Answers to Invertebrates Exercises

Let’s see how you did! If you didn’t get a few of these, don’t let it stress you out – it just means you need to play with more experiments in this area. We’re all works in progress, and we have our entire lifetime to puzzle together the mysteries of the universe!

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Answers:
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1. What is the difference between invertebrates and vertebrates? Vertebrates are animals with backbones while invertebrates do not have a backbone.
2. Are sponges colonies of cells? If so, are all the cells the same type? Yes, sponges are colonies of cells. No, they are not all the same type—they are specialized to perform different functions such as filter food, and attach the sponge to the ocean bottom.
3. What are sessile filter feeders? Organisms, such as sponges, which filter their food out of the water, and are attached to the substrate beneath them—they do not move.
4. Would you want to touch an organism with nematocysts? Why or why not? No way! Nematocysts are the stinging cells found on Cnidarians!
5. What is the difference between a polyp and a medusa? A polyp has an upward facing mouth while medusa’s mouths face downward.
6. What are two differences between sponges and Cnidarians? Cnidarians have real tissue, and have a body cavity.
7. Name two examples of Cnidarian colonies. Coral reefs and Portuguese Men-O-War.
8. What are some of the differences between flatworms, roundworms, and segmented worms? Flatworms have neither a body cavity nor segments. Roundworms only have a body cavity, and segmented worms have both a body cavity and segments.
9. What is an incomplete digestive system? It is a digestive system with only one opening—a mouth.
10. Which part of a segmented worm serves as its hydroskeleton? Its body cavity.
11. Which invertebrate has a radula, and what is it used for? Mollusks have radula, and it is used for feeding.
12. Do Echinoderms have exoskeletons? No, they have endoskeletons.
13. Give two examples of Echinoderms. Starfish, sea urchin, sea cucumber, etc.
14. What role doe nerve nets play in Echinoderms? They act as a type of brain—receiving and processing information.
15. Which phylum molts its exoskeleton in order to grow? Arthropoda.
16. What are three examples of arthropods? Crabs, lobsters, scorpions, spiders, mites, ticks, etc.
17. Do arthropods only use book lungs to breath? No, aquatic arthropods use gills and some terrestrial arthropods use tracheal systems.
18. What are the two major groups of insects? Winged insects, and wingless insects.
19. How do insects breathe? Through structures called spirials.
20. How do most insects reproduce? Through sexual reproduction that results in eggs (oviparous).

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