1. Invertebrate Animals CHAPTER 17 What is an Animal? Early Animals Significant Invertebrate Animal Features Invertebrate Groups (Phyla) Sponges (Phylum Porifera) Cnidarians (Phylum Cnidaria) Flatworms (Phylum Platyhelminthes) Roundworms (Phylum Nematoda) Segmented Worms (Phylum Annelida) Arthropods (Phylum Arthropoda) Molluscs (Phylum Mollusca) Echinoderms (Phylum Echinodermata)

2. What Is an Animal? Animals –Eukaryotic, multicellular, heterotrophic organisms that obtain nutrients by ingestion –Mostly reproduce sexually and then proceed through a series of developmental stages –Usually have muscle cells, as well as nerve cells that control the muscles –Have distinct specialized cells (tissues) –Digest their food within their bodies

3. Figure 17.3 Life Cycle of An Animal Dominant diploid stage

4. Early Animals and the Cambrian Explosion Animals probably evolved from a colonial flagellated protist that lived in Precambrian seas At the beginning of the Cambrian period, 542 million years ago, animals underwent a rapid diversification.

5. Survey of Organisms Grid

6. The development of true tissues –Specialized cells living in sheets or masses within an organism Major Evolutionary Novelties in the Evolution of Invertebrate Animals The development of radial or bilateral symmetry The development of a true body cavity (coelom) –A fluid-filled, muscle-lined space separating the digestive tract from the outer body wall. The development of segmentation –Body is subdivided into separate parts which can then develop specialized functions The development of a complete gut –Incomplete digestive tracts have a mouth but no anus

7. Figure 17.7 Types of Body Symmetry Seen in Animals

8. Major Invertebrate Phyla Invertebrates –Are animals without backbones. –Represent 95% of the animal kingdom –Each invertebrate group we will study is in a different phylum: Domain Eukarya –Kingdom Animalia w Phylum X

9. Invertebrate Animals CHAPTER 17 What is an Animal? Early Animals Significant Invertebrate Animal Features Invertebrate Groups (Phyla) Sponges (Phylum Porifera) Cnidarians (Phylum Cnidaria) Flatworms (Phylum Platyhelminthes) Roundworms (Phylum Nematoda) Segmented Worms (Phylum Annelida) Arthropods (Phylum Arthropoda) Molluscs (Phylum Mollusca) Echinoderms (Phylum Echinodermata)

10. Figure 17.6 Evolutionary Tree of Kingdom Animalia

11. Sponges (Phylum Porifera) Includes sessile (non-motile) animals Lacks true tissues Is asymmetrical in body shape –Porous, bulbous mass with hollow interior and exit hole at the top Composed of only three cell types, the most important are collar cells (choanocytes) –Flagella drive water current inward to hollow space and out osculum –Food particles are trapped on sticky collars and passed to other cells Some sponges produce spicules (skeletal rods) of silica to help support shape

12. Figure 17.6 Evolutionary Tree of Kingdom Animalia

13. Cnidarians/Stinging Cell Animals (Phylum Cnidaria) True body tissues Body shape in floating medusa or anchored polyp form Radial symmetry Tentacles with stinging cells (cnidocytes) Food items brought into gastrovascular cavity where they are digested by enzymes

14. Figure 17.11 Cnidarian Body Shape is Either a Polyp or a Medusa

15. Examples of cnidarians –sea anemones, jellies, and coral animals. Hydra Budding Hydra Eating Daphnia Hydra Releasing Sperm Jelly Swimming Thimble Jellies Coral Reef

16. Figure 17.6 Evolutionary Tree of Kingdom Animalia

17. Flatworms (Phylum Platyheminthes) Bilateral symmetry Flattened body plan Cephalization of the nervous system: simple brain No body cavity (coelom) Incomplete gut with enhanced absorptive area Many are parasitic: they derive their nutrition by living on the flesh or juices of another animal

18. Figure 17.15 Examples of Some Flatworms That Cause Disease Tapeworm Life Cycle Blood fluke Life Cycle

19. Figure 17.6 Evolutionary Tree of Kingdom Animalia

20. Figure 17.8 Three Conditions of the Body Cavity (Coelom) Within Animals

21. Roundworms (Phylum Nematoda) Round in cross- section Bilateral symmetry Complete gut Pseudocoelom (false body cavity) About 30% are parasitic Individuals are either male or female Occur in aquatic and moist terrestrial habitats.

22. Figure 17.16 Caenorhabtidis elegans Crawling Examples of Roundworms Life cycle of Trichinella spiralis

23. Figure 17.6 Evolutionary Tree of Kingdom Animalia

24. Segmented Worms (Phylum Annelida) Bilateral symmetry Round in cross-section Segmented True body cavity (coelom) Primitive circulatory system with “pumping” vessel elements Complete gut Includes earthworms, leeches, tube worms on dock pilings and ribbon worms in the sediment (polychaetes)

25. Figure 17.18a Examples of Segmented Worms (Annelids) Polychaetes in "A variety of marine worms": plate from Das Meer by M. J. Schleiden (1804–1881). Deposit and Filter Feeders Leeches: fluid feeders Earthworms are deposit feeders Tubeworms

26. Figure 17.6 Evolutionary Tree of Kingdom Animalia

27. Jointed-Footed Animals (Phylum Arthropoda) Jointed appendages Exoskeleton of chitin Segmented into 3 specialized body parts: head, thorax, and abdomen Bilaterally symmetrical True coelom Sophisticated sensory appendages (antenna, hairs, feelers, eyes) Some with elaborate social behavior (e.g. hives and colonies) Some (insects) undergo metamorphosis or body restructuring Most “successful” (diverse) of all animal groups Lobster Mouth Parts

28. Arthropod Diversity: Four Main Groups Arachnids –Spiders, scorpions, ticks, and mites

29. Crustaceans –Crabs, lobsters, crayfish, shrimps, barnacles, and pill bugs Arthropod Diversity: Four Main Groups Pill bugs (isopods)

30. Millipedes and Centipedes Arthropod Diversity: Four Main Groups

31. Insects (many Orders) Arthropod Diversity: Four Main Groups Dragonflies Grasshoppers/Crickets True Bugs Beetles Aphids/Cicadas Butterflies Flies Bees/Wasps

32. Figure 17.25 Butterfly Emerging Metamorphosis: Body Restructuring From Juvenile to Adult

33. Figure 17.6 Evolutionary Tree of Kingdom Animalia

34. Molluscs (Phylum Mollusca) Soft-bodied animals with viscera, a mantle, and a foot Most molluscs have shells or shell remnants Rasping tongue (radula) used in grazing Bilateral symmetry, true coelom Includes snails, slugs, clams, octopuses, and squids, to name a few.

35. Nudibranchs Three Major Classes of Molluscs

36. Figure 17.6 Evolutionary Tree of Kingdom Animalia

37. Spiny-Skinned Animals (Phylum Echinodermata) Spiny skin Not segmented Five-part radial symmetry Water pressure-based (hydrostatic) endoskeleton Tube feet for motility Exclusively marine Includes sea stars, sand dollars, sea urchins, and sea cucumbers. Echinoderm Tube Feet

38. Figure 17.28 Types of Echinoderms

39. Invertebrate Animals CHAPTER 17 What is an Animal? Early Animals Significant Invertebrate Animal Features Invertebrate Groups (Phyla) Sponges (Phylum Porifera) Cnidarians (Phylum Cnidaria) Flatworms (Phylum Platyhelminthes) Roundworms (Phylum Nematoda) Segmented Worms (Phylum Annelida) Arthropods (Phylum Arthropoda) Molluscs (Phylum Mollusca) Echinoderms (Phylum Echinodermata)