1. Bellwork: 11/19/2013
Many students seemed to mix up Porifera & Cnidaria
Make sure to avoid that on the next unit since it includes:
Echinoderms
Bivalves
Cephalopods
Gastropods
Mollusks
Crustaceans

2. Echinoderms

3. Phylum Echindermata Share common features with chordates
Radial Symmetry
Usually slow moving or sessile
Possess a thick calcium plate endoskeleton surrounded by a thin skin layer
Possess a unique Water Vascular System, which continues throughout animal and extends into extensions called Tube Feet.
- Functions for locomotion, feeding, & gas exchange.

4. Water vascular system
A separate coelom is used with interconnecting fluid filled tubes and canals
A ring canal circles the mouth and gives off 5 radial canals
The radial canal is exposed and runs along the ambulacral groove
Phylum Echinodermata

5. Water Vascular System
Phylum Echinodermata

6. Tube Feet The ampullae is a small ball that sits above the tube foot
Contraction and expansion of the ampulla accomplishes movement
Phylum Echinodermata

7. Sea Stars
Usually have 5 (or multiple of 5) arms radiating from central disk
Tube feet located underneath each arm used for locomotion & grasping prey. Operate by hydraulic principles.

8. Echinoderms Skeleton
Have an internal skeleton of calcium carbonate
Ossicles vary in size and structure and are manufactured by specialized cells
Phylum Echinodermata

9. Anatomy of a Sea Star
B: Ambulacral
Groove
F: Arm E C A

10. Fig. 22.2b

11. Feeding
Feed on mollusks by pulling shells apart and extending stomach outside the mouth into the bivalve. The bivalve is digested within it's shell. The sea star than re-ingests its stomach

12. Reproduction Can reproduce sexually by releasing sperm and egg.
They are NOT hemaphrodites
Can reproduce by regeneration

13. Regeneration
Many species autotomize, leaving predators with a nutritious souvenir while they escape
Most spp. can regenerate from fragments that include the disk
Phylum Echinodermata

14. Sea Stars

15. Brittle Stars Distinct central disks with long tube-like arms
Lack suckers
Move by serpentine motion of their arms

16. Brittle Stars vs Sea Star Movement
Sea Stars use their tube feet to crawl across the sea floor
Brittle Stars use one of their legs as a lead and pull themselves across the sea floor
Sea star locomotion
Brittle Star Locomotion

17. Brittle Star

18. Sea urchins & sand dollars
Lack arms, but possess tube feet
Many species of urchins possess poisonous spines used for defense

19. Sand Dollar
Sea Urchin

20. Sea Cucumbers Soft body with reduced structure Tentacles near mouth
Respiratory tree

21. Sea Cucumbers Are elongated along oral-anal axis
Lack spines and have reduced endoskeleton.
Do possess tube feet and water vascular system
Expels its insides as a defense mechanism

22. Sea Cucumber

23. Echinoderm Lab: Groups of 4 or less

24. Station #1 – Sand-Sifting Sea Star
Flip the sea star onto its dorsal side & observe:
Draw or describe how the sea star flips itself back over.
What sensory cells are involved in keeping the sea star upright?
Place the sea star upside down the dissection microscope.

25. Station #1 – Sand-Sifting Sea Star
3) Observe, sketch, and label the following regions: center of the sea star, middle of an arm, terminal end of the arm.
Label if present in each sketch:
Mouth
Tube feet
Abulacral groove
Spines
Sensory Tentacles

26. Station #2 – Tube Feet Prepared Slide
Observe & sketch the prepared slide on both the low & medium objectives.
Describe the shape/texture of the ectoderm on the tube feet.
Why are the tube feet hollow?
What is the name of the tissue that the tube feet are connected to?
Why does this tissue appear to have empty pockets.
Aside from locomotion & feeding, what other job do tube feet perform? What feature of the tube feet allows this to be possible?

27. Station #3 – Amputated Arm & Cross-section
Examine the cross-section under the dissection microscope.
Sketch the cross-section
Label the following:
Digestive gland/pore
Ambulacral groove
Tube feet
Ampulla
Water vascular pore

28. Station #4 – Brittle/Serpent Sea Star
Remove the brittle star/serpent sea star from the container & place it on the table.
How does it move?
How does a sea star move in comparison?
What are the advantages & disadvantages of both types of movement?
Observe & sketch the central disk of the brittle/serpent sea star.

29. Station #4 – Brittle/Serpent Sea Star
3. Observe & sketch the amputated brittle sea star leg under the dissection microscope & the cross-section under the standard microscope.
How is this arm different than the arms of a standard sea star?

30. Station #5 – Sea Urchin
Using your finger, gently poke one of the spines on the sea urchin.
What is its response?
What receptors are involved in this detection?
Using the urchin with shorter spines, gently flip the urchin over.
How does it flip itself over?
Is this a faster or slower process than with the sea star?
Why do sea urchins have tube feet that are much longer than those found on any other echinoderm?

31. Station #5 – Sea Urchin Observe the long-spined urchin.
What are the white spots on the dorsal portion of the animal?
What is the green (orange?, red?, sorry…I’m not sure what color it is) anatomical feature found in the very center of the dorsal side?

32. Station #6 – Sea Cucumber
Observe & sketch the sea cucumber under the dissection microscope.
Label the tube feet, respiratory tree, and tentacles.
Describe the texture of this animal in comparison to the other echinoderms.
While considering the relatively low number of tube feet found on this organism in comparison to other echinoderms, what functions would the sea cucumber lack & what additional anatomical feature(s) can be found to address these deficiencies?