Phylum: Echinodermata

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Zoology Chapter 16

Phylum: Echinodermata

Echinos = Spiny

Derma = Skin

Ata= to bear

“bears spiny skin”

Phylum Echinodermata

5 Classes

Class Crinoidea

Sea lilies

Feather stars

Class Asteroidea

Sea Stars

Class Ophiuroidea

Brittle Stars

Class Echinoidea

Sea Urchins (venomous)

Sand Dollars

Class Holothuroidea

Sea cucumbers

Characteristics

Calcareous endoskeleton

Ossicles- “small bones”

Adults with pentaradial symmetry (5 points)

Larvae with bilateral symmetry

Water-vascular system

Water-vascular system

Composed of water-filled canals

Used in

Attachment

Feeding

Locomotion

Respiration

Circulation of nutrients and wastes

Extends to each arm and tube feet

Tube feet act as suction cups

Contract & expand

Digestion

Complete digestive tract

Eat clams

Tube feet open shell

Stomach forced through mouth

Stomach into opening between clam’s shells

Digestive enzymes break down tissue

Sea Star sucks out predigested food

Eat algae

Nervous System

Nerve Net

Nerve Ring

Radial Nerves

Eyespots

Sea stars on each arm

Regeneration & Reproduction

Reproduction

Mostly dioecious; but no sexes

Sexual & Asexual

2 Gonads are present in each arms

Regeneration

Broken arms

New body from broken arm

Pearl Diver Story

A form of Asexual Reproduction

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