1. Phylum Echinodermata
“spiny skinned”

2. 5 Classes Class Asteroidea Class Ophiuroidea Class Echinoidea
sea stars
Class Ophiuroidea
brittle stars
Class Echinoidea
sea urchins
Class Holothuroidea
sea cucumbers
Class Crinoidea
feather stars, sea lilies

3. What characteristics do you think they have in common?

4. Key Characteristics “spiny skin” Not always sharp, sometimes bumpy
White spotted sea cucumber
Pencil urchin
Stubborn sea cucumber

5. Key Characteristics pentamerous radial symmetry (based on five parts)
Multiples of five
Red Velvet Star
Most obvious in the sea star, but if you fold the arms of a sea star you will see the shape of a sea urchin, elongate that shape and you have a sea cucumber
Skeletons of sand dollar’s, clearly see 5 parts

6. Key Characteristics Calcareous endoskeleton (internal skeleton)
“test” = sea urchin’s skeleton
Sea urchin test showing bumps where spines attach

7. Key Characteristics water vascular system
network of water-filled canals
tube feet for attachment, locomotion, and stimuli

8. Tube Feet Sea star tube feet, sensing and moving in the environment
Sea cucumber tube feet modified to filter feed on detritus in the sand.
Sea urchin tube feet can catch drifting algae and forward it to the mouth on the underside of the body.

9. Additional Physical Characteristics
Complete Gut
Radial Nervous system (non-centralized)
Plump sea cucumber
Collector urchin
Spiny Brittle Star

10. Behavior Characteristics
Reproduction
Usually with separate sexes (spawning)
Ability to regenerate arms and asexual reproduction
Sea cucumber raised its head to spawn into the current.

11. Regeneration in a Sea Star

12. Feeding Behaviors Varies between groups Predators Herbivores
Scavengers
Filter Feeders
Sea cumbers filter feed or sift through detritus with tentacles.
Sea urchins graze on algae using their sharp teeth “Aristotle’s Lantern” located on their underside.

13. Sea Star Feeding
Sea stars are predators. Able to open shells with strong tube feet and can evert their stomach into the shell of another to liquify meat and then digest. (white is the stomach in a mussel).