Classification of Echinodermata
Dr. D.Aruna Kumari
SKR & SKR College W A Kadapa Email. Id : [email protected] Classification of Phylum Echinodermata LEARNING OUTCOMES ➢ Introduction and detailed information about the classification ➢ About Subphyla ➢ Classes ➢ Best examples
https://biodiversitybasics.files.wordpress.com/2014/03/ echinoderm_diversity.gif Nearly 6000 Echinoderm species are distributed all over world. They are classified based on their body structure, which shows a lot of difference in nature of the skeleton. The classification is adopted from LH Hyman. 1. Pelmatozoa 2. Eleutherozoa Sub Phy: Pelmatozoa (Gr: “pelmatos” means stalk) These are mostly extinct animals . Lead Sedentary life. Body is attached surface by an aboral stalk. Mouth & Anus are present on the oral surface facing upwards. Tube feet are with out suckers They are primarily meant for food capturing. Pelmatozoa has only one living class i.e Crinoidea Crinoidea (Gk. Crinon- lilly, eidos- form)
These are commonly known as sea lillies. Marine and sedentary animals. They attach to the substratum on aboral side with long peduncle supported by cirri. Mouth is surrounded by five triangular plates. Five arms are present. Each arm is divided in to two and bears pinnules. Madreporite, spines and pedicellaria are absent. Tubefeet is without suckers.
https://live.staticflickr.com/4740/391143971 Unisexual animals. Fertilization is external. 44_059aed83a1_b.jpg Larva is also known as doliolaria. Ex: Antedon, Trilochinus Sub Phy: Eleutherozoa (“eleutheros” means free) Mostly living echinoderms. They are free living forms. Stem or stalk is absent . Body structure is usually pentamerous. Mouth is present on oral surface. It is in downwards position. Anus is present on the aboral surface. Tube feet with suckers are and acts as locomotory organs. Ambulacral grooves are closed except in Asteroidea It is divided into 4 classes Asteroidea Ophiuroidea Echinoidea Holothuroidea Class 1. Asteroidea (Gk. aster- star, eidos- form)
Star fishes or sea stars are included in this class. All are marine animals. Body is pentagonal in shape. The arms are not clearly demarcated from the central disc. Tubefeet and papulae are the respiratory organs. Tube feet come out side through ambulacral groove during locomotion. Madreporite, anus, spines and pedicellaria are present on aboral side with two jaws. Ambulacral grooves are open, they are present on oral side of the arms. https://i.pinimg.com/originals/d5/e6/8b/d5e68b1d916f728e Development includes Bipinnaria and Brachiolaria larval . f8120d730635c048.jpg Ex: Asterias, Solaster. Class 2. Ophiuroidea (Gk. Ophis- snake, Oura- tail, eidos- form)
Body arms in these animals will appear like snake tail structures. These are commonly known as brittle stars. The skin is leathery, with dermal plates and spines . Brittle stars tend to be secretive, living on hard bottoms where little or no light penetrates. Internal calcium carbonate skeleton is present in the mineral form of calcite. Ambulacral grooves are closed. Anus is absent. Tubefeet is without suckers. Pedicellaria are sbsent.
Ophiopluteus larval stage is present. https://ars.elscdn.com/content/image/1-s2.0- S1055790316304067-fx1.jpg Ex: Ophiothrix, Ophiura Class 3. Echinoidea (Gk. echinos- hedgehog, eidos- form) Sea urchins, heart urchins, sea biscuits and dollars are included in this class. They possess spherical, globular, disk or heart shaped body. The body is covered by hard calcareous test. Three jawed pedicellariae are present. Madreporite and Anus are present on aboral side. Ambulacral grooves are closed. Tube feet bears suckers. Specialized gills called peristomial gills occur in sea urchins. Aristotle lantern – 5 jawed masticatory apparatus . https://upload.wikimedia.org/wikipedia/commons/ These are unisexual animals. 4/4e/ Echinus_esculentus_Koster.jpg Development includes Echinopluteus larval stage Ex. Echinus, Clypeaster Class 4. Holothuroidea (Gk.Holothurion- sea cucumber, eidos- form)
These are commonly called as sea cucumbers. All are marine skin is very soft and smooth. Oro- aborally extended cylindrical body is present. Papulae and pedicellariae are present. Contractile tentacles are introvert and present around the mouth. Tube feet is without suckers. Calcareous spicules and spine are the skeletal structures. https://c8.alamy.com/comp/CBMTPR/plankton-feeding-sea- Cloacal respiratory tree is present. cucumber-cucumaria-sp-piran-adriatic-sea-slovenia-CBMTPR.jpg Auricularia is the larval stage. Ex: Holothuria, Cucumaria Summary
There are 6000 living echinoderm species. Divided into two sub Phyla . 1. Pelmatozoa --Sedentary 2. Eleutherozoa-- Free living Pelmatozoa Crinoidea - Sea lilies - Ex: Antedon , Trylocinas ( Calyx is in the form of calcified cup ) Eleuthirozoa 1. Asteroidea - Sea stars - Ex: Asterias, Solaster (papulae/ Tube feet for respiration) 2. Ophiuroidia - Brittle stars - Ex: Ophiothrix, Ohiura ( special gills, genital Burfa) 3. Echinoidea - Sea urchins – Ex: Echinus , Clepaster. (Aristotle Lantern) 4. Holothuroidea - Sea cucumbers - Ex: Holothuria, Cucumeria (skin is smooth and soft , respiratory trees.)
ATTRIBUTES AND ACKNOWLEGEMENTS
▪ https://biodiversitybasics.files.wordpress.com/2014/03/echinoderm_diversity.gif ▪ https://live.staticflickr.com/4740/39114397144_059aed83a1_b.jpg ▪ https://i.pinimg.com/originals/d5/e6/8b/d5e68b1d916f728ef8120d730635c048.jpg ▪ https://ars.elscdn.com/content/image/1-s2.0-S1055790316304067-fx1.jpg ▪ https://upload.wikimedia.org/wikipedia/commons/ 4/4e/ Echinus_esculentus_Koster.jpg ▪ https://c8.alamy.com/comp/CBMTPR/plankton-feeding-sea-cucumber-cucumaria-sp-piran- adriatic-sea-slovenia-CBMTPR.jpg
▪ http://www.biozoomer.com/2016/01/echinodermata-chahacters-classification.html
▪ Invertebrates and Cell biology Telugu academy Hyderabad