1. Albia Dugger Miami Dade College Cecie Starr Christine Evers Lisa Starr www.cengage.com/biology/starr Chapter 24 Animals II: The Chordates (Sections 24.1 - 24.3)

2. 24.1 Windows on the Past Fossils are physical evidence of changes that led to modern animal diversity Radiometric dating assigns fossils to places in time Structure, biochemistry, and genetic makeup of living organisms provide information about branchings

3. Transition Fossils Fossils reveal that birds evolved from feathered dinosaurs, and that some early birds had a bony tail and teeth

4. 24.2 The Chordate Heritage Chordates are distinguished by their embryonic traits Chordates include vertebrates and two lineages of marine invertebrates chordate Animal with an embryo that has a notochord, dorsal nerve cord, pharyngeal gill slits, and a tail that extends beyond the anus

5. Chordate Characteristics Four features define chordate embryos: a notochord a dorsal hollow nerve cord a pharynx with gill slits a muscular tail extending past the anus These features may or may not persist in adults

6. Key Terms notochord A rod of stiff but flexible connective tissue that runs the length of the body in chordate larvae or embryos and supports it

7. Invertebrate Chordates Invertebrate chordates include lancelets and tunicates lancelet Invertebrate chordate that has a fishlike shape and retains the defining chordate traits into adulthood tunicate Invertebrate chordate that loses its defining chordate traits during the transition to adulthood

8. Lancelets Gill slits filter food particles out of the water and also function in gas exchange

9. Fig 24.1a, p. 378 Lancelets

10. Fig 24.1a, p. 378 anus tail extends past anus eyespot notochord dorsal nerve cord pharynx with gill slits Lancelets

11. Fig 24.1b, p. 378 Lancelets

12. ANIMATION: Lancelet body plan To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERECLICK HERE

13. Tunicates Larvae swim about briefly, then undergo metamorphosis Adults retain only the pharynx with gill slits Adults feed by drawing water in through an oral opening, past gill slits, then expels it through a second opening

14. Larval and Adult Tunicates.

15. Fig 24.2, p. 378 pharynx with gill slits A C 1 cm Larval and Adult Tunicates

16. Fig 24.2a, p. 378 Larval and Adult Tunicates

17. Fig 24.2c, p. 378 Larval and Adult Tunicates

18. ANIMATION: Tunicate body plan To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERECLICK HERE

19. Overview of Chordate Evolution Craniates are chordates with a braincase of cartilage or bone Most craniates are vertebrates craniate Chordate with a braincase vertebrate Animal with a backbone

20. Chordate Evolution (cont.) Vertebrae and other skeletal elements are components of the vertebrate endoskeleton Jaws evolved from bony parts that supported gill slits of early jawless fishes endoskeleton Internal skeleton made up of hardened components such as bones

21. Chordate Evolution (cont.) Evolutionary modifications allowed animals to move from water onto land: Fins would evolved into limbs of tetrapods A subset of tetrapods, amniotes produce eggs that allow embryos to develop away from water

22. Key Terms tetrapod Vertebrate with four legs, or a descendant thereof amniote Vertebrate in which the embryo develops surrounded by fluid enclosed by membranes inside the egg

23. Evolutionary Tree of Vertebrates

24. Fig 24.3, p. 379 Vertebrates Craniates Chordates Tetrapods Amniotes ancestral chordate Bony appendages Amniote eggs Swim bladder or lung(s) Backbone Tunicates Reptiles (with birds) Lancelets Jaws Four limbs Cartilaginous fishes HagfishesLampreys Ray-finned fishes Lobe- finned fishes Mammals Amphibians Braincase 1 2 3 4 5 6 7 Evolutionary Tree of Vertebrates

25. Key Concepts Characteristics of Chordates Four traits characterize chordate embryos: a supporting rod (notochord), a dorsal nerve cord, a pharynx with gill slits in the wall, and a tail that extends past the anus Certain invertebrates and all vertebrates belong to this group

26. ANIMATION: Vertebrate Evolution To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERECLICK HERE

27. 24.3 The Fishes The number and diversity of fishes exceed those of all other vertebrate groups combined Fishes are divided into jawless and fishes with jaws Fishes with jaws are divided into cartilaginous fishes and bony fishes

28. Jawless Fishes The first fishes were jawless – two lineages survive – both have a cylindrical body, no fins or scales, and move with a wiggling motion hagfish Jawless fish with a cranium (skull case) but no backbone lamprey Jawless vertebrates with a backbone of cartilage Some are parasites of other fish

29. Two Modern Jawless Fishes Hagfish Parasitic lamprey

30. Fishes With Jaws Jawed fishes likely evolved from jawless ancestors when some gill supports became modified Jawed fishes typically have scales and paired fins Jawed fished are divided into the cartilaginous fishes and the bony fishes

31. Proposed Evolution of Jaws

32. Fig 24.5, p. 380 supporting structure for gill slits jaw, derived from support structure jaw location of spiracle (modified gill slit) jaw support gill slits Proposed Evolution of Jaws

33. jaw location of spiracle (modified gill slit) jaw support jaw, derived from support structure Fig 24.5, p. 380 supporting structure for gill slits gill slits Stepped Art Proposed Evolution of Jaws

34. Cartilaginous Fishes (Chondrichthyes) Cartilaginous fishes include sharks and rays Some sharks have rows of teeth, some are filter feeders Rays include filter feeders (mantas) and bottom feeders (stingrays) cartilaginous fish Fish with a skeleton of cartilage Gills are visible at the surface

35. Two Cartilaginous Fishes

36. Bony Fishes There are two lineages of bony fishes: Ray-finned fishes are the most diverse, including salmon, sardines, bass, swordfish, trout, tuna, halibut, carp, and cod Lobe-finned fishes include coelacanths and lungfishes

37. Key Terms bony fish Fish with a lung or swim bladder and a skeleton consisting largely of bone lobe-finned fish Fish with fleshy fins that contain bones ray-finned fish Fish with fins supported by thin rays derived from skin; member of most diverse lineage of fishes

38. Bony-Fish Body Plan Aspects of the fish body plan adapt fish to life in water: A swim bladder allows ray-finned fish to adjust its buoyancy Kidneys filter blood and adjust volume and solute composition Lungfishes have gills and one or two air-filled lungs

39. Body Plan of a Perch

40. Fig 24.7a, p. 381 liverintestine ovarynerve cord stomachanusgills brain heart swim bladder kidney Body Plan of a Perch

41. Ray-Finned Fish Diversity

42. ANIMATION: Bony fish body plan To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERECLICK HERE

43. Lungfish: A Lobe-Finned Fish Pelvic and pectoral fins are supported by bones

44. Fig 24.8, p. 381 pectoral finpelvic fin Lungfish: A Lobe-Finned Fish

45. Key Concepts The Fishes The first vertebrates were jawless fish Most modern fishes have jaws Sharks and their relatives are jawed fishes with a cartilage skeleton Ray-finned fishes and lobe-finned fishes are jawed bony fishes Ray-finned fishes are the most diverse vertebrate group

46. ANIMATION: Jawless Fishes To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERECLICK HERE

47. ANIMATION: Evolution of Jaws To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERECLICK HERE

48. ANIMATION: Cartilaginous Fishes To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERECLICK HERE