1. Phylum Echinodermata: Echinoderms
“Spiny Skins”

2. Do we have organisms from the Phylum Echinodermata in our tanks?

3. Echinoderms Main Characteristics
There are more than 5000 species of Echinoderms
They have exoskeletons and they are musculoskeletal
They have penta-radial symmetry.
They have tube feet
They have water vascular systems
They are benthic organisms

4. Types of Echinoderms

5. How many classes do you think Phylum Echinodermata has?

6. 5 Classes of Echinodermata
Asteroidea
Ophiuroidea
Echinoidea
Holothuroidea
Crinoidea
Which Class do you think contains sea stars (Hint: Look at the Prefixes)?
Do you think brittle stars are in the same class as sea stars?

7. Class Asteroidea (Sea Stars)
Aster means “Star”, Oides means “In the form of”
Large Body Cavity (Coelom)
Has a defined Circulatory System
Sea Stars are able to regenerate
Has a Respiratory System
Is this the first Phylum with a defined respiratory system?

9. Sea Star Anatomy

10. Ophiuroidea (Brittle Stars)
Similar to Sea Stars, have regenerative capability
Arms are not attached to arms
They are not active predators, instead they eat plankton
Have greater arm flexibility due to length
Bioluminescent (produce light in the green wavelengths)
Why do you think Brittle Stars have this capability?
Do not depend on tube feet for locomotion

11. Echinoidea (Sea Urchins)
Same structure as Sea Stars, penta-radial symmetry
Longer spines than Sea Stars
Move by means of tube feet similar to Sea Stars
They are herbivores (feed on algae/marine plants)
They eat using a structure called Aristotle's Lantern to scrape their food
Ecologically they play the role of control algae population size
They are typically found attached to rocks on ocean floor
Over the years they increased in popularity as an food item for human consumption.
Has anyone ever eaten a Sea Urchin?

13. Sea Urchin Anatomy

14. Echinoidea (Sand Dollars)
Are found on the sandy shore or muddy bottoms.
They feed standing on edge with their tube feet acting as filters.
The star pattern seen on top of the sand dollars is actually caused by special breathing tube feet!
The mouth is found on the under side of the animal.
Similar structurally to Sea Urchins

16. Sand Dollar Anatomy

17. Holothuridea (Sea Cucumbers)
Have a different Elongated body plan, however they still have radial symmetry
Similar to other classes, they use tube feet to move
They have separate sexes (Male sea cucumber/female sea cucumber)
They play an ecological role of filtering organic nutrients out of the sand via their oral tentacles
Economically they are again used for human consumption, especially in Asian cultures
They have two built-in defense mechanisms
They use tubules called cuvierian tubules which are sticky and poisonous
They have the ability to expel their internal organs

19. Sea Cucumber Anatomy

20. Crinoidea (Sea Lilies)
Krinon, prefix Crino means “Lily”
They have radial symmetry
Similar in structure and organ systems to the other classes
They move using their tube feet
Again they have separate males and females
They have light feather-like arms
They feed on small sea water particles via their limbs which are free flowing in the water.