved like a bow). Both may, however, be lost in some species. Some genera also have other microscleres such as modified anisochelae such as the bipocillae (chellae with fused wings) of Iophon), microrhabd-like spicules (modified microxeas or microstrongyles) and diamond-shaped microxeas (modified toxas). [3]
The following genera are recognised: [2]
Spicules are structural elements found in most sponges. The meshing of many spicules serves as the sponge's skeleton and thus it provides structural support and potentially defense against predators.
Myxilla incrustans is a species of demosponge. It is an encrusting species and is usually yellow.
Crambeidae is a family of marine demosponges.
Crellidae is a family of marine demosponges in the order Poecilosclerida.
Homaxinella is a genus of sea sponges in the family Suberitidae. The type species is Homaxinella balfourensis.
Homaxinella balfourensis is a species of sea sponge in the family Suberitidae. It is found in the seas around Antarctica and can grow in two forms, either branching out in one plane like a fan or forming an upright club-like structure.
Potamolepidae is a family of freshwater sponges, with seven genera:
Agelas dispar is a species of demosponge in the family Agelasidae. It lives on shallow-water reefs in the Caribbean Sea and around the West Indies.
Dragmacidon is a genus of sponges in the family Axinellidae, first described in 1917 by E.F.Hallman .
Acanthochaetetidae is a family of sponges belonging to the order Clionaida. It is largely extinct, but contains two extant genera, each of which are represented by single extant species.
Iophon is a genus of sponges belonging to the family Acarnidae. The genus has a cosmopolitan distribution.
Coelosphaeridae is a family of sponges belonging to the order Poecilosclerida. Species are found across the globe.
Acarnus is a genus of sponges belonging to the family Acarnidae. The genus has almost cosmopolitan distribution.
Hamacantha is a genus of sponges in the family Hamacanthidae. This species in this genus differ from those in the other genera in this family through the presence of diancistras, distinctive microscleres. These are thought to aid in framing the skeleton by joining monactine megascleres. This genus contains 30 species in three subgenera.
Mycale anisochela, the brain sponge, is a species of demosponge from South Africa and Namibia.
Ectyonopsis is a genus of demosponges in the family Myxillidae. They are mostly known from the waters surrounding Australia and from the Southern Ocean.
Polymastia bouryesnaultae, the knobbly sponge, is a small and cryptic species of demosponge from South Africa and Namibia.
Penares is a widely distributed genus of demosponges.
Tetilla is a genus of demosponges in the family Tetillidae. It is widely distributed. They are mainly found in deeper habitats.
Monanchora is a genus of demosponges belonging to the family Crambeida. The genus contains 18 species, which have been researched for their potential use in medicine.