Transcript Chordates
Chordates Characteristics common to ALL chordates Dorsal nerve cord Pharyngeal slits Notochord Tail Dorsal nerve cord Pharyngeal Slits The wall of the pharynx is perforated by up to 200 vertical slits, which are separated by stiffening rods. Jawless to Jaw Used to collect food in an aquatic environment Notochord a flexible, rod-shaped body found in embryos of all chordates In lower vertebrates, it persists throughout life as the main axial support of the body, while in higher vertebrates it is replaced by the vertebral column. Tail Some animals lose tail during development Nonvertebrate chordates and Vertebrates Nonvertebrate chordates have a notochord (analogous to spinal chord) but lack a bony covering- the vertebrae Vertebrates have a spinal chord protected by bones Principle Chordate Features 13 The Nonvertebrate Chordates Tunicates (sea squirts) – exhibit neither a major body cavity nor visible segmentation tadpole larva clearly exhibits all basic characteristics of a chordate adults exist as sessile filter-feeders 14 Tunicates 15 The Nonvertebrate Chordates Lancelets – scaleless, fishlike marine chordates notochord runs entire length of dorsal nerve cord feed on microscopic plankton using cilia-generated current 16 17 Characteristics of Vertebrates Vertebral column Endoskeleton Distinct, well-differentiated head with cranium Closed circulatory system with chambered heart RBC’s with hemoglobin 18 Overview of the Evolution of Vertebrates Main CLASSES – Fishes – cartilaginous and bony – Amphibia - amphibians – Reptilia - reptiles – Aves - birds – Mammalia - mammals 19 Fishes Over half of all vertebrates are fishes. Characteristics (generally) – jaws and paired appendages (except lampreys and hagfish) – scales – fins – gills – single-loop blood circulation – Heart with 2 chambers (1 atrium, 1 ventricle) – Lateral line system 20 History of the Fishes Rise of active swimmers – Sharks and bony fishes replaced primitive fishes due to a superior swimming design. caudal (tail) fin dorsal (stabilizing) fins pectoral (shoulder - elevator) fins pelvic (hip- elevator) fins 21 Hagfish 22 23 Lamprey 24 History of the Fishes Sharks become top predators – Jaws with multiple rows of teeth – Paired pectoral and pelvic fins – Buoyancy from storing oil – extremely advanced reproduction shark eggs fertilized internally Most give birth to live young 25 Hammerhead Shark 26 Elephant Fish 27 Whale Shark 28 Tooth from Megalodon (left), and Great White 29 History of the Fishes Bony fishes dominate the water – Skeleton composed of bone – Swim bladder for bouyancy – Gills protected by operculum – highly mobile fins, thin scales, and completely symmetrical tails – Most have external fertilization and external development 30 Angler Fish 31 Deep Sea Angler Fish 32 Flounder 33 34 Electric Eel 35 Sea horse and Sea dragon 36 Another Sea dragon 37 Mola mola or Ocean sunfish 38 39 Coelacanth 40 Coelacanth fossils 41 Living Coelacanth 42 Shark Dissection Following is a series of video clips of dissection of various shark species. This will give you some idea of what you will encounter with our shark lab Lobe-Finned Fish and Primitive Amphibians 44 Amphibians Live on both land and in water (“double life”) Characteristics – legs – cutaneous respiration, lungs, gills – Heart with 3 chambers (double loop circulation) Pulmonary Systemic – External fertilization and development in nearly all 45 History of the Amphibians Adaptations for the invasion of land – legs to support body’s weight – lung to extract oxygen from the air – redesigned heart to drive new respiratory system – reproduction in water to prevent egg desiccation – system to prevent body desiccation 46 History of the Amphibians Amphibians today – Anura - amphibians without tails – most live in or near water, and return to water to reproduce eggs fertilized externally and hatch into tadpoles – metamorphosis 47 Poison dart frogs 48 Proboscis frog 49 African goliath frog 50 Jabba the Frog 51 Flying Frog 52 Chinese fire-bellied toad (most venomous) 53 History of the Amphibians – Urodela (Caudata) - salamanders have elongated bodies, long tails, and sooth, moist skin – fertilization is usually external 54 World’s largest salamander 55 Spotted salamander 56 Rodent surprise for lunch! 57 History of the Amphibians – Apoda caecilians - highly specialized group of tropical burrowing amphibians – legless, but have jaws and teeth – internal fertilization 58 Caecilian 59 Reptiles Characteristics – amniotic egg chorion - outermost membrane amnion - encases embryo yolk sac - surrounds yolk (food) allantois - surrounds waste cavity – dry skin with scales – Internal fertilization; usually external development 60 Baby komodo dragon 61 allantois airspace eggshell embryo albumen amnion chorion Yolk sac 62 Rise and Fall of Dominant Reptiles Dinosaurs: learning to run – body located directly over legs increased speed and agility 63 Apatosaurus 64 Triceratops 65 Diplodocus 66 Stegosaurus 67 Velociraptor 68 Another reconstruction of Velociraptor 69 Some pterosaurs were the size of small airplanes 70 71 Plesiosaurs were aquatic 72 Japanese fisherman caught this creature in 1977 73 Today’s Reptiles Of the 16 orders of reptiles that have existed, only 4 survive – turtles – lizards and snakes – tuataras – crocodiles 74 Rise and Fall of Dominant Other important Reptiles characteristics – internal fertilization – improved circulatory system – ectothermic - heat obtained from external sources – endothermic - generate own heat 75 Gaping is a means of cooling the blood 76 Living Reptiles Order Chelonia: turtles and tortoises – differ from other reptiles because their bodies are encased within a protective shell 77 Some tortoises have lived to 150 years 78 Green sea turtle 79 Pacific leatherback sea turtle 80 Rise and Fall of Dominant Reptiles Order Rhynchocephalia: tuatara – lizardlike animals about half a meter long – contain parietal eye – only found on island off New Zealand coast 81 82 Rise and Fall of Dominant Order Squamata:Reptiles lizards and snakes – three suborders Sauria - lizards Amphisbaenia - worm lizards Serpentes - snakes – paired copulatory organ in males – lower jaw not joined directly to skull 83 The chameleon is a lizard 84 Jackson’s chameleon 85 86 Gecko 87 Gila monster (venomous) 88 Skinks are sometimes called worm lizards 89 Blue-tongued skink 90 World’s smallest skink 91 Rainbow boa constrictor 92 93 Scarlet king snake 94 Coral snake 95 King or Coral? 96 Copperhead 97 Sidewinder rattlesnake 98 Rattlesnake victim 99 Rise and Fall of Dominant Order Crocodilia:Reptiles crocodiles and alligators – remained relatively unchanged only two species of alligators – southern US and China – resemble birds more than other living reptiles (care for young and four-chambered heart) 100 Nile crocodile 101 Caimans live in South America 102 Gharial 103 104 Birds Class Aves contains 28 orders containing 166 families and about 8,600 species. – key characteristics feathers – modified reptilian scales ? flight skeleton – thin, hollow bones 105 History of the Birds – Archaeopteryx (similar to modern Hoatzin) – Aves listed as separate class because of key evolutionary novelties of feathers, light bones, and super-efficient lungs 106 History of the Birds Birds today – adaptations for flight energy demands efficient respiration efficient circulation Endothermy 107 108 The “Great Nest” measures 9.5 ft. across, 20 ft. deep, and weighs an estimated 2 tons. 109 Mammals Key mammalian characteristics – hair heat loss camouflage sensory structures defense weapon – mammary glands about 50% of energy in milk comes from fat 110 A mother tiger, like other mammals, will not have to leave her young in order to find food for them Key Mammalian Characteristics endothermy – crucial adaptation that allowed activity at any time of the day to colonize severe environments placenta – specialized organ allowing food, water, and oxygen to pass from mother to child teeth – heterodont dentition (different teeth for different functions) 112 Neither of these animals is a fierce carnivore, despite the appearance of their teeth Key Mammalian Characteristics digestion of plants – cellulose major source of food for herbivores mammals do not have necessary digestive enzymes to break apart cellulose – some have evolved four-chambered stomachs – some contain mutualistic bacteria in a cecum 114 Giraffes, like cows, possess a chambered stomach. All ruminants chew cuds Although horses and zebras are herbivorous like giraffes, they do not have a rumen. Instead, they possess a cecum. Key Mammalian Characteristics hooves and horns – hooves specialized pads of keratin – horns composed of core of bone surrounded by keratin sheath flight – bats have wing of leathery membrane of skin stretched over the bones of four fingers second largest order of mammals – echolocation 117 History of the Mammals Orders of mammals – monotremes: egg-laying mammals lay shelled eggs – marsupials: pouched mammals finish development in external pouch – placental mammals placenta nourishes embryo throughout entire development Gestation length related to size 118 echidna The echidna is also known as the spiny anteater koala Koala young stay with the mother for an extended period of time, hitching a ride on mom’s back They’re even cute when they’re asleep Tasmanian devil There really is a Tasmanian devil Tasmanian Devil kangaroo There are many species of kangaroo. In addition to the red (shown here), there is even a species that climbs trees You didn’t believe me, did you? The capybara is the world’s largest rodent. sloth Star nosed mole Manatee? Manatees are very docile creatures Notice the teeth on this orca Beluga whale The blue whale can measure over 90 ft. long and weigh over 200 tons Evolution Among Primates Primates – two distinct features allowed them to succeed in arboreal environment: grasping fingers and toes binocular vision Prosimians (lemurs and tarsiers) – Very smell oriented – Usually have long tails 133 The tamarin is a prosimian The aye-aye is a most unusual prosimian Anthropoids Higher primates - includes apes, monkeys, and humans – The term “Anthropoid” means “Like us” Direct descendents: – New World monkeys (South America) – Old World monkeys (Africa) 136 mandrill The mandrill is an anthropoid monkey related to the baboon New world monkeys like this spider monkey have prehensile or grasping tails. The Old World monkeys lack the ability to grasp with the tail The “silverback” is a mature male gorilla who fears nothing gorilla The orangutan is found only on orang Borneo and Sumatra Gibbons are gibbon extremely athletic apes found in Southeast Asia. Like all apes, gibbons are tail-less Chimpanzees have very complex social groups, interact often with one another, and are very devoted parents Chimps have often been seen in the wild using tools. What do you suppose this guy is doing with the stick? Human evolution is very controversial Fossils are extremely rare and difficult to interpret Dating of fossils is also suspect H. sapiens is the only surviving hominid. – The best fossils are between 90,000 and 100,000 years old. – Cro-Magnons replaced Neanderthals about 40,000 years ago. – Humans of modern appearance eventually spread across Siberia to North America about 13,000 years ago. 144 145