Animal Diversity LOs

1. The two body forms of cnidarians are polyps (sessile, tubelike) and medusae (free-swimming, bell-like shape). Cnidarians live in aquatic environments.

2. Placozoans have no symmetry, no real shape, and the smallest amount of DNA ever measured in an animal.

3. Ctenophores (comb jellies) have radial symmetry, while cnidarians have biradial symmetry. Ctenophores are strictly marine and lack cnidocytes (stinging cells).

4. Two unique features of cnidarians are: 1) cnidarians have cnidocytes (stinging cells) and 2) cnidarians have colloblasts (sticky cells to capture prey).

5. The four major groups of lophotrochozoans are mollusks, bivalves, gastropods, and cephalopods. Mollusks are the most diverse lophotrochozoan group. They share a mantle and ecdysozoa-like cuticle exoskeleton.

6. The three main groups of mollusks are bivalves, gastropods, and cephalopods. They share a mantle, but differ in their body plans and appendages.

7. Key characteristics of Ecdysozoa include an exoskeleton that is shed (ecdysis), segmented bodies, and jointed appendages.

8. The three phyla of Ecdysozoa are nematodes, tardigrades, and arthropods.

9. Nematodes and tardigrades have cryptobiosis (dormancy), cuticle, and lack segments. Tardigrades have segmented bodies and clawed legs, and feed as predators/parasites.

10. Unique traits of arthropods include an inverted, hard exoskeleton, jointed appendages, and segmented bodies. They are very successful.

11. Examples: Chelicerates - horseshoe crabs, ticks, spiders; Myriapods - millipedes/centipedes; Crustaceans - crabs/lobsters; Insects - butterflies, bees, moths, flies.

12. Echinoderms are unique in having radial symmetry and a water vascular system as adults.

13. The five groups of echinoderms are: starfish, sea urchins, sea lilies, sea cucumbers, and sand dollars.

14. All chordates share a notochord, dorsal hollow nerve cord, and pharyngeal slits.

15. Cephalochordates retain chordate features as adults, while tunicates (sea squirts) lose these features.

16. All vertebrates share a vertebral column, cranium, endoskeleton, bilateral symmetry, and two pairs of appendages.

17. The paraphyletic group of "fish" includes the clades Sarcopterygii (lobe-finned fish), Actinopterygii (ray-finned fish), Agnatha (jawless fish), and Chondrichthyes (cartilaginous fish). They have diverse traits like jaws, fins, and skeletal types.

18. Amphibians are unique in having an aquatic larval stage and a terrestrial adult stage.

19. Amphibians and seedless vascular plants both require water/wet environments to reproduce.

20. A tetrapod is a four-limbed vertebrate.

21. An amniotic egg contains albumin (structure and water), egg yolk (provides energy), and other components to support embryonic development.

22. Birds are considered a subgroup of reptiles. All sauropsids (reptiles and birds) share scaly skin and other traits.

23. Dinosaurs are closely related to the extant group of birds.

24. Yes, mammals are amniotes.

25. Traits shared by all mammals include mammary glands, three middle ear bones, warm-blooded, hair/fur, and live birth.

26. The three major clades of mammals are: eutherians (placental mammals), marsupials, and monotremes. They differ in their methods of reproduction and development.

27. The most diverse groups of mammals are rodents and bats.

28. Insects are the most abundant animals.

29. Insects are the most species-rich group of animals.