Worksheet:

Sea Urchin Anatomy

The feeding structure on a sea urchin is called Aristotle’s Lantern, due to its unusual shape. Using the materials below (and following the drawing guidelines we presented earlier this semester), do a sketch of Aristotle’s lantern, labeling as many structures as you can. Scan and insert your sketch into the worksheet.

Sea Star Anatomy

View the two videos below – one showing the external anatomy of a sea star, and the other a dissection of the internal structures. Use the information to label the worksheets below.

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1. Coelom—the space containing the internal organs/viscera
2. Stomach—5-­‐lobed, sac-­‐like structure dorsal to the mouth in central disc region, connects to caeca
3. Digestive glands—pair in each arm connect to stomach. Also known as hepatic caeca.
4. Gonads—found under the caeca in each arm. Testes or ovaries (sexes separate in echinoderms)
5. Water vascular system: includes
   1. Stone canal: connects madreporite to ring canal
   1. Ring canal: hard, circular tube-­‐like structure, around mouth
   1. Tiedemann bodies: swellings (9) along ring canal
   1. Radial canal: from ring canal down each arm, connects water vascular system to ampullae
   1. Ampullae: spherical “bulbs” connect to tube feet

SHAPE OF LIFE: ECHINODERMS

Watch the video at the link below, and answer the questions in your worksheet.

https://video.lanecc.edu/media/The+Shape+of+Life+Vol.+7+-+Ultimate+Animal/0_ad0xz0ze/84523512

• What allows seastars to hold their position effortlessly for hours?
• How fast can an urchin eat seaweed?
• How do soft-­‐bodied sea cucumbers defend themselves from predators?
• What do brittle stars eat?
• Can seastars see?      
• If yes: Can they see light?      
• Can they form an image?
• Describe how a seastar eats a bivalve.