During spawning events,horseshoe crab eggs are released from the female's oviducts,and fertilized by one or moremales.Eggs are shaped by the female into discrete clutches deposited in nests at depths of 10-20 cm o...During spawning events,horseshoe crab eggs are released from the female's oviducts,and fertilized by one or moremales.Eggs are shaped by the female into discrete clutches deposited in nests at depths of 10-20 cm on intertidal estuarinebeaches.Distinguishing between fresh eggs and the early developmental stages is obfuscated by the large amount of dense,opaque yolk.The first unambiguous confirmation of development is the formation of the rudimentary prosomatic appendages atthe 'limb bud' stage.Several days thereafter,the outer chorion is shed and the developing embryo expands and undergoes a seriesof molts within the clear inner egg membrane.The trilobite (first instar) stage thus attained may remain within the beach sedimentsfor several more weeks,until hatching is facilitated by environmental factors such as hydration,agitation,and osmoticshock that accompany the infiltration of seawater into the nests.Trilobites exhibit endogenous circatidal swimming rhythms thatare entrained by mechanical agitation,suggesting that peaks in larval swimming are timed to coincide with periods of high waterand the inundation of the nests.Larval swimming is limited and does not appear to result in long-distance dispersal.The limiteddispersal of the larvae has important implications for the population dynamics of relatively isolated populations.The rate of larvaldevelopment is highly plastic and is influenced by temperature,salinity,dissolved oxygen,and the presence of pollutants.Thebroad environmental tolerances of horseshoe crab embryos and larvae are important in understanding their current geographicdistribution and their evolutionary展开更多
基金supported by a series of awards from New Jersey Sea Grantsupport from the U.S. Army Corps of Engineers, Philadelphia Districtsupported by National Park Service Grants Nos.CA518099049 and PS 180060016
文摘During spawning events,horseshoe crab eggs are released from the female's oviducts,and fertilized by one or moremales.Eggs are shaped by the female into discrete clutches deposited in nests at depths of 10-20 cm on intertidal estuarinebeaches.Distinguishing between fresh eggs and the early developmental stages is obfuscated by the large amount of dense,opaque yolk.The first unambiguous confirmation of development is the formation of the rudimentary prosomatic appendages atthe 'limb bud' stage.Several days thereafter,the outer chorion is shed and the developing embryo expands and undergoes a seriesof molts within the clear inner egg membrane.The trilobite (first instar) stage thus attained may remain within the beach sedimentsfor several more weeks,until hatching is facilitated by environmental factors such as hydration,agitation,and osmoticshock that accompany the infiltration of seawater into the nests.Trilobites exhibit endogenous circatidal swimming rhythms thatare entrained by mechanical agitation,suggesting that peaks in larval swimming are timed to coincide with periods of high waterand the inundation of the nests.Larval swimming is limited and does not appear to result in long-distance dispersal.The limiteddispersal of the larvae has important implications for the population dynamics of relatively isolated populations.The rate of larvaldevelopment is highly plastic and is influenced by temperature,salinity,dissolved oxygen,and the presence of pollutants.Thebroad environmental tolerances of horseshoe crab embryos and larvae are important in understanding their current geographicdistribution and their evolutionary
