1. In what phylum are starfish found? • Echinodermata (echinoderms) -sea urchins -sand dollars -sea cucumbers
2. What is the habitat for starfish? • Sea stars live in the sea from the shore to the deepest ocean. They live in sea grass beds, under rock rubble, on coral reefs and rocky underwater cliffs, and in sand and mud.
3. On what do starfish feed? • Sea stars are carnivores (meat-eaters). They eat clams, oysters, mussels, coral, fish, and other animals. They push their stomach out through their mouth (located on the underside of the sea star) and digest the prey.
4. What structure in their body helps them catch their food? • Many echinoderms have suckers on the ends of their feet that are used to capture and hold prey, and to hold onto rocks in a swift current.
5. What does echinoderm mean in Greek? Why is this a good name for this group? • Spiny skin • (You answer the 2nd question yourself.)
6. Name 2 classes of echinoderms & a member of each class. Classes: Asteroidea - sea stars Ophiuroidea - brittle star Echinoidea - sea urchins Crinoidea - feather stars Holothuroidea - sea cucumbers
7. Where does water enter a sea star? Where does it leave? In starfish, water enters the system through a sieve-like structure on the upper surface of the animal, called the madreporite. This overlyies a small sac, or ampulla connected to a duct termed the stone canal, which is, as its name implies, commonly lined with calcareous material. The stone canal runs to a circular ring canal, from which radial canals run outwards along the ambulacral grooves which extends from the mouth to the end of each ray on its oral/under side. Opposite the ambulacral groove is an ambulacral ridge on the aboral side of each ray. (Exits through the tubefeet.)
1. Madreporite 2. Stone Canal 3. Ring Canal 4. Radial Canal 5. Ambulacral Groove
The tiny pedicellaria of a sea star looks like a claw when viewed under a microscope. It can remove unwanted particles from the seastar's body. If food happens to land on the sea stars aboral side, it can also use these pedicellaria to transport the food to the arms and then into its mouth.
The sea star has two stomachs, the pyloric and the cardiac. The cardiac stomach can be inverted to the outside of the sea star thus enabling it to get into small openings. The other stomach, the pyloric, can produce digestive enzymes and store digested food.
Answers to previous slide: A . AboralB. Oral 1. Anus 2. Madreporite 3. Arm/ray4. Central disc 5. spines 6. Oral spines 7. Eyespot8. ambulacral groove 9. tube feet 10. Mouth