Chapter 23 Invertebrate Diversity. 23.6 Echinoderms A. What are echinoderms? spiny-skinned animals...

Chapter 23

Invertebrate Diversity

23.6 Echinoderms

A. What are echinoderms? spiny-skinned animals with five-

part radial symmetry, an internal skeleton, a water vascular system, and suction cup-like structures called tube feet

live in the ocean

23.6 Echinoderms

B. Body Plan of Echinoderms 1. five symmetrical parts organized

around a center 2. water vascular system:

internal network of fluid-filled canals

a. madreporite: connects system to the outside

23.6 Echinoderms

B. Body Plan of Echinodermsb. ring canal: circles the digestive system in center

c. radial canals: extend into each body segment

d. tube feet: attached to radial canals; act like suction cups

Echinoderm anatomy

23.6 Echinoderms

C. Form & Function 1. Feeding: use tube feet to pry

open bivalve mollusks; some eat algae; others eat detritus

2. Respiration: occurs through tube feet

3. Internal Transport: digestive glands and body fluids

23.6 Echinoderms

C. Form & Function 4. Excretion: tube feet 5. Response

a. no head; primitive nervous systemb. eyespots sense light or darkc. Protection: hiding; spines ineffective defense

6. Movement: tube feet and muscles

Tube Feet

23.6 Echinoderms

C. Form & Function 7. Reproduction

a. sexual; separate sexes or hermaphrodites

b. asexual; regeneration abilities

Regeneration

Regeneration

Brittle Star

Sea Urchin

Sea Urchin Skeleton

Sand Dollar and Sand Dollar Skeleton

Sea cucumber

Sea cucumber

Feather star

Feather star

Crinoid