English name: Sea urchin Scientific name: Psammechinus sp. Familia: Echinidae Classis: Echinoidea Phylum: Echinodermata Regnum: Animalia
The unfertilized egg is surrounded by a yolk membrane (=vitelline membrane). The yolk material is equally spread over the cytoplasm. Therefore this type of egg is called isolecithal (iso= equal; lecithal = yolk). To next stage.