Z250 - Lec33 Outline- ECHINODERMATA II (2004)

Zoology 250 (2004)

ECHINODERMATA (II): Skeleton, coeloms

(Echinoderm study images;
click on tree to see full cladogram)

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1) Unique calcareous, dermal ossicles give the phylum its name
2) Five coelomic systems are present: 2 major (perivisceral, water-vascular system) and 3 minor (hyponeural, perihemal, genital); all are isotonic with seawater, lined with cilia and likely aid circulation

3) The unique water-vascular system is a coelom lined with cilia

madreporite

polian vesicles

radial canals

lateral canals

tube feet

ampullae

TRAIT Crinoid Asteroid Ophiuroid Echinoid Holothuroid

madreporite multiple
pores aboral oral aboral internal
(to perivisc.)

polian
vesicles N? Y Y Y* Y

tube feet
suckers N Y/N N Y/N Y/N

podia
penetration between
plates between
plates between
plates paired,
thru plates between
plates

podia
spacing stagger stagger paired stagger stagger

ampullae
on podia N Y N Y Y

TRAIT	Crinoid	Asteroid	Ophiuroid	Echinoid	Holothuroid
madreporite	multiple pores	aboral	oral	aboral	internal (to perivisc.)
polian vesicles	N?	Y	Y	Y*	Y
tube feet suckers	N	Y/N	N	Y/N	Y/N
podia penetration	between plates	between plates	between plates	paired, thru plates	between plates
podia spacing	stagger	stagger	paired	stagger	stagger
ampullae on podia	N	Y	N	Y	Y

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