1. Chapter 31: Animals Part II

2. Phylum Echinodermata Echinoderms: ◦ Radial symmetry as adults ◦ Endoskeleton of calcium-rich plates ◦ Spiny skin ◦ Unique water vascular system with tube feet ◦ Able to regenerate lost body parts ◦ Include sea stars, sea cucumbers, sea lilies, brittle stars, sea urchin, sand dollars (see. p.646 for pictures)

3. Phylum Echinodermata

4. Phylum Chordata 4 Chordate Characteristics: (have all 4 at some point in lifecycle) ◦ Segmented with a notochord (a dorsal supporting rod) ◦ Dorsal tubular nerve cord ◦ Pharyngeal pouches at some point of development (become gills in fish, auditory tubes in mammals) ◦ Post anal tail at some point in life cycle

5. Phylum Chordata

6. Subphylum Unicordata ◦ Sessile adult ◦ Encased in a tunic ◦ Lacks notochord and nerve cord as adult ◦ E.g. tunicates

7. Phylum Chordata Subphylum Cephalochordata: ◦ Retains the four chordate characteristics as adults ◦ Obvious segmentation throughout body ◦ E.g. Lancelets

8. Phylum Chordata Subphylum Vertebrata: ◦ Notochord is replaced by the vertebral column ◦ E.g. fishes, amphibians, reptiles (includes birds), mammals

9. Vertebrate Intro Have all 4 chordate characteristics at some point of development Embryonic notochord generally replaced by vertebral column Generally a high level of cephalization (brain and nervous system) with complex sense organs Closed circulatory system

10. Vertebrate Intro (cont’d) Jaw evolution allowed for easier predation Strong endoskeleton allows for large terrestrial organisms Complete digestive tract Generally, sexes are separate (not hermaphrodites) Sexual reproduction typical

11. Vertebrate Intro (cont’d) Evolution of amnion (extraembryonic membrane that encloses a fluid filled sac) Some lay shelled eggs Others are placental (e.g. mammals) and development of offspring occurs in female uterus

12. Fishes Evolutionary development: (from least to most evolved) 1.Jawless fishes (superclass Agnatha) a)About 63 species b)Cylindrical c)Up to 1 meter long d)Include hagfish and lampreys e)Some are parasitic

14. Fishes (cont’d) 2.Cartilaginous fishes (class Chondrichthyes) a)About 850 species b)Include rays, sharks and skates c)Have jaws (adapted gill arches – structure that supports gills) d)Skeletons made of cartilage (not bone) e)Well-developed senses make good predators: a)Ability to sense electric currents in water b)Have lateral line system that allows them to sense pressure changes in water from movement nearby c)Keen sense of smell

16. Fishes (cont’d) 3.Bony fishes (class Osteichthyes) a)About 20 000 species b)Most diverse class of all vertebrates c)Types of bony fishes: I.Ray-finned fishes i.Include fish we commonly eat: trout, cod, salmon ii.Have a pair of fins with thin bodies iii.Often have a swim-bladder, which regulates buoyancy iv.Water passes into mouth and out through gill slits: oxygen is absorbs and carbon dioxide given off v.Heart is simple pump with two chambers (one atrium and one ventricle)

18. Fishes (cont’d) II.Lobe-finned fishes i.Evolved into amphibians ii.Had fleshy appendages that were adapted to limbs for terrestrial life iii.Had a lung used for respiration iv.E.g. coelacanth, though extinct 20 000 years ago was discovered off the coasts of Eastern Africa

19. Fishes (Cont’d)

20. Amphibians Beginnings of adaptations to terrestrial life Amphibian = land and water (live parts of life cycle in both Some have lungs, other respire through skin Heart is 3 chambered (one ventricle) Ectothermic (cold-blooded – externally regulated body temperature)

21. Amphibians

22. Reptiles Include turtles, alligators, snakes, lizards, and birds Development of amniotic egg allowed for non-aquatic embryo development 3 chambered heart (e.g. snakes) and 4 chambered hearts (e.g. birds, crocodiles) present. (Fishes have only 2 chambers.) 4 chambers ◦ allows for more efficient metabolism ◦ Endothermic (self-regulating body temperature)

23. Reptiles

24. Mammals Major development: hair and mammary glands Includes: ◦ Monotremes  Lay hard-shelled eggs like birds  E.g. spiny anteater and duckbilled platypus ◦ Marsupials  Begin development inside female’s body and mature in pouch  E.g. kangaroos, opossum

25. Mammals

26. Mammals Placental Mammals Majority of mammals living today Internal in utero development of embryo Placenta is site of exchange between fetal and maternal blood Adapted fully to life on land (exception: dolphins and whales)

27. Mammals Highly developed brain 4 chambered hears Includes our order: primates. Adapted to arboreal life (life in trees) Many have opposable thumb and five digits on each of their four limbs Larger and more complex brain

28. Mammals

29. Summary Evolutionary adaptations: (in order of least to most advanced: (see p.649 for examples) ◦ Ancestral notochord ◦ Vertebrae ◦ Jaws ◦ Bony skeleton ◦ Lungs ◦ Limbs ◦ Amniotic egg ◦ Mammary gland