Saturday 16 January 2016

ECHINODERMATA PHYLUM

*habitat-all are marine
*body form-unsegmented, star shaped, spherical or cylindrical.
*spine and pedicellariae- many echinoderm bear spine pincer like pedicellariae.
*symmetry-bilateral in larvae and  pentamerous in adults.
*germ layer-triploblastic
*level of organisation-organ system level
*body wall-epidermis is single layered and ciliated
*body cavity-enterocoelic coelom
*ambulacral system( water vascular system)-presence of ambulacral system is the characteristic feature of phylum echinodermata.
*digestive tract-incomplete digestive tract
*respiratory organ-dermal or papulae, peristominal gills, genital bursae.
*excretory organ- excretion through diffusion
*nervous system-it consists of nerve ring
*sexes and fertilization-generally sexes are separate,fertilization is external
*development- indirect.
*classification-
  1. Asteroidea-Asterias
  2. Ophiuroidea-Ophiothrix
  3. Echinoidea-Echinus
  4. Holothuroidea-Cucumaria
  5. Crinoidea-Antedon




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