Z250 - Lec33 Outline- ECHINODERMATA II (2017)

Zoology 250 (2017)

ECHINODERMATA (II): Skeleton, coeloms

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

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1) Unique porous 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; blood-vascular system (hemal system) is only rudimentary

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

ring canal

stone canal

madreporite

polian vesicles

radial canals

ambulacral grooves

lateral canals

podia

tube feet

ampullae

chemically

TRAIT Crinoid Asteroid Ophiuroid Echinoid Holothuroid

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

polian
vesicles N? Y Y Y* Y

ampullae
on podia N Y N Y Y

suckers
on podia N Y/N N Y/N Y/N

podia
penetration between
ossicles between
ossicles between
ossicles paired,
thru ossicles between
ossicles

podia
spacing stagger stagger paired stagger stagger

* Tideman's
body

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

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