1. Phylum Chordata 09 June 2015Chordata.ppt1

2. 09 June 2015Chordata.ppt 2 Phylum Chordata Latin: with a cord, = notochord Notochord Dorsal nerve cord Pharyngeal arches/clefts bear gills in fishes, modified to other structures in terrestrial animals Post-anal tail

3. 09 June 2015Chordata.ppt3 Phylum Chordata Subphylum Urochordata (= tunicates) Subphylum Cephalochordata (= lancelets) Subphylum Vertebrata

4. 09 June 2015Chordata.ppt4 Invertebrate Chordates Two Subphyla of Chordata, lack distinguishing characters of Vertebrata:  Subphylum Urochordata tunicates, sea squirts  Subphylum Cephalochordata lancelets, amphioxus

5. Subphylum Urochordata Adults (= tunicates) Sessile filter feeders Ciliated pharynx NO notochord Ganglion between siphons, but NO nerve cord 09 June 2015Chordata.ppt5

6. Subphylum Urochordata 09 June 2015Chordata.ppt6 Larva “tadpole larva” exhibits characters of Chordata Notochord Pharyngeal arches Dorsal nerve cord Post-anal tail

7. 09 June 2015Chordata.ppt7 Subphylum Cephalochordata “lancelets”

8. Adults & larvae Filter feeders Ciliated tentacles and pharynx Filtered food passes into intestine Gas exchange through epidermis Pharnygeal arches are NOT “gills” 09 June 2015Chordata.ppt8

9. 09 June 2015Chordata.ppt9 Phylum Chordata Subphylum Vertebrata Notochord reduced, replaced by bony or cartilaginous vertebrae Some notochord tissue usually remains Pharyngeal arches bear gills or developed into other organs: hyoid bone, larynx Liver Pancreas

10. 09 June 2015Chordata.ppt10 Phylum Chordata Subphylum Vertebrata Classes (?): Jawless fishes Cartilaginous fishes Ray-finned (Bony) fishes (Actinopterygii) Lobe-finned fishes (Sarcopterygii) Amphibians Reptiles, including Birds Mammals

11. 09 June 2015Chordata.ppt11 Subphylum Vertebrata “Fishes”

12. 09 June 2015Chordata.ppt12 Fishes Aquatic & Marine fishes retain four (4) primitive characters: Streamlined body Vertical tail fin Gills for gas exchange Lateral line system, No ears

13. 09 June 2015Chordata.ppt13 “Jawless Fishes” Survivors of earliest vertebrates No jaws, can not close mouth No scales No paired fins, only median tail fin (continues dorsal & ventral to anus) Single median nostril on top of head Circular gill slits 7 or 12 pairs on sides of pharynx.

14. 09 June 2015Chordata.ppt14 Myxini, Hagfishes Hagfishes Rudimentary head skeleton No true vertebrae tentacles around mouth predators on worms, mollusks scavengers 20 spp. in 4 genera

15. 09 June 2015Chordata.ppt15 Petromyzonida, Lampreys Lampreys circular mouth with “horny” teeth, Rings of cartilage around notochord = vertebrae filter feeders, or external parasites of bony fishes 30 spp. in 10 genera

16. 09 June 2015Chordata.ppt16 Development of Jaws Jaws developed from gill arch, Maxilla (upper) Mandible (lower) Allowed diverse diet: herbivores, predators Hyoid arch developed from second arch

17. 09 June 2015Chordata.ppt17 Class Chondrichthyes About 750 species Skeleton of cartilage, bone lost.  Fossil placoderms and jawless fishes had bone tissue, prob. ancestral to both Cartilaginous & Bony fishes.

18. 09 June 2015Chordata.ppt18 Class Chondrichthyes Cartilaginous skull poorly developed, esp. dorsal to brain Fins supported by cartilage or horn-like rays

19. 09 June 2015Chordata.ppt19 Cartilaginous Fishes No ribs. No lungs or swim bladder. Separate gill slits, usually 5 Placoid scales, tiny, tooth-like Enlarged at edge of mouth  teeth Homologous to teeth in all later vertebrates. Marine Retain urea for osmoregulation

20. 09 June 2015Chordata.ppt20 “Bony Fishes” ~30,000+ species. Majority of living vertebrate species. Bony skeleton, well developed skull, Fins supported by cartilage or bony “rays” and minute scales, Or, “fins” developed into “limbs.”

21. 09 June 2015Chordata.ppt21 “Bony Fishes” Diversification of “bony fishes” Most remain “fishes” (Actinopterygii) Sarcopterygii developed strong bones and muscle in fin bases Able to “walk” on land Dipnoi adapted to intermittent streams, stagnant pools Tetrapods adapted to move well on land.

22. 09 June 2015Chordata.ppt22 Class Actinopterygii Bony dermal scales covered by thin epidermis NOT homologous to reptilian scales. Operculum covers gills; one gill slit each side. Lungs, often modified to swim bladder.

23. Class Actinopterygii Examples: sturgeons gars catfish trout bass Northern pike American eel note paired fins, jaw, operculum 09 June 2015Chordata.ppt23

24. 09 June 2015Chordata.ppt24 Actinistia & Dipnoi Actinistia Rhipidistians extinct Coelocanths thought extinct until 1938 Western Indian Ocean Newly discovered population in Indonesian waters Dipnoi (“2 lungs”) Australian and African lungfishes

25. 09 June 2015Chordata.ppt25 Tetrapods Adapted to move easily and efficiently on land Loss of fin tissue on limbs Digits (5 per limb) Longer, stronger limbs Lift belly off of ground

26. 09 June 2015 Chordata.ppt26 Class Amphibia Old group of tetrapod (4-footed) vertebrates, older than reptiles. Origin in mid-Paleozoic (Carboniferous period)

27. 09 June 2015 Chordata.ppt27 Class Amphibia Less well adapted to terrestrial environment Smooth skin, no scales (no keratin ?) External fertilization depend on water for mating; sperm and eggs released together into water No embryonic membranes, Egg must stay moist usually in water, rarely in moist soil

28. 09 June 2015 Chordata.ppt28 Amphibian Life Cycle Larvae (immature form, tadpoles) hatch in water, Gills for gas exchange. Tail Metamorphosis to adult form growth of limbs development of lungs and loss of gills loss of tail in frogs, toads Adult usually terrestrial, some exceptions

29. 09 June 2015 Chordata.ppt29 Class Amphibia Order Urodela (Salamanders)  Primitive form with four equal legs  Retain tail

30. 09 June 2015 Chordata.ppt30 Class Amphibia Order Anura (Frogs)  Tail lost in metamorphosis  Hind legs enlarged, hopping or leaping locomotion

31. 09 June 2015 Chordata.ppt31 Class Reptilia

32. 09 June 2015 Chordata.ppt32 Class Reptilia Old group of tetrapod (4-footed) vertebrates Origin in Carboniferous; Diverse in Permian (end of Paleozoic)

33. 09 June 2015 Chordata.ppt33 Class Reptilia Successful terrestrial vertebrates Ancestral fishes and amphibians incompletely adapted to land A few fishes can survive out of water for several hours Lungfishes survive droughts of several months Amphibian adults live on land, but must mate & lay eggs in water Most reptiles never go into the water.

34. Reptiles’ success 3 adaptations to terrestrial environment  Keratinized skin epidermal scales reduce water loss abrasion resistant  Internal fertilization Sperm deposited in female body  Amniote egg 09 June 2015 Chordata.ppt34

35. Amniote egg Embryo develops membranes within shell amnion, chorion, yolk sac, allantois Shell permeable to air (breathes) Amnion, chorion retain water to keep embryo wet. 09 June 2015 Chordata.ppt35

36. 09 June 2015 Chordata.ppt36 Modern Reptiles traditional Class Reptilia Retain primitive characters Epidermal scales of keratin also: hair in mammals, feathers in birds, scales on bird’s feet Five toes per foot with claws (derived from scales).

37. 09 June 2015 Chordata.ppt37 Modern Reptiles: Diapsids Order Lizards (includes Snakes) Forked tongue Fracture plane in tail (lost in snakes ?) Paired hemipenes in males

38. 09 June 2015 Chordata.ppt38 Modern Reptiles: Anapsids Order of turtles 200+ species Bony plates form shell carapace plastron

39. 09 June 2015 Chordata.ppt39 Modern Reptiles: Diapsids Two holes in “bony roof” Order Crocodilians Hard palate (differs from mammal’s) Tongue fused to lower jaw Ball-and-socket joints between trunk vertebrae

40. 09 June 2015 Chordata.ppt40 Reptiles: Diapsids Two holes in “bony roof” Order Dinosaurs Suborder Ceratopsians Suborder Duckbilled dinos. Suborder Sauropods Suborder Theropods Include Birds