2 What is a Chordate?All chordates have 4 basic features that are present at some point during their life cycleHollow Nerve Cord – Nerve cord in which nerves branch out at regular intervalsNotochord – Long supporting rod that runs throughout bodyPharyngeal Pouches – Paired structures in throatMuscular Tail – Extends beyond anusOnly 4-5% of animals are chordatesExamples = Fish, Amphibians, Reptiles, Birds
4 The Generalized Structure of a Chordate Section 30-1Muscle segmentsTailAnusPharyngeal pouchesMouthHollow nerve cordNotochord
5 Fish – Basic FactsFish live in nearly every single aquatic habitat imaginableFish are aquatic vertebrates characterized by fins, scales, and gillsFish were the first vertebrates to evolve.Fish bring in Oxygen rich water through gills and remove oxygen poor water through gill slitsClosed circulatory systemFour chambered heartSwim bladder controls buoyancyMost are egg layingMost move by contracting opposite muscles (S Shaped)
6 Groups of Fish Jawless Fish – Have mouths of soft tissue with no true teeth.Have no bonesOnly vertebrates with no vertebral column as adultsLampreys, HagfishCartilage Fish –Skeleton built entirely of cartilageHave jaws, toothlike scales, and paired finsSharks, sea raysBony Fish–Skeleton made of bonesHave flap that covers and protects gillsCarp, sea horse, perch, etc.
8 Amphibians – Basic Facts Amphibian = “double life”Live in both water and landMost larvae are fishlike; adults are terrestrial carnivoresLarvae respire through skin/gills; Adults use lungsDescendants of ancestral organisms that evolved some, not all, adaptations for life on landFirst appeared 360 million years agoExternal fertilizationClosed circulatory system; three chambered heart
9 The Life Cycle of a Frog Section 30-3 Adult Frog Young Frog Adults are typically ready to breed in about one to two years.Young FrogFrog eggs are laid in water andundergo external fertilization.The eggs hatch into tadpoles a few days to several weeks later.Fertilized EggsTadpolesTadpoles gradually grow limbs, lose their tails and gills, andbecome meat-eaters as they develop into terrestrial adults.
10 Section 30-3 Amphibians means “Double life” as larvæ they live in adults they live onWaterLandand have special adaptations such asBonesLungsRibsarethat allow forthat allowthat provideEfficient movementBreathing airSupport and protectionare
11 Groups of Amphibians Salamanders – Long bodies and tails Adults are carnivorousUsually live in moist woodsFrogs and Toads –Lack tailsFrogs have long legs and are usually tied to waterToads have shorter legs and not as closely tied to waterCaecilians –Legless animals that burrow in moist soilHave fishlike scales
13 Reptiles – Basic Facts All reptiles have: Dry, scaly skin – helps prevent loss of body water in dry environmentsTerestrial eggs – first animals to develop amniotic eggs that didn’t need to be deposited in waterRespire using lungsInternal Fertilization; Most are egg-layingEctotherms – cannot internally regulate body temperature; cannot live in cold climatesBehavior controls body temp. (swimming, burrowing, basking, etc.)Closed circulatory system; double loop;Heart = two atria/one or two ventricles
14 Groups of Reptiles Lizards and Snakes Have legs & clawed toes (lizards) external ears, moveable eyelidsHighly evolved specialized forms (venom)Crocodiles and AlligatorsLong, typically broad snout and squat appearanceAll are carnivorousProtective of young; carry hatchlings in their mouthLive in tropics and subtropicsAlligators live in freshwaterCrocodiles live in fresh or saltwater
15 Groups of Reptiles (con.) Turtles and Tortoises –All are shelledTurtles are aquatic; tortoises are terrestrialTuatara –Primitive reptiles found on small, remote islands
18 Birds – Basic Facts Nearly 10,000 modern bird species Birds are closely related to reptiles (scales on legs)Have outer covering made of feathers, two legs used for walking or perching, and forelimbs modified into wingsFeathers separate birds from all other animal speciesFeathers provide insulation for warmth; can generate on body heatBeak/Bills adapted to type of food they eatHighly efficient respiratory system; lungs only exposed to Oxygen rich airInternal fertilization; amniotic eggs; many mate for life
19 Birds Section 31-2 have the following adaptations to flight Wings FeathersStrong chest musclesEfficient respiratory systemEfficient circulatory systemwhich arethat alsothat powerthat providethat ensureHomologous to front limbs in other vertebratesProvide warmthUpward and downward wing strokesOne-way flow of O2-rich airO2 distribution to body tissues
20 Groups of Birds More than thirty orders of birds Some of the most commonPerching Birds – largest order; many are songbirds (sparrows, crows, cardinals, etc.)Birds of Prey – fierce predators with hooked bills; large talons (condors, hawks, owls, eagles, etc.)Herons & Relatives – Wade in aquatic habitats (storks, herons, cranes)Ostriches & Relatives – flightless birds move by running or swimming (ostriches, emus, etc.)
22 Mammals – Basic FactsFirst true mammals appeared 220 million years agoMammals flourished after dinosaurs became extinct – 65 million years agoBasic characteristicsHairMammary glands – produce milk to nourish youngBreathe airFour chambered heartEndotherms – can generate own body heatInternal fertilization; care for young
23 Orders of Placental Mammals Section 32-2Orders of Placental MammalsOrderInsectivoresSireniansCetaceansChiropteransRodentsCharacteristicsExamplesLong, narrow snouts, sharp clawsWater-dwelling, slow-movingLive and breed in ocean, come to surface to breatheWinged, capable of true flightSingle pair of long, curved incisor teeth in upper and lower jawsShrews, hedgehogs, molesManatees, dugongsWhales, dolphinsBatsMice, rats, voles, squirrels, beavers, porcupines, chinchillas
24 Orders of Placental Mammals Section 32-2Orders of Placental MammalsOrderPerissodactylsCarnivoresArtiodactylsProboscideansCharacteristicsExamplesHoofed, with an odd number of toes on each footSharp teeth and clawsHoofed, with an even number of toes on each footTrunksHorses, tapirs, rhinoceroses, zebrasTigers, hyenas, dogs, foxes, bears, raccoons, walrusesCattle, sheep, goats, pigs, ibex, giraffes, hippopotami, camelsAsian and African elephants, mastodons and mammoths
25 Orders of Placental Mammals Section 32-2Orders of Placental MammalsOrderLagomorphsXenarthransPrimatesCharacteristicsExamplesTwo pairs of incisors in upper jaw, hind legs allow leapingNo teeth (or very small teeth in the back of the jaw)Highly developed cerebrum and complex behaviorsSnowshoe hares, rabbitsSloths, anteaters, armadillosLemurs, tarsiers, apes, gibbons, macaques, humans
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