1. Phylum Echinodermata The Spiny Skin Animals
Examples:
Sea Stars
Brittle Stars
Sea Urchins
Sea Cucumbers
Sea Lilies
Feather Stars

2. Pentamerous radial symmetry
Body is arranged around a central axis in 5 parts

3. Solaster

4. Water Vascular System
Unique organ system that water-filled tube and water pressure for both locomotion and feeding.
System of tubes end in tube feet.

5. Endoskeleton Consists of plates calcium carbonate (CaCO3).
Plates are often studded with spine, hence their name.
Typically divisible in 5 parts

6. Bottom Dwellers Benthic Most abundant on rocky shores
Can be found in every ocean, at all depths

7. Class Asteroidea: Sea Stars
Found from subtidal to deepest part of ocean
Five appendages (arms) radiating from a central axis
Eat mussels and are considered pests by seafood industry
Examples:
Bat Star (Pateria)- W. Coast, Kelp beds
Sun star (Solaster)- 10 –15 arms, eat other sea stars

8. Respiration
Skin Gills- ciliated finger-like projections on the dorsal surface of the skin
Breathe through their skin and tube feet
Coelom- fluid filled sac lined with cilia that beat and circulate water. Diffuse O2, CO2, and wastes

9. Feeding and Locomotion
Arms are used for locomotion and getting food.
Carried out by the Water Vascular System
Water enters the madreporite (sieve plate) stone canal Ring Canal Radial Canal Tube feet
Tube feet are delicate projections attached along the side of the radial canal in a groove

10. Feeding and Locomotion
Ampulla- top of the tube foot, resembles a medicine dropper.
Feet suction to surfaces. Allows sea stars to attach to bivalves and pull open shells by tugging for hours therefore
weakening the
adductor muscles.
Sea star pushes its
stomach out through
the mouth and digests
the food externally.

11. Response
Eyespots- tiny light receptors located at the end of each arm (orange in the picture). Light is converted into electrical impulses that are carried to central nerve ring around the mouth which then directs the arms.

12. Reproduction Sexually
Gonads are located inside each arm near the central disk.
Fertilization and development occur externally
In the picture are different phases of new organisms from single-celled organisms to larva.

13. Regeneration Sea stars can regenerate new arms if cut off
A new Sea Star can grow from an arm as long as part of the central disk is present.
In the photo a
Northern Sea Star is
regenerating two
arms. It will take
over a year!

14. Johnathan Bird Sea Stars

15. Class Echinoidea Sea Urchins and Sand Dollars
Oval or round bodies; lack arms; use spines and tube feet to move; eat algae off rocks using Aristotle’s Lantern (5-toothed mouth structure)

16. Aristotle’s lantern

17. Protection and Predation
Use spines to wedge themselves into spaces between rocks; protects from wave action and predators (except California Sea Otter!)

18. Reproduction Similar to sea star
Used for embryological studies because of blastula phase of urchin.

19. Sand Dollars and Sea Biscuits
Sand Dollar: short spines cover its skin; burrow in sand and feed on plankton.
Sea Biscuits: more rounded body; longer spines; lives around coral reefs.

20. Class Ophiuroidea Brittle Stars
Solitary, nocturnal creatures that hide under rocks during the day.
Found in intertidal zone to the deep; from tropics to Arctic
Use long muscles in long, skinny arms in order to scurry rapidly about on the sea floor.
Can detach appendages when attacked.
Brittle stars on a sea cucumber.

21. Class Crinoidea Sea lilies and Sea Feathers
Most ancient of echinoderms
Have feathery appendages to catch food (plankton)
Limited movement. Sea lilies are sessile; Sea feathers slowly crawl on coral reefs.

22. Class Holothuroidea Sea Cucumbers
Soft, oblong body w/no arms; tube feet arranged in five rows; no endoskeleton or spines; only have small bony pieces in the skin
Use sticky branching tentacles (enlarged tube feet) to trap microscopic organisms. Extend around mouth during feeding and retracted when disturbed.
No skin gills- take in and release water thru anus and gas exchange occurs in the coelom across membranes call the “respiratory tree”
If attacked, SC will release its digestive organs to leave a meal for the predator and escape.

23. Sea Cucumbers
examples