Transcript m5zn_c86f8afb63f50ac

Radially symmetrical.
 Have dermal skeleton which consists of
calcareous ossicles that may develop into
spines.
 With water vascular system which connect
with exterior by a pore(madreporite).
 With tube feet which mainly serve
locomotion but may alsoo assist in
sensation,respiration and food collection.
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Ph. Echinodermata
C1:Ast C2:Op
hieroidea uroidea
ex.Star Ex.Brittl
e star
fish
C3:Ec
hinoidea
C4:Holothu C5:Crinoi
-roidea
-dea
ex.Sea
ex:Sea
ex:Sea
cucumber
feather
urchin
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Star shaped.
The mouth opens on lower side(oral
surface)and anus,if present,on the upper
side(aboral surface)
The arms are not sharply marked off from
the central disc.
Each arm has an open (ambulacral
groove)which contains raws of tube feet
ending with suckers.
Pedicellari present.
Madreporite present on aboral surface.
Ex. Asteropecten sp. (Star fish)
A series of tube feet project in 2 raws along
each ambulacral groove,the terminal tube
foot or tentacle on the tip of each arm has
a pigmented spot(the eye) at its base(light
sesitive).
 The skin is covered with calcareous
plates(ossicles) and on these plates arise
spines of different sizes.
 Very small spines(pedicellaria)serv eto
clean the body surface
 On the aboral surface,near the periphery of
the disc there is the madreporite.
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Star shaped with arms sharply marked off
from the central disc.
 The ambulacral grooves are closed and
covered by ossicles.
 Tube feet without suckers.
 No pedicellaria.
 Madreporite on the oral surface,no anus.
 Ex. Ophicoma sp. (Brittle star)
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On the oral surface,there is the mouth
opening surrounded by 5 buccal
plates,one of them is modified into
madreporite.
 The arms are surrounded with 4
longtudinal raws of skeletal plates and 2
raws of tube feet project between
them(sensory and respiratory).
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With compact skeleton without arms.
 Ambulacral grooves covered with
ossicles.
 Tube feet ending with suckers.
 Anus and madreporite are aboral.
 Pedicellaria well developed.
 Ex. Tripneustes sp. (Sea urchin)
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Body is divided into 10 areas between the 2
poles,5 ambulacral areas containing the
tube feet and the other 5 are the inter
ambulacral areas with spines and with out
tube feet.
 On the oral pole,there is the mouth
surrounded by 5 pairs of sensory buccal
tube feet in a circle.
 There are also 5 pairs of branchiae help in
gas exchange.
 At the aboral pole,there is a central circular
membrane known as the periproct through
which the anus open eccentrically.
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The skeleton consists of large no. of ossicles
fused together known as the corona or shell
below the outer skin.
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With elongated body,cucumber or wormlike shape,without arms.
Usually without madreporite ,mouth and
anus lie at opposite ends of the body.
Muscular body wall with no spines and only
small ossicles.
Ambulacral grooves are covered,some of
the tube feet are modified into tentacles
around the mouth,some of them are with
suckers.
No pedicellaria
Ex. Holothuria sp. (Sea cucumber).
Sessile echinoderms attached by the
aboral surfaces.
 Oral surface directed to the upper side
containing mouth and anus.
 Tube feet with out suckers,ambulacral
grooves are open.
 No madreporite,no
spines,nopedicellaria.
 Ex.Heterometra sp.(Sea feathers)
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The body is compossed of small central disc
or calyx surrounded by 5 arms each
bifurcates twice,thus are formed of 20 arms
each fringed with double series of short
branches khnown as pinnules giving it the
feathery appearance.
 In each arm there is an open ambulacral
groove surrounded by tube feet help with
pinnules in pushing food particles to mouth.
 The aboral surface with appendages called
cirri by which the animal clings to the
ground.
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