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Chapter 26: Animals – The Vertebrates Characteristics of Chordates Bilateral Some species are invertebrates but the vast majority are vertebrates Vertebrates – chordates with a backbone and a brain located inside a protective chamber Chordate – an animal that exhibit the following 4 main features. In many cases these features are temporary, appearing only during embryonic development 4 Features Evident in Chordate Embryos 1. Notochord – a long rod of stiffened tissue (not cartilage or bone), helps support the body 2. Nerve Cord – nervous system develops from this tubular structure. Anterior end increases in mass and forms brain 3. Pharynx – for feeding and/or respiration. Has distinctive slits in the wall 4. A tail forms in embryos and extends past the anus Chordate Classification 3 Subphyla of Chordates 1. Urochordata – tunicates 2. Cephalochordata – lancelets 3. Vertebrata 8 Classes of Vertebrates 1. Agnatha – jawless fish 2. Placodermi – jawed, armored fish (extinct) 3. Chondrichthyes – cartilaginous fish 4. Osteichthyes – bony fish 5. Amphibian – amphibians 6. Reptilia – reptiles 7. Aves – birds 8. Mammalia – mammals Invertebrate Chordates Tunicates Sea squirts In marine habitats Most adults remain attached to rocks Filter feeders – water flows in siphon and passes through gill slits, and out another siphon Once sea squirt reaches adult stage its tail and notochord disappear A very simplified nervous system Lancelets Live in nearshore marine sediments around the world Most of time buried in sand Lancelet refers to the sharp tapering of their body Have a closed circulatory system, but no red blood cells Filter feeders No brain Existing Jawless Fishes (Ostracoderms) Ex. Hagfish and lampreys 75 species Cylindrical body and a skeleton of cartilage Hagfish prey on worms or scavenge Lampreys are parasitic and have a sucker like oral disk Existing Jawed Fishes (Placoderms) Vertebrate fish outnumber all other vertebrates Swim Bladder – an adjustable flotation device that exchanges gases with blood Scales – small bony plates at the body surface that protect body without weighing it down Cartilaginous Fishes (Chondrichthyes) Skates, sharks, rays Predators Prominent fins Skeleton of cartilage 5-7 gill slits Scales are small Bony Fishes (Osteichthyes) Most numerous and diverse vertebrates Body plans very greatly 3 lineages 1. Ray-finned fishes 2. Lobe-finned (1 species remains today) 3. Lungfish (3 species remain today) Origin of Amphibians Lobed finned fish probably pulled themselves up out of dried up ponds to ones that still had water. They gulped air and had lungs Amphibian – a vertebrate with a body plan and reproductive mode somewhere between fishes and reptiles Most have largely bony endoskeleton Four legs Salamanders, frogs, toads, have not escaped water entirely Even with lungs or gills, they can use their thin skin as a respiratory surface Respiratory surfaces must be kept moist Salamanders Newts Like fishes and early amphibians salamanders bend from side to side when they walk Carnivores Toads and Frogs Long hindlimbs and powerful muscles allow them to catapult through the air or water Sticky-tipped tongue for catching prey Frogs have mucus and poison glands. Poison types have bright coloration The Rise of Reptiles A divergence from the amphibian lineage gave rise to reptiles First to escape dependency on standing water Have tough dry scaly skin that restricts loss of water Fertilization is internal. Sperm do not require free water to reach eggs Kidneys are good at conserving water Amniote Egg – egg that has an extra embryonic membranes and often a shell. Embryo develop to an advanced stage before hatching Early reptiles chased prey with far greater cunning and speed Limbs were more efficient at supporting the trunk of the body on land Nervous system increased in complexity Crocodilians were the first animals with a muscular four-chambered heart fully separated into 2 halves Reptiles depend on lungs not skin for gas exchange Crocodilians Closest relatives of birds and dinosaurs Live in or near water Adjust body temperature with behavioral and physiological mechanisms Like birds in social behaviors when parents guard nests and assist hatchlings into water Turtles Live inside shell that is attached to skeleton Have tough horny plates instead of teeth Lay eggs on land then leave them Lizards and Snakes 95% of reptiles Short-legged long-bodied lizards gave rise to the elongated limbless snake Some snakes have bony remnants of ancestral hindlimbs All snakes are carnivores Snakes usually do not act aggressively toward humans Tuataras Have a third “eye”. It can only register changes in daylength and light intensity Engage in sex after 20 years old Look like a lizard Birds (Aves) Feathers – lightweight structures derived from skin, are used for flight body insulation or both Birds descended from tiny reptiles that ran about on 2 legs Feathers evolved as highly modified reptilian scales Birds have scales on legs Lay eggs Differ greatly in body size, proportions, coloration, and capacity for flight Large durable 4 chambered heart The Rise of Mammals Mammals – vertebrates with hair and mammary glands A few aquatic mammals – whales, dolphins, manatees, platypuses, otters Care for young for an extended period Adults serve as model for their behavior Behavioral Flexibility – a capacity to expand on basic activities with novel forms of behavior Cerebral Cortex – outermost layer of the forebrain receives, processes and stores information from sensory structures and it issues commands for complex responses Primates have most highly developed cerebral cortex Most mammals secure, cut and sometimes chew food before swallowing Dentition – type, number, and size of teeth differ from reptiles Have 4 types of upper and lower teeth 1. Incisors – nip or cut food 2. Canines 3. Premolars – crush grind shear 4. Molars – crush grind shear Teeth offer clues to life styles Portfolio of Existing Mammals 3 lineages of Mammals 1. Monotremes – egg laying mammals 2. Marsupials – pouched mammals 3. Eutherians – placental mammals Spiny anteaters and duck billed platypus are the only living monotremes Most marsupials are native to Australia Newborns finish development in a permanent pouch on the mother Placenta – a spongy tissue of maternal and fetal membranes. Forms inside pregnant females uterus Grow faster in placenta then in marsupial pouch Primate Classification Order Primates – prosimians, tarsioids, anthropoids 4. 5. Prosimians dominated forests millions of years ago Anthropoids – monkey, apes, humans Apes are closer to humans than monkeys in comparing biochemistry Hominids – humanlike and human species of a line of descent that started with its divergence from apes Most are arboreal or tree dwellers 5 Trends helped to define lineage leading to humans 1. Less reliance on sense of smell and more on vision Eyes are forward directed Respond to variations in color and light intensity 2. Skeletal changes led to upright walking, which freed hands Bipedalism – walk on two legs 3. Changes in bones and muscles led to refined hand movements Opposable thumb led to a precision grip (holding a pen) Teeth became less specialized Evolution of the brain, behavior and culture Parents put more effort in fewer offspring and formed stronger bonds Language developed From Early Primates to Hominids Origins and Early Divergences Primates evolved from mammals more than 60 million years ago First ones resembled small rodents Stayed in trees because abundant food and safety Climate changed so they had to move out of the trees or die One lineage gave rise to great apes and other gave rise to the first hominids The First Hominids Australopiths – southern apes Australopiths has a large face, protruding jaws, small skull and brain Were apelike in many skeletal ways but humanlike in walking upright Australopithecus afarensis – “Lucy” 3.2 million years old Emergence of Early Humans The brain sets humans apart from apes Earliest humans – Homo habilis means handy human A great stone tool maker Homo erectus – means upright man Clearly related to modern humans Traveled out of Africa to Europe, Asia Larger brain More advanced tool maker Built fire Used furs for clothing Homo sapiens Means wise man Evolved 100,000 years ago Smaller teeth and jaw Larger brain Developed complex language Neandertals Lived in Europe 200,000 – 30,000 years ago Massively built and large brain Their disappearance coincided with the appearance of anatomically modern humans in the same regions about 40,000 – 30,000 years ago. We have no evidence that they interbred with the later arrivals Neandertal DNA has unique sequences, so they might not have contributed to the gene pools of modern European populations We still do not know what happened to them Humans spread rapidly through the world by devising cultural means to deal with a broader range of environments. Chapter 26: Animals – The Vertebrates Characteristics of Chordates Some species are invertebrates but the vast majority are vertebrates Vertebrates – Chordate – an animal that exhibit the following 4 main features. In many cases these features are temporary, appearing only during embryonic development 4 Features Evident in Chordate Embryos 1. Notochord – 2. Nerve Cord – 3. Pharynx – 4. A tail forms in embryos and extends past the anus Chordate Classification 3 Subphyla of Chordates 1. Urochordata – 2. Cephalochordata – 3. Vertebrata 8 Classes of Vertebrates 1. Agnatha – 2. Placodermi – 3. Chondrichthyes – 4. Osteichthyes – 5. Amphibian – 6. Reptilia – 7. Aves – 8. Mammalia – Invertebrate Chordates Tunicates Most adults remain attached to rocks Filter feeders – Once sea squirt reaches adult stage its tail and notochord disappear A very simplified _______________ system Lancelets Live in nearshore marine sediments around the world Most of time buried in sand Lancelet refers to the sharp tapering of their body Have a ____________ circulatory system, but no red blood cells Existing Jawless Fishes (Ostracoderms) Ex. Cylindrical body and a skeleton of cartilage Hagfish prey on worms or scavenge Lampreys are parasitic and have a sucker like oral disk Existing Jawed Fishes (Placoderms) Vertebrate fish outnumber all other vertebrates Swim Bladder – Scales – Cartilaginous Fishes (Chondrichthyes) Bony Fishes (Osteichthyes) Most numerous and diverse vertebrates Body plans very greatly 3 lineages 1. 2. 3. Origin of Amphibians Lobed finned fish probably pulled themselves up out of dried up ponds to ones that still had water. They gulped air and had lungs Amphibian – Most have largely bony endoskeleton Salamanders, frogs, toads, have not escaped water entirely Even with lungs or gills, they can use their thin skin as a respiratory surface Respiratory surfaces must be kept __________ Salamanders Like fishes and early amphibians salamanders bend from side to side when they walk Toads and Frogs Long hindlimbs and powerful muscles allow them to catapult through the air or water Sticky-tipped tongue for catching prey Frogs have mucus and __________ glands. Poison types have bright coloration The Rise of Reptiles A divergence from the amphibian lineage gave rise to reptiles First to escape dependency on standing ____________ Have tough dry scaly skin that restricts loss of ____________ Fertilization is ____________. Sperm do not require free water to reach eggs ____________ are good at conserving water Amniote Egg – Early reptiles chased prey with far greater cunning and speed Limbs were more efficient at supporting the trunk of the body on land Crocodilians were the first animals with a muscular four-chambered heart fully separated into 2 halves Reptiles depend on __________ not skin for gas exchange Crocodilians Closest relatives of __________ and _______________ Adjust body temperature with behavioral and physiological mechanisms Like birds in social behaviors when parents guard nests and assist hatchlings into water Turtles Live inside shell that is attached to _______________ Have tough __________ __________ instead of teeth Lay eggs on land then leave them Lizards and Snakes _______ of reptiles Short-legged long-bodied lizards gave rise to the elongated limbless snake Some snakes have bony remnants of ancestral hindlimbs All snakes are _______________ Snakes usually do not act aggressively toward humans Tuataras Have a third “eye”. It can only register changes in daylength and light intensity Engage in sex after _______ years old Look like a _______________ Birds (Aves) Feathers – Birds descended from tiny _______________ that ran about on 2 legs Feathers evolved as highly modified reptilian ____________ Birds have scales on __________ Differ greatly in body size, proportions, coloration, and capacity for flight Large durable _______ chambered heart The Rise of Mammals Mammals – A few aquatic mammals – Care for young for an extended period Adults serve as model for their behavior Behavioral Flexibility – Cerebral Cortex – Primates have most highly developed cerebral cortex Most mammals secure, cut and sometimes chew food before swallowing Dentition – Have 4 types of upper and lower teeth 1. 2. 3. 4. Teeth offer clues to life styles Portfolio of Existing Mammals 3 lineages of Mammals 1. Monotremes – 2. Marsupials – 3. Eutherians – Spiny anteaters and duck billed platypus are the only living monotremes Most marsupials are native to _______________ Newborns finish development in a permanent pouch on the mother Placenta – Grow faster in placenta then in marsupial pouch Primate Classification Order Primates – Prosimians dominated forests millions of years ago Anthropoids – Apes are closer to humans than monkeys in comparing biochemistry Hominids – Most are arboreal or tree dwellers 5 Trends helped to define lineage leading to humans 1. Less reliance on sense of smell and more on vision 2. Skeletal changes led to upright walking, which freed hands Bipedalism – 3. Changes in bones and muscles led to refined hand movements 4. Teeth became less specialized 5. Evolution of the brain, behavior and culture Parents put more effort in fewer offspring and formed stronger bonds From Early Primates to Hominids Origins and Early Divergences Primates evolved from _______________ more than 60 million years ago First ones resembled small _______________ Stayed in __________ because abundant food and safety Climate changed so they had to move out of the trees or die One lineage gave rise to great apes and other gave rise to the first hominids The First Hominids Australopiths – Australopiths has a large face, protruding jaws, small skull and brain Were apelike in many skeletal ways but humanlike in walking upright Australopithecus afarensis – Emergence of Early Humans The brain sets humans apart from apes Earliest humans – Homo habilis means ___________ __________ Homo erectus – means ____________ ____________ Clearly related to modern humans Traveled out of Africa to Europe, Asia More advanced tool maker Homo sapiens Means Evolved __________ years ago Developed complex language Neandertals Lived in ____________ 200,000 – 30,000 years ago Their disappearance coincided with the appearance of anatomically modern humans in the same regions about 40,000 – 30,000 years ago. We have no evidence that they interbred with the later arrivals Neandertal DNA has unique sequences, so they might not have contributed to the gene pools of modern European populations We still do not know what happened to them Humans spread rapidly through the world by devising cultural means to deal with a broader range of environments.
