Bivalvia | 
Pectinida | 
Pectinidae
			
			
			
				Environment: milieu / climate zone / depth range / distribution range				
				
					Ecology				
				
			
			
				Benthic; depth range 0 - 80 m (Ref. 348), usually 0 - 30 m (Ref. 348).  Tropical			
			
			
				
			
			
			
				Indo-West Pacific.
			
			
			
			
			
				Length at first maturity / Size / Weight / Age
			
			
				Maturity: Lm ?  range ? - ? cm Max length : 14.0 cm ShL male/unsexed; (Ref. 348); common length : 11.0 cm SL male/unsexed; (Ref. 348)			
			
			
							
				
				
					
						Shell thin, medium to large sized (commonly exceeding to 10 cm in length), laterally compressed, almost circular in outline, gaping anteriorly and posteriorly.  Both valves somewhat convex, the right (lower) valve only a little more inflated and larger than the left (upper) valve.  Ears small, subequal in size and shape, with the right anterior ear faintly sinuated at anteroventral margin and devoid of ctenolium.  Surface of left valve with 2 broad and very shallow depressed areas radiating from the umbo to anteroventral and radial lines.  Interior of both valves with distinct radial ribs, usually in pairs, much narrower than the flat interspaces and becoming obsolete on umbonal area.  Right valve with 42 to 54 internal radial ribs (46 to 54 in the typical subspecies A. japonicum, and 42 to 48 in the southern A. japonicum balloti).  Colour:  outside of left valve reddish brown, with variable shades along the concentric growth marks; outer colour pattern of subspecies balloti also with small, yellowish and dark brown spots along radial lines on umbonal area and often with a few irregular, larger dark spots towards periphery.  Interior of left valve glossy to pale yellow externally and internally; subspecies balloti with an additional external brown scattering along some concentric growth marks.					
				
				
						
			
			
			
			
				
					On sandy to muddy bottoms of lagoons, often associated with brown seaweeds.  Sublittoral mainly from shallow waters to about 30 m, but also deeper to more than 80 m.  Can actively swim by clapping the valves when disturbed, with a speed of about 2 knots and for a distance of some 10 m (Ref. 348).				
			
			
			
			
			
				Life cycle and mating behavior				
					Maturity | Reproduction | Spawning | Eggs | Fecundity | Larvae				
			
			
				
					Sexes separate.  Spawning occurs in the cool season, from June to November.  Growth is relatively rapid (about 7 to 8 cm in the first year), but the number of individuals reaching a 3 or 4 years age is small, because of a high rate of natural mortality.				
			
			
			
			
			
				Poutiers, J.M. 1998 Bivalves. Acephala, Lamellibranchia, Pelecypoda. p. 123-362. In Carpenter, K. E. and V. H. Niem. 1998. FAO species identification guide for fishery purposes. The living marine resources of the Western Central Pacific. Volume 1. Seaweeds, corals, bivalves, and gastropods. Rome, FAO. (Ref. 348)
			
			
			
			
			
			
			
					
						IUCN Red List Status    
						 (Ref. 130435: Version 2025-1)
					
					
					
				
			
			
			
			
				CITES status   (Ref. 108899)
			
			
				
					Not Evaluated				
			
			
			
			
			
			
				
					Not Evaluated				
			
			
			
			
			
				Threat to humans  
			
			
				
					  Harmless				
			
			
			
			
			
			
			
			
				Human uses  
			
			
				Fisheries: commercial			
			
			
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					More information				
				
					 Trophic EcologyFood items (preys)
Diet composition
Food consumption
Predators
  Population dynamicsGrowth
Max. ages / sizes
Length-weight rel.
Length-length rel.
Length-frequencies
Mass conversion
Abundance
  Life cycleReproductionMaturityFecunditySpawningEggsEgg developmentLarvae   PhysiologyOxygen consumption
  Human RelatedStamps, coins, misc.
  				 
			 
			
			
			
				Internet sources
			
			
			
			
			
				Estimates based on models
			
			
			
									
						Preferred temperature  					
				 (Ref. 
115969): 18.7 - 29, mean 27.6 (based on 1304 cells).			
 
			
			
			
			
			
						
							
				
					
						Fishing Vulnerability  					
					
					
						Low vulnerability (10 of 100).