spear swimming species family found west coast north_america san_diego california limited number harvested divers narrow west coast canada lives zone low tide mark depth metres soft sediment rock particularly areas strong current filter microscopic algae water passes gills preyed sea detect predators smell sight swim away opening closing organisms grow exterior shell forms relationship grows upper valve helps protect predators etymology scientific derived latin word greek short cape wool worn soldier meaning spear like latin spear description shell slightly shaped like fan able grow height centimetres normal adult size centimetres shell composed convex small number broad ribs covered blunt spines rounded near fine background colour white radial bands pale purple right valve usually underneath paler left annual growth rings visible concentric bands different irregular shell flaps anterior normally larger provides attachment single strong muscle closes shell long little ridges grooves known teeth function prevent moving sideways regard shells large cardinal teeth immediately instead lateral teeth lying lining inside mantle membrane covers gut internal organs seen round margins thick layer like sandwich filling fringed numerous short row tiny simple eyes close animal usually lies right valve exposed left valve colonial growing distinguished close relative pacific pink rounded small curved spines ribs rough texture pacific pink feels smooth glossy white interior shell near present pacific pink distribution habitat occurs naturally west coast north_america range extends san_diego southern california found areas sand gravel crushed shell depth metres known meadows rocky shores locations high currents biology anchors substrate threads unclear purpose serve help orient regard current optimal feeding possibility angle ready quick easily broken starts swim filter mantle separating passes water gills action large process litres water hour weight water gills moved mouth grooves pair mouth rejected particles formed wrapped ejected mantle cavity intervals rapid raised level diet found increase development time storage main muscle depleted energy transferred parted feeding edge mantle longer ones sensitive cells tip taste water allow react appropriately example smell taking action shorter ones forming ring way round edge mantle simple eyes tips eye contains lens concave spherical mirror eyes objects detect difference light darkness enabling snapped shut large threatening object nearby able detect size speed particles moving past current enabling open wide feed conditions suitable individuals male female mature years old usually live years breeding takes place summer released water column external larvae begin develop eggs days drift days growing maximum valve length inch larvae broad compound near mouth feeding organ bands running simple eyes rudimentary gills start developing 25th day foot visible 15th day projecting end foot develops 28th day crawling foot takes place 40th day course hours internal organs undergo rotation appear gills swimming benthic juvenile ecology animals feed include particularly star star sea swim escape predators repeatedly opening shutting action time close water expelled gap mantle dorsal animal moves margin form jet propulsion mantle margins detect approach enable action responds way predators feed genus usually relationship grows left valve orange purple brown provides camouflage deter predators attacking produce tend makes difficult strong grip tube feet needs force apart benefits fact living prevents buried sediment wild found grow larger size areas high laboratory study showed conditions sediment frequently stirred shells died living shells flourished study showed growth rates heavily significantly lower ones organisms grow shell boring parasitic species makes holes millimetres diameter valve common living surface valve include tube worms survey undertaken washington depth metres right valve heavily left clad left common tube worms encountered tubes worms organisms living dead tubes lower left valve equally able force open normally animals unable evade predators attached benefit defence response threats enables avoid predation presence reduce ability swim found chemicals discourage larvae settling nearby larvae settle shells way advantage ability swim fishery harvesting fishing west coast canada previous commercial fishery discontinued methods diving small maximum width metres minimum size limits set height shells millimetres millimetres pink framework research document published fisheries recommendations development dive fisheries
Chlamys hastata