Amusium pleuronectes


Amusium pleuronectes is a species of bivalve belonging to the family Pectinidae, the scallops, and is commonly known as the Asian moon scallop. It is native to the West Pacific.
One subspecies is recognized, being Amusium pleuronectes okinawaensis Masuda, Sato & Shuto, 1986.
This scallop is consumed throughout its range, with efforts being made to establish aquaculture of the species.

Description

Unlike those of the genus Pecten, the two near-circular valves of A. pleuronectes are nearly symmetrical, with the lower or right valve being slightly deeper than the upper or left valve. The two very smooth valves are also differently colored, with the left valve being some shade of pinkish-brown and the right valve white. Individuals are often long, and a maximum shell height of is reported.
There are 22 to 34 internal radial ribs on the shell; the supposed southern subspecies A. pleuronectes australiae apparently has 22-24 ribs, fewer than the nominate subspecies.

Biology

A. pleuronectes ranges in depth from, and often aggregates in large "schools". This species is benthic, but is one of a few species of scallop which are considered gliders, which swim more efficiently than most other species ; the flattened valves allow the scallops to glide during a level swimming phase. Other species with this niche include members of Adamussium, Placopecten, and Ylistrum. The convergent evolution of these species is so extensive that the species of Ylistrum were historically considered part of Amusium, and were only recognized as distinct through analysis of DNA and close examination of internal ribbing patterns.
Being filter feeders, these scallops consume diatoms such as Isochrysis galbana, Tetraselmis tetrahele, and Chaetoceros sp..
A. pleuronectes is protandrous, and reproduces throughout the year with a major peak in February and a minor peak between July and September. First maturity occurs around in shell height.

Relation to humans

A. pleuronectes is targeted by fisheries; peak season in the northern Philippines is April-June. They are edible and sold at wet markets throughout its range, such as Malaysia, and Indonesia. In Hong Kong, the meat is dried and sold for cooking double-stewed soup.
Aquaculture has been attempted for this species; natural spawning in controlled conditions were more effective than attempting to induce spawning behavior.