Sea UrchinsStrongylocentrotus purpuratusOvumLytechinusEmbryo, NonmammalianFertilizationOceans and SeasParacentrotusEchinodermataSperm TailSpermatozoaHemicentrotusMediterranean SeaSea AnemonesStrongylocentrotusGastrulaNorth SeaSea CucumbersMolecular Sequence DataStarfishEctodermZygoteSperm-Ovum InteractionsGene Expression Regulation, DevelopmentalArbaciaHyalinAmino Acid SequenceEgg ProteinsSeawaterBase SequenceBlastulaDyneinsMesodermPhylogenyBlastomeresEndodermLarvaCyclic ADP-RiboseSperm MotilityMicroinjectionsAcrosomeKelpVitelline MembraneNodal ProteinSpecies SpecificityCloning, MolecularHistonesCalcium CarbonateSequence Homology, Amino Acid