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The life cycle of echinoids is simple Reproduction is strictly confined to adult stages that generally involve the spawning of eggs and sperm freely into the seawater followed by the external fertilization Kelly 2000 Most echinoids are free spawners that produce a vast number of small yolk poor eggs that develop into planktonic feeding larvae known as echinopluteus in response to environmental factors that signal the availability of suitable benthic habitat Mc Edward et al 2007 During spawning the gonads release large quantities of eggs and sperm into the water for the increased chance of survival in the marine environment Bolton et al 2001 When sperm are added to the water the outer gelatinous layer around the egg dissolves and the sperm become attached to the jelly coat Tamaru et al 2010 A fertilization membrane lifts from the surface of the egg after about 3 minutes stretching the jelly layer and leaving a perivitelline space Zygotes were classified with the formation of the fertilization membrane around the circumference of the egg Kelly 2000 Said membrane started to form within 8 minutes after insemination With the penetration of the sperm it was pushed forward by its microtubules towards the center of the egg Rahman et al 2009
