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Vertebrates v1.0

Vertebrates v1.0. The Chordates. Chordates (phylum Chordata ) are deuterostome coelomates -Nearest relatives are echinoderms (the only other deuterostomes). The Chordates. 1. Nerve cord 2. Notochord 3. Pharyngeal slits 4. Postanal tail. Four features characterize chordates .

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Vertebrates v1.0

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  1. Vertebrates v1.0

  2. The Chordates Chordates (phylum Chordata) are deuterostome coelomates -Nearest relatives are echinoderms (the only other deuterostomes)

  3. The Chordates 1. Nerve cord 2. Notochord 3. Pharyngeal slits 4. Postanal tail Four features characterize chordates

  4. The Nonvertebrate Chordates Nonvertebrates Phylum chordata can be divided into three subphyla 1. Urochordata 2. Cephalochordata 3. Vertebrata

  5. Subphylum Urochordata Tunicatesare marine animals -Larvae are tadpole-like and have notochord and nerve cord -Are free-swimming but do not feed -Adults typically lose the tail and notochord -Are immobile filter-feeders -Many secrete a tunic (cellulose sac) that surrounds the animal

  6. Subphylum Cephalochordata -Feed on plankton using cilia-generated currents -Closest relatives to vertebrates Lancelets are scaleless chordates -Notochord persists throughout animal’s life -Have no distinguishable head

  7. Subphylum Vertebrata Vertebrates: chordates with a spinal column -Distinguished from nonvertebrates by 1. Vertebral column – Encloses and protects the dorsal nerve cord 2. Head – Distinct and well-differentiated possessing sensory organs

  8. Subphylum Vertebrata Vertebratesalso have -Neural crest – A unique group of embryonic cells that forms many vertebrate structures -Internal organs – Liver, kidneys, endocrine glands, heart and closed circulatory system -Endoskeleton – Made of cartilage or bone -Makes possible great size and extraordinary movement

  9. Fishes Fishes have the following characteristics Vertebral column of bone or cartilage Jaws Paired appendages Internal gills Closed circulatory system

  10. History of the Fishes In the Carboniferous period (360-280 MYA), sharks (Class Chondrichthyes) became the dominant sea predators Evolved teeth Streamlined Lateral Line system. A light, flexible, calcified, cartilaginous skeleton, and paired fins made them superior swimmers

  11. History of the Fishes Bony fishes (Osteichthyes) evolved at the same time as sharks about 400 MYA Internal skeleton of bone. Swim Bladder Gill Cover--operculum Actinopterygii—ray-finned fishes. Bones in fins no muscle. Most fishes of today Sarcopterygii—fins with muscles, can function independently, few fishes, gave rise to….

  12. Amphibians Amphibians (class Amphibia) are damp-skinned vertebrates -First vertebrates to walk on land

  13. History of Amphibians Successful invasion of lands by vertebrates required several adaptations Legs to support body’s weight Lungs to extract oxygen from air Redesigned heart to drive larger muscles Pulmonary veins. Reproduction in H2O to prevent egg drying System to prevent whole body desiccation. The skin also aids in respiration. Coetaneous respiration.

  14. Reptiles Over 7000 species of reptiles (class Reptilia) now live on Earth All living reptiles exhibit three key features 1. Amniotic eggs, which are watertight 2. Dry skin, which covers body and prevents water loss 3. Thoracic breathing, which increases lung capacity

  15. Reptiles Reptiles, birds and mammals are amniotes The amniotic egg has four membranes Chorion – Allows O2 entry Amnion – Fluid-filled cavity Yolk sac – Provides food Allantois – Excretes wastes

  16. Modern Reptiles Modern reptiles developed two important characteristics: 1. Internal fertilization: Sperm fertilizes egg before protective membranes are formed 2. Improved circulation: Oxygen is provided to the body more efficiently

  17. Comparing the circulatory systems of fish, amphibians, and reptiles.

  18. Vertebrates 2

  19. Birds Birds (class Aves) are the most diverse of all terrestrial vertebrates Arose about 150 MYA; Archaeopteryx

  20. Birds Birds still retain many reptilian and dinosaur traits -Amniotic eggs and scales on legs; skeletal elements, DNA Two major traits distinguish them, however from dinosaurs: 1. Feathers -Provide lift for flight and conserve heat 2. Flight skeleton -Bones are thin and hollow -Many are fused (collarbone and keeled breastbone) 3. Physiological adaptations—efficient respiratory system.

  21. History of Birds 1. Efficient respiration -Air passes all the way through lungs in a single direction 2. Efficient circulation -Muscles receive fully oxygenated blood -Rapid heartbeat 3. Endothermy -Body temperature (40-42oC) permits higher metabolic rate

  22. Mammals There are about 4500 species of mammals (class Mammalia) -Lowest number among 5 vertebrate classes

  23. Mammals Mammals differ from other vertebrates in two fundamental traits: 1. Hair -Long, keratin-rich filaments that extend from hair follicles -Insulation, camouflage, sensory structure 2. Mammary glands -Females possess mammary glands that secrete milk

  24. Mammals Other notable features of mammals include: -Endothermy -Depends on more efficient: -Circulation – Four-chambered heart -Respiration – Diaphragm -Placenta -Specialized organ that brings fetal and maternal blood into close contact

  25. Mammals

  26. The Two Subclasses of Mammals Prototheria (most primitive) -Lay shelled eggs, oviparous -One living group -Monotremes Theria -Viviparous: Young are born alive -Two living groups -Marsupials and placental mammals

  27. Marsupials: Pouched Mammals Egg has chorion and amnion, but no shell Embryo is nourished by abundant yolk -After birth, it crawls into marsupial pouch -Latches onto nipple & continues to develop Examples: -Kangaroo -Opossum

  28. Placental Mammals Produce a true placenta that nourishes embryo throughout its development -Forms from both fetal and maternal tissue Includes most living mammals

  29. Evolution of Primates Primates are the mammals that gave rise to our own species -They evolved two features that allowed them to succeed in an arboreal environment 1. Grasping fingers and toes -First digit is opposable 2. Binocular vision -Eyes are shifted toward the front of the face

  30. Evolution of Primates Prosimians -Most are nocturnal -Only a few survive: -Lemurs, lorises and tarsiers About 40 MYA, the earliest primatessplit into two groups: prosimians and anthropoids

  31. The Anthropoids Anthropoids gave rise to two groups: New World Monkies All arboreal Flat, spreading noses Prehensile tails Old World monkeys and Hominoids (Apes and Humans) Ground-dwelling or arboreal None have prehensile tail

  32. Evolution of Primates The taxonomic group “apes” is paraphyletic Some apes are more closely related to hominids than to other apes. Living apes consist of gibbons, orangutans, gorillas and chimpanzees Hominids consist of humans and their direct ancestors Common ancestor was more like a chimpanzee than a gorilla

  33. Early Hominids There are two major groups of hominids -Genus Australopithecus -7 species -Older and smaller-brained -Genus Homo -3-7 species (depending how you count them)

  34. Bipedalism Bipedalism seems to have evolved as australopithecines left forests for grasslands Did it follow or precede brain enlargement? -African fossils demonstrate that bipedalism extended back 4 MYA -Substantial brain expansion, on the other hand, did not appear until about 2 MYA Therefore, upright walking came first -However, why it evolved is still a matter of controversy

  35. The Genus Homo Australopithecus afarensis Homo--2 MYA: Homo habilis H. Habilis Homo erectus Homo heidelbergensis (oldest) Homo neanderthalensis and Homo sapiens

  36. Out of Africa: Homo erectus H. Hablis was replaced by Homo erectus Homoerectus was a lot larger than H. habilis -Had larger brain and more rounded jaw -Able to talk H. erectus became widespread in Africa -Then migrated to Asia and Europe H. erectus survived for over a million years -Longer than any other human species

  37. Modern Humans Modern humans first appeared in Africa about 600,000 years ago -Three species are thought to have evolved -Homo heidelbergensis (oldest) -Homo neanderthalensis -Homo sapiens Some investigators lump all 3 into H. sapiens

  38. Modern Humans Neanderthals made diverse tools -Took care of sick and buried dead -First evidence of belief in “life after death” They abruptly disappeared about 34,000 years ago -Replaced by fossils of H. sapiens called the Cro-Magnons

  39. Out of Africa Hypothesis

  40. Our Own Species: Homo sapiens H. sapiens is the only surviving hominid -Best fossils are 90-100,000 years old Hallmarks of H. sapiens evolution -Progressive increase in brain size -Effective making and use of tools -Refined and extended conceptual thought -Use of symbolic language -Extensive cultural experience

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