Guided Practice: Watch the movie Echinoderms Ultimate Animal 1. Why are echinoderms animals even though they have no brain? 2. Do echinoderms have heads or faces? 3. How many parts in the symmetry of sea star? 4. What happens when the arms of a sea star are joined together? 5. What happens when the urchin is turned on its side and has a good stretch? 6. Is an echinoderm'skeleton (like a sea star) similar or different than humans? 7. What is in the echinoderms bony platelets? 8. What holds the echinoderms in a certain shape together for hours? 9. What is the name of the living relay system that coordinates movement of arm? 10. What do sea urchins eat? 11. What do urchins use to help them find food? 12. Where does the urchin's food move to with help from its tube feet? 13. Why are sea cucumbers called vacuum cleaners of deep sea? 14. What animal makes up vast majority of animals on ocean floor? 15. Why do its tube feet shovel sand into the sea cucumber's mouth? 16. How many brittle stars are on the ocean floor? 17. How are brittle stars patient predators? 18. What type of system controls the tube feet? 19. What is the name of the plate where water is inflated? 20. What is the name of the round muscles that are in the five arms? 21. What part of the echinoderm body helps them detect food? 24. What is at the end of feet that helps sense light and darkness? 25. How do sea stars attack mussels on a wharf? 26. What part of the sea star's body moves into body of prey? 27. What do sea stars puts into mussel to digest it? 28. What is the name of the giant sea star with up to 20 arms?

Let's review the *Echinoderms: Ultimate Animal* movie and answer your questions.<br /><br />1. **Why are echinoderms animals even though they have no brain?** Echinoderms are considered animals because they are multicellular, heterotrophic (they consume other organisms for energy), and capable of movement at some stage in their life cycle. While they lack a centralized brain, they have a nerve net that coordinates their movements and responses to stimuli.<br /><br />2. **Do echinoderms have heads or faces?** No, echinoderms do not have distinct heads or faces. They exhibit radial symmetry, meaning their body parts are arranged around a central axis.<br /><br />3. **How many parts in the symmetry of a sea star?** Sea stars typically have five-part radial symmetry (pentaradial).<br /><br />4. **What happens when the arms of a sea star are joined together?** This question is a bit ambiguous. If you mean naturally, the arms are normally joined at the central disc. If you mean experimentally, joining them might restrict movement and feeding.<br /><br />5. **What happens when the urchin is turned on its side and has a good stretch?** An urchin will use its tube feet and spines to right itself.<br /><br />6. **Is an echinoderm's skeleton (like a sea star) similar or different than humans?** Very different. Humans have internal skeletons made of bone. Echinoderms have an internal skeleton called an endoskeleton, but it's made of calcium carbonate plates called ossicles, often covered by a thin skin.<br /><br />7. **What is in the echinoderms bony platelets?** The bony platelets, or ossicles, are made of calcium carbonate.<br /><br />8. **What holds the echinoderms in a certain shape together for hours?** A specialized connective tissue called mutable collagenous tissue (MCT) allows echinoderms to maintain rigid postures without expending much energy.<br /><br />9. **What is the name of the living relay system that coordinates movement of arm?** The nerve net coordinates movement, though it's not a "relay system" in the same way as a vertebrate nervous system.<br /><br />10. **What do sea urchins eat?** Sea urchins are primarily herbivores, feeding on algae and kelp. Some are also opportunistic scavengers.<br /><br />11. **What do urchins use to help them find food?** They use their tube feet and spines for locomotion and sensing their environment, and some have specialized sensory cells that can detect chemicals in the water.<br /><br />12. **Where does the urchin's food move to with help from its tube feet?** The tube feet move food towards the mouth, which is located on the underside of the urchin.<br /><br />13. **Why are sea cucumbers called vacuum cleaners of deep sea?** Sea cucumbers are deposit feeders, meaning they ingest sediment and extract organic matter. This feeding action cleans the seafloor.<br /><br />14. **What animal makes up vast majority of animals on ocean floor?** This is a broad question and depends on the specific location and depth. However, in many deep-sea environments, echinoderms (including sea cucumbers, brittle stars, and sea stars) are very abundant.<br /><br />15. **Why do its tube feet shovel sand into the sea cucumber's mouth?** The tube feet around the mouth are modified for feeding and help gather and move sand and sediment containing organic matter into the mouth.<br /><br />16. **How many brittle stars are on the ocean floor?** There are thousands of brittle star species, and their populations can be incredibly dense in some areas of the ocean floor. A precise number is impossible.<br /><br />17. **How are brittle stars patient predators?** Brittle stars can be both predators and scavengers. They are considered patient predators because they can lie in wait, using their camouflage and sensitive arms to detect and capture prey.<br /><br />18. **What type of system controls the tube feet?** The water vascular system, a network of fluid-filled canals, controls the movement of the tube feet.<br /><br />19. **What is the name of the plate where water is inflated?** The madreporite is the plate where water enters the water vascular system.<br /><br />20. **What is the name of the round muscles that are in the five arms?** The muscles within the arms are not typically referred to by a single specific name. They are often described as longitudinal and circular muscles that work together to facilitate arm movement.<br /><br />21. **What part of the echinoderm body helps them detect food?** Tube feet, sensory cells on their skin, and sometimes specialized structures near the mouth help them detect food.<br /><br />24. **What is at the end of feet that helps sense light and darkness?** Some echinoderms have simple eyespots at the tips of their tube feet that can detect light and dark.<br /><br />25. **How do sea stars attack mussels on a wharf?** Sea stars use their tube feet to pry open the shells of mussels.<br /><br />26. **What part of the sea star's body moves into body of prey?** The sea star everts its stomach, extending it out of its mouth and into the prey's shell.<br /><br />27. **What do sea stars put into mussel to digest it?** They release digestive enzymes into the mussel to break down its tissues.<br /><br />28. **What is the name of the giant sea star with up to 20 arms?** The sunflower sea star (*Pycnopodia helianthoides*) can have up to 24 arms. There are other multi-armed sea stars as well, like the crown-of-thorns starfish (*Acanthaster planci*).<br />