Vertebrates Chapter 17 The Chordates Chordates phylum Chordata
Vertebrates Chapter 17
The Chordates • Chordates (phylum Chordata) – Closest relatives are echinoderms • Four features all chordates share 1. _______ 2. Notochord 3. Pharyngeal slits 4. _______ 2
Vertebrates • Vertebrates also have – Neural crest – A unique group of embryonic cells that forms many vertebrate structures – _______– Liver, kidneys, endocrine glands, heart and closed circulatory system – _______ – Made of cartilage or bone • Makes possible great size and extraordinary movement 3
Fishes are the most diverse vertebrate group - ________________ -Vary greatly in size, shape, color and appearance 4
Fishes have the following characteristics 1. Vertebral column 2. Jaws and paired appendages 3. _________ 4. Single-loop _________ 5. Nutritional deficiencies 5
History of the Fishes • In the Carboniferous period (360 -280 MYA), sharks (Class Chondrichthyes) became the dominant sea predators – A light, flexible skeleton, and paired fins made them superior swimmers 6
History of the Fishes • Sharks were among the first vertebrates to develop ______ – Evolved from rough scales on mouth’s skin – Easily lost but continuously replaced (works as a conveyer belt) • Sharks (and bony fishes) have a fully developed _________ – Series of sensory organs under the skin that detects changes in pressure waves 7
History of the Fishes • Reproduction in sharks differs from that of other fishes – Shark eggs are fertilized internally, and pups are born alive – A few species do lay fertilized eggs – _________ sharks • Sharks have long gestation periods and relatively few offspring – Therefore, are not able to recover quickly from population ______ 8
History of the Fishes • Bony fishes- Class Osteichthyes evolved at the same time as sharks about 400 MYA – However, they adopted a heavy internal skeleton made completely of _____ • Bony fishes are the most species rich group of all vertebrates (> 30, 000 living species) • They developed significant adaptations that enabled them to dominate life in the water – _____________ 9
History of the Fishes • _________A gas-filled sac that Helps fish maintain buoyancy. • _________A hard plate, the operculum, covers gills – Its flexing permits water pumping over gills 10
History of the Fishes 11
Amphibians • Amphibians (class Amphibia) are dampskinned vertebrates – First vertebrates to walk on land • Amphibians have several key characteristics 1. 2. 3. Cutaneous respiration 4. 12 5. Partially divided heart
History of Amphibians • Successful invasion of lands by vertebrates required several adaptations 1. Legs to support body’s weight 2. Lungs to extract oxygen from air 3. Redesigned heart to drive _______ 4. Reproduction in ______ to prevent egg drying 5. System to prevent whole body desiccation 13
Modern Amphibians • Today there about 5, 670 species in 37 different families, comprising three orders: • Anura (“______”) • Caudata (“______”) • Apoda (“______”) 14
Modern Amphibians • Order Anura (frogs and toads) – Frogs have smooth, moist skin and long legs • Most live in or near water – Toads have bumpy, dry skin and short legs • ________________ – __________________ – Hatched into swimming tadpole larvae – Undergo metamorphosis into adults 15
Modern Amphibians • Order Caudata (salamanders) – Have long bodies, tails & smooth, moist skin – Live in moist places – Eggs are fertilized internally – ___________________ • Order Apoda (caecilians) – Tropical, _____________ – Legless with small eyes and jaws with teeth – Fertilization is internal 16
Modern Amphibians 17
Reptiles • Over 7000 species of reptiles (class Reptilia) now live on Earth • All living reptiles exhibit three key features 1. _______, which are watertight 2______, which covers body and prevents water loss 3. _________, which increases lung capacity 18
Reptiles • Reptiles, birds and mammals are amniotes • The amniotic egg has four membranes – Chorion – – Amnion – Fluid-filled cavity – Yolk sac – – Allantois – Excretes wastes 19
Reptiles 20
History of Reptiles • Reptiles dominated earth for 250 million years • Reptiles are distinguished by the number of holes on side of the skull behind eye orbit: 0( ), 1 ( ), 2 ( ) 21
Modern Reptiles • Modern reptiles developed two important characteristics: 1. ________: Sperm fertilizes egg before protective membranes are formed 2. ________: Oxygen is provided to the body more efficiently 22
Modern Reptiles • All living reptiles are ________ – Obtain heat from external sources • There are four surviving orders of reptiles – Chelonia (turtles and tortoises) – Rhynchocephalia (tuataras) – Squamata (lizards and snakes) – Crocodylia (crocodiles and alligators) 23
Order Chelonia • What’s the difference between turtles and tortoises? • Tortoises are _____ – Have dome-shaped shell • Turtles are mostly ______ – Have disc-shaped shells • Both lack teeth but have sharp beaks • Marine turtles must return to land to lay eggs 24
Order Rhynchocephalia • Contains only two species of tuataras -Large, lizardlike animals about half a meter long -Only found on islands near New Zealand • Feature a _________ • Inconspicuous “______” on top of head 25
Order Squamata • Contains about 3800 species of lizards and about 3000 species of snakes • A characteristic of this order is the presence of paired copulatory organs in the male 26
Order Squamata • Most lizards and snakes are carnivores – Only two species of lizards are venomous • ____________________ • Four of the 13 snake families contain venomous species – Elapids, sea snakes, vipers and colubrids 27
Order Crocodylia • Composed of 25 species of large, primarily aquatic carnivorous reptiles • Crocodiles live near or in water in tropical and subtropical regions – __________________ • Alligators exist in only two species – __________________ • Caimans are native to Central America • Gharials live only in India and Burma 28
Order Crocodylia Crocodile Gharial • In many ways, crocodiles resemble birds far more than they do other living reptiles – Build nests and care for their young – ___________________ 29
Birds (class Aves) are the most diverse of all terrestrial vertebrates -28 orders, 166 families, about 8600 species 30
Birds • Birds still retain many reptilian traits – Amniotic eggs and scales on legs • Two major traits distinguish then, however 1. ___________ – Provide lift for flight and conserve heat 2. _____________ – Bones are thin and hollow • Many are fused (collarbone and keeled breastbone) 31
History of Birds • Most paleontologists agree that birds are the direct descendants of theropod dinosaurs • Archaeopteryx is the first known bird -Had skull with teeth -Feathers on wings and tail -Forelimbs nearly identical to those of theropods 32
History of Birds • The most ancient living birds appear to be the flightless birds, such as ______ • The largest of the bird orders, Passeriformes, appears to have evolved the latest • Many adaptations enabled birds to cope with the heavy energy demands of flight 33
History of Birds 1. Efficient ________ -Air passes all the way through lungs in a single direction 2. Efficient ________ -Muscles receive fully oxygenated blood -Rapid heartbeat 3. ________ -Body temperature (40 -42 o. C) permits 34 higher metabolic rate
Mammals There about 4500 species of mammals (class Mammalia) -Lowest number among 5 vertebrate classes • Mammals differ from other vertebrates in two fundamental traits: 1. ______ -Long, keratin-rich filaments that extend from hair follicles -Insulation, camouflage, sensory structure 2. __________ -Females possess mammary glands that secrete milk 35
Mammals • Other notable features of mammals include: – ________ • Depends on more efficient: – Circulation – Four-chambered heart – Respiration – Diaphragm • -_______ • Specialized organ that brings fetal and maternal blood into close contact 36
Mammals 37
Mammals • The mammalian lineage also gave rise to several adaptations in some groups: 1. Specialized ______ -Different types of teeth are highly specialized to match particular eating habits 38
39
Mammals 2. Digestion of plants -Herbivorous mammals rely on mutualistic partnerships with ____ for cellulose breakdown 3. Development of hooves and horns -Hooves are specialized _______ pads -Horns are bone surrounded by ____ -Antlers are made of bone, not ____ 40
Mammals 4. Flying mammals: ____ -Bat wing is a leathery membrane of skin and muscle stretched over 4 finger bones -Bats navigate in the dark by ______ 41
The Two Subclasses of Mammals • Prototheria (most primitive) – _________ – One living group • ________ • Theria – Viviparous: Young are born alive – Two living groups • __________________ 42
Monotremes: Egg-laying Mammals • Only three living monotremes: -__________ -Short-nosed echidna -Long-nosed echidna -Have single opening, ____ for digestive and reproductive tracts 43
Marsupials: Pouched Mammals • Egg has chorion and amnion, but no shell • Embryo is nourished by abundant yolk -__________________ -Latches onto nipple & continues to develop • Examples: -_________ 44
Placental Mammals • Produce a true placenta that nourishes embryo throughout its development – ___________________ • Includes most living mammals 45
- Slides: 45