Short-spined crown-of-thorns starfish
Acanthaster brevispinus, the short-spined crown-of-thorns starfish, is one of the two members of the starfish genus Acanthaster, along with the much better-known A. planci, the common crown-of-thorns starfish.
Ca
CarnivoreA carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of a...
Cr
CrawlingOv
OviparousOviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
No
Not a migrantAnimals that do not make seasonal movements and stay in their native home ranges all year round are called not migrants or residents.
A
starts withThe body form of A. brevispinus is fundamentally the same as that of a typical starfish or seastar. Like A. planci, however, its distinctive traits include being disc-shaped, multiple-armed with multiple madreporites, flexible, prehensile, and densely spined, and having a large ratio of stomach surface to body mass. Its prehensile ability arises from the two rows of numerous tube feet that extend to the tip of each arm. In being multiple-armed, it has lost the five-fold symmetry (pentamerism) typical of starfish, although it begins with this symmetry in its life cycle.
Acanthaster brevispinus is readily distinguished from A. planci in that it has:
The short-spined crown-of-thorns starfish has been reported from the Philippines (western Pacific Ocean, southeast Asia), Great Barrier Reef (western Pacific Ocean, eastern Australia) and the Seychelles (western Indian Ocean). These are widely separated locations and it is not possible to accurately describe the geographic distribution of this species, except it is broad and sympatric with a significant part of the distribution of A. planci. The locations are also within the tropics or subtropics. The highest latitude from which it has been collected is at the southern part of the Great Barrier Reef.
All specimens have been collected from at least moderate depth: 18 m, 20+ m and 63 m in the Seychelles. A. brevispinus was not abundant at any of these localities, judging from the one or few collected, although this possibly is an artifact of the ways they were collected. Apparently, all were collected from soft substrates, not hard substrates like coral reef. Data are minimal on the benthic communities of which they are a part.
The Great Barrier Reef specimens used by Lucas and Jones came as an incidental bycatch of trawling inshore of the Great Barrier Reef off Townsville in the central zone of the reef. They came from a sandy substrate. Two invertebrates were also collected in the trawls: the scallops Amusium balloti and A. pleuronectes. Scallops would seem to be difficult prey for slow-moving starfish with their rapid swimming by 'flapping' their valves and with 'eyes' on their mantle edges. In the laboratory, however, the starfish were able to trap unrestrained scallops. They slowly approached the scallop over its hinge, where they were less visible, so when the scallop detected the starfish, its movements were towards and under the starfish's disk, where it could be trapped. Only a portion of attempts at trapping scallops were successful.
After trapping a scallop, the starfish fed and digested it while adopting a characteristic arched posture. A. brevispinus was fed commercial scallop meat as its standard laboratory diet, and they adopted the same arched feeding posture during feeding. This suggests scallops are a significant component of their normal diet, such that even the 'taste' of scallop meat triggers the distinct feeding behaviour. A. brevispinus, however, is quite omnivorous, at least according to observations in the laboratory.
