Three Domains of Life

1. Three Domains of Life

2. Kingdom Animalia • Eukaryotic (Domain Eukaryota) • Multi-cellular (unlike most Protists) • Lack cell walls (unlike Plants and Fungi) • Heterotrophic, by ingestion – Animals obtain their nourishment by ingesting other organisms (unlike Fungi)

3. Kingdom Animalia • Most animals are mobile • Sexual reproduction; haploid cells fuse directly to produce zygote, and no alternation of generations • Tissues – cells are organized into structurally functional tissues

4. Kingdom Animalia • Radial symmetry – body parts arranged around a central axis (simple) • Bilateral symmetry – body has a right and a left half that are mirror images of each other (advanced)

5. Kingdom Animalia • Evolution of a body cavity enabled the evolution of supporting organ systems and a means for distributing materials • The body cavity – a space surrounded by mesodermal tissue formed during development • Three germ layers: Ectoderm (outside), Mesoderm (middle), and Endoderm (inside)

7. Kingdom Animalia • Pseudocoelomates move nutrients and wastes through pseudocoel • Coelomates developed a circulatory system; blood carries oxygen, nutrients, carbon dioxide and wastes through (and out of) body

8. Kingdom Animalia • Circulatory system of Coelomates can be open or closed • In an open circulatory system, blood mixes with body fluids; bathes organs and cells directly; common to molluscs and arthropods • In a closed circulatory system, the blood never leaves a system of blood vessels and is pumped by the heart; common to all vertebrates, annelids and cephalopods

9. Kingdom Animalia • Segmentation of body parts • Succession (redundancy) of segments • Enables specialization of body segments • Individual segments may move independently to facilitate locomotion • In redundant segmentation, each segment contains most or all of the adult organ systems, such that damage to any one segment is not fatal to the organism

11. “Bilaterians exhibit two main types of development” – page 626 ...let’s come back to this (ignore for now)

12. Kingdom Animalia • Taxonomy (Domain Eukaryota, Kingdom Animalia, Phylum….)

13. Phylum Porifera (Sponges) • The simplest of animals • No nervous, digestive, or circulatory systems • Sessile • Lack germ layers • No defined symmetry

14. Phylum Cnideria • Nematocysts – stinging cells • Radial symmetry • “Jellyfish”, Corals, Sea anemones

15. Phylum Ctenophora (Comb jellies) • Colloblasts – sticky cells • Strictly marine • Largely bioluminescent

16. Phylum Platyhelminthes (Flatworms) • No body cavity • Half of all flatworms are parasitic (flukes, tapeworms, etc)

17. Phylum Nematoda (Round worms) • Pseudocoelomates • Can be free-living or parasitic http://www.attra.org/images/nematode/nematode.jpg

18. Guinea worm

19. Phylum Annelida (Segmented worms) • Coelomates • Oligochaetes (earthworms) and Polychaetes (bristle worms)

20. Phylum Mollusca • Mantle – secretes shell; forms siphon and external flaps • Bivalves (clams, mussels, etc), Snails, Squid, Octopus, Sea Slugs http://www.flickr.com/photos/ccahua/109008198/ http://www.flickr.com/photos/sabinche/424078457/

21. Phylum Arthropoda • “Jointed foot”; jointed limbs, rigid cuticle/exoskeleton • Insects, Arachnids, Crustaceans, and others – VERY SUCCESSFUL! http://www.flickr.com/photos/j-a-x/98046000/

22. Phylum Echinodermata • Strictly marine • Deuterostomes (we’ll come back to this) • “Spiny skin” • Includes sea stars, sea urchins, brittle stars

23. Phylum Chordata • Includes all vertebrates (Subphylum Vertebrata) • All have (at one stage of their life cycle) • A notochord – a flexible rod; “backbone” • A hollow, dorsal nerve cord; develops into spinal cord and brain • Pharyngeal slits* – filtering apparatus for feeding • An endostyle* – longitudinal ciliated groove in pharynx, produces mucus to capture food particles • A post-anal tail* *only present during embryonic stage in advanced vertebrates

24. All Chordates have all four of these characteristics at some time in their lives

25. Phylum Chordata • Includes 2 invertebrate groups (no vertebrae) • Urochordates – only the larvae has a notochord and nerve cord, adults usually lose tail; includes Tunicates and Salps (marine) • Cephalochordates – notocord persists throughout animal’s life; includes Lancelots; the closest relatives to the Vertebrates

26. Subphylum Urochordata (Tunicate)

27. Subphylum Cephalochordata (Lancelets)

29. Subphylum Vertebrata • A vertebral column – encloses and protects the dorsal nerve cord • A distinct head – houses sensory organs • Endoskeleton – made of cartilage or bone • Internal organs – liver, kidneys, endocrine glands, heart and closed circulatory system, etc.

30. Subphylum Vertebrata

31. Subphylum Vertebrata • The earliest vertebrates appeared in the oceans ~ 0.5 billion years ago (Cambrian period) Jawless fishes Cartilaginous fishes Bony fishes

33. Jawless fish (Lampreys)

34. Class Chondrichthyes (Cartilagenous)

35. Class Chondrichthyes • A light, flexible skeleton and paired fins made them superior swimmers • Sharks were among the first vertebrates to develop teeth

36. Bony Fishes • Evolved at same time as sharks (400 million years ago) • Heavy, internal skeleton made of bone • Possess a swim bladder and an operculum • Swim bladder – gas-filled sac enables fish to control their bouyancy • Operculum –hard plate that covers gills, flexes to permit water pumping

37. Bony Fishes

38. Amphibians • The first vertebrates to make it to land • Evolved ~300 million years ago

39. Class Reptilia • Reptiles evolved ~250 million years ago • Ectothermic (“cold-blooded”) • Evolution of the amniotic egg • Watertight, but permeable • Allows gas exchange and waste removal • Yolk sac provides food • Includes the dinosaurs!

40. Class Reptilia

41. Class Aves (Birds) • The most diverse group of all vertebrates • Like reptiles, have amniotic eggs and scales (on legs) • Feathers – enable flight and conserve heat • Flight skeleton • Bones are thin and hollow • Evolved directly from dinosaurs?

43. Class Mammalia • Hair – keratin-rich fibers; provides insulation, camouflage, and sensory structure • Mammary glands in females – secrete milk • Endothermy (“warm-blooded”) • Four-chambered heart • Evolved ~220 million years ago

44. Class MammaliaSubclass Prototheria • The “Monotremes” • Have single opening for digestive and reproductive tracts • Only 3 extant species – short and long-nosed echidna and duck-billed platypus

45. Class MammaliaSubclass Theria • Includes marsupial and placental animals • Marsupials – pouched animals; shell-less egg, embryo is nourished by yolk and after birth crawls into marsupial pouch where it latches onto nipple and continues to develop • Placental – includes most living mammals; produces a true placenta that nourishes embryo throughout its development

48. Modern humans first appeared in Africa ~600,000 years ago (Homo sapiens)