Dissection in biology provides a hands-on education above and beyond reading a textbook. By seeing, touching and exploring different organs, muscles and tissues inside an animal and seeing how they work together allows you to really understand your own body and appreciate the amazing world around us. And it’s not hard – you can dissect a starfish right at home using an inexpensive specimen with a dissection guide and simple dissection tools! Many doctors, surgeons and veterinarians report that their first fascination with the body started with a biology dissection class.

In today’s dissection, we’ll be looking at a starfish. Starfish are members of the phylum Echinoderm. There are many things that make starfish interesting: their rays are symmetrical around their center (this is called radial symmetry), they use seawater instead of blood to transport nutrients through their bodies (this is called a water vascular system), and they move around using tube feet on the underside of their bodies.

Materials

• Starfish (click if you need the whole kit, or just the starfish)
• Dissection tools
• Dissection guide

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Procedure

1. Observe the external anatomy of your starfish. See if you can locate the following:
   1. Madreporite (sieve plate)
   2. The spiny skin on the top side of the starfish
   3. Tube feet
   4. Ambulacral grooves
   5. Mouth
2. Remove a large piece of skin from one of the starfish’s rays
   1. Using your scissors, snip off a small piece of the tip of one ray
      1. Choose a ray that does not attach near the madreporite
   2. Take the point of the scissors, place it into the opening you created in step 2.1.1 above, and carefully cut up the length of the ray, around the center of the starfish, and back down the length of the ray
      1. Make your cut parallel to the table
      2. Do not cut around the madreporite, rather keep your cut to the inside of the madreporite
3. Look for the following organs:
   1. Digestive glands
   2. Pyloric stomach and pyloric ducts
   3. Cardiac stomach
   4. Gonads (ovaries or testes)
4. Identify the parts of the water vascular system:
   1. Madreporite
   2. Stone canal
   3. Ring canal
   4. Radial canal
   5. Ampullae
   6. Tube feet

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Click here to go to part:21 Dissecting a Crayfish