Rossella antarctica
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| Rossella antarctica | |
|---|---|
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Porifera |
| Class: | Hexactinellida |
| Order: | Lyssacinosida |
| Family: | Rossellidae |
| Genus: | Rossella |
| Species: | R. antarctica |
| Binomial name | |
| Rossella antarctica Carter, 1872 | |
| Synonyms[1] | |
| |
Rossella antarctica is a relatively small species of glass sponge. It is widely distributed in the southern hemisphere, particularly in the Antarctic and sub-Antarctic regions.
Spicules
This off-white to grey sponge may grow up to 300 mm (12 in) long.[2] It has a semispherical to ovoid form with a large, deep oscule on the upper surface.[2][3] The upper part also has the largest diameter of the organism.[3] The body is dense and contains relatively few canals.[4] The whole surface is covered with long, hair like spicules that may protrude up to 30 mm (1.2 in) from the surface.[2] These spicules are most dense at the base, where they entangle to form a stalk that attaches the sponge to the substrate.[5]
The following spicules make up the skeleton of this species:[3][5]
- Robust diacts (spicules with two rays radiating in different directions from a single origin point) that may be up to 120 mm (4.7 in) long. They are longer in the lower third of the sponge. Clusters of four to seven spicules protrude from the surface, pointing upwards in the upper portions and downwards in the lower portions.
- Rough pentacts (five rayed spicules with perpendicular rays) covered in spines. They are hooked towards the end. They are situated just below the surface, forming the velum that is typical of this genus.
- Long and slender internal diacts. The ends are alightly rough and rounded and swollen.
- Robust spindle-like internal diacts with rough ends.
- Spined diacts with bunt or swollen ends. There may or may not be a central bulge.
- Oxyhexasters (spicules with six branching rays that end in sharp points) with short, spined rays.
- Slightly rough discohexasters (spicules with six branching rays that end in rounded discs).