1. Phylum Echinodermata
“Spiny – skin”

2. 4 key characteristics Radially symmetrical Endoskeleton
Water Vascular System
Tube-feet

3. Key characteristics “Spiny – skin” No head or sign of cephalization
“Spines” protrude through skin
Calcium carbonate plates
Pedicellaria
No head or sign of cephalization
Oral vs Aboral surface

4. Development Radially symmetrical (Penta - 5 parts)
Except bilaterally symmetrical larvae
Bipinnaria
Deuterostomes
Blastopore develops into anus

5. Water – vascular system
Consists of
Tube feet
Ampullae (muscular sac)
Madreporite (sieve plate)

6. Water Vascular System Movement Madreporite Stone canal Ring canal
Radial canal
Ampullae
Muscle contraction
Water forced into tube feet

7. Biology of Echinoderms
Complete digestive tract and coelom
Feeding and Digestion
Cardiac stomach (invert into prey)
Pyloric stomach (digestive glands)
Nutrients transported by coelomic fluid

8. Biology of Echinoderms
Nervous system
Little known about nervous system
Reminiscent of nerve net
Nerve ring and radial nerve
Reproduction
Separate sexes
External fertilization
Regeneration

9. Other body systems
No circulatory, excretory, respiratory organ systems
Coelomic fluid bathes organs with nutrients and oxygen
Gas exchange and excretion of waste diffusion through the tube feet and skin gills

10. Types of Echinoderms Class Asteriodea (sea stars)
Class Ophiuroidea (brittle stars)
Class Echinoidea (sea urchins and sand dollars)
Class Holothuroidea (sea cucumbers)
Class Crinoidea (feather stars and sea lilies)

12. Class Crinoidea (feather stars and sea lilies)
Resemble ancestral echinoderms
Mucus covered feet, filter food
Sea lilies
Sessile and have stalk
Feather stars
Can swim or crawl as adults

13. Class Ophiuroidea Brittle stars and basket stars “Snake – like”
Long brittle arms for quick movement and filter water
Benthic (bottom dwellers)

14. Class Echinoidea Spine – like Sea urchins and sand dollars
Internal organs are enclosed in a test
Sea Urchins
Move tube feet, feed by scraping algae
Long spines
Sand dollars
Flat, round shape, shallow
Tube feet capture food as its passes over them

15. Class Echinoidea

16. Class Holothuroidea Sea Cucumbers Armless, benthic
Modified tube feet form tentacles around mouth

17. Class Asteroidea
Sea stars or starfish