Astrostole scabra
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| Astrostole scabra | |
|---|---|
 | |
| Astrostole scabra | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Echinodermata |
| Class: | Asteroidea |
| Order: | Forcipulatida |
| Family: | Asteriidae |
| Genus: | Astrostole |
| Species: | A. scabra |
| Binomial name | |
| Astrostole scabra Hutton, 1872 | |
Astrostole scabra, commonly called the seven-armed starfish, is a sea star in the family Asteriidae, native to New Zealand, eastern Australia and southern Australia.[1] A frequent inhabitant of the intertidal zone also seen attached to wharf piles, it is among the larger sea-stars found in New Zealand. Adults often prey on mussels, forcing the shells open by applying pressure for long periods with the tube feet.
With a diameter of up to 350mm in subtidal forms, the colouration of A. scabra varies from orange through dark red to brown, or light blue to grey. The dorsal surface is covered in speckled plates, from the center of which protrude one or two short, stubby white spines which are specialised ossicles. These spines are blunt on top, becoming sharper and sometimes longer on the sides of the arms. Spines can appear blue in juveniles.[2]
The madreporite is not obvious. Tube feet are a combination of off-white and bright orange.
Intertidal individuals are generally smaller with thicker dermal plates, allowing them greater protection when being tossed about by waves. Despite this they are still found to be more damaged than subtidal individuals.[3]
Habitat
A common inhabitant of the rocky reef subtidal or the rocky shore intertidal, adult seven-armed seastars have been found down to 150m.[2] A. scabra has unique roaming habits – there is never a permanent home. Therefore, migratory and resident A. scabra in a location all result from random movement. Juveniles are more adventurous than adults in the coastal intertidal - they show considerable movement patterns within the intertidal and shallow sublittoral zones, not venturing beyond 20m in depth.[3]