Chapter 24 Animals II: The Chordates (Sections 24.1 - 24.3)

1. Chapter 24Animals 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. Lancelets Fig 24.1a, p. 378

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

11. Lancelets Fig 24.1b, p. 378

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

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

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

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 HERE

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

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

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

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. Body Plan of a Perch swim bladder kidney ovary nerve cord brain anus intestine stomach liver heart gills Fig 24.7a, p. 381

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 HERE

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

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

45. Key Concepts • The Fishes • The first vertebrates were jawless fish • Most modernfishes 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 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 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 HERE