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Clip Shape of Life: Chordata Different classes, which include jawless fishes (e.g., lampreys), cartilaginous fishes (e.g., sharks), bony fishes, amphibians, reptiles, birds, and mammals. Major Characteristics Dorsal, hollow nerve cord Pharyngeal pouches -Spinal cord -in neck or throat region -Nerves branch off and Tail that extends connect to organs & muscles beyond the anus Notochord - at some point in their lives -Supporting rod that lies just Animation below the nerve cord Adult Derivatives of Pharyngeal Pouches Pouch Adult derivatives 1 Lining of auditory tube and tympanic cavity (middle ear cavity) 2 Largely obliterated, lining of intratonsillar cleft (tonsilar fossa) 3 Inferior parathyroid glands, thymus 4 Superior parathyroid glands, parafollicular cells of thyroid gland Dealing with the environment *temperature *salinity 1. Ectotherms – Thermoregulation Regulating body temperature Obtain body heat from the environment 2. Endotherms – – – – Homeotherm Generate own body heat- metabolism High energy requirement Birds and mammals able to invade colder areas 3. Poikillotherm – – Variable body temperature Most aquatic animals (excluding sea mammals)- body temp is same as surrounding H2O Thermostat: hypothalamus Four physical processes account for heat gain or loss • • • • conduction. convection. evaporation. radiation. Evaporation and convection are the most variable causes of heat loss. Thermoregulation involves physiological and behavioral adjustments that balance heat gain and loss: 1. Adjusting rate of heat exchange between animal and its surroundings -Alter amount of blood flowing between body core and skin -vasoconstriction and vasodilation -altering diameter of blood vessels -countercurrent heat exchange in extremities 2. Cooling by evaporative heat loss – panting or sweating vasodilation vasoconstriction Thermoregulation involves physiological and behavioral adjustments that balance heat gain and loss: 3.Behavioral responses – basking in sun, migration, hibernation 4. Changing the rate of metabolic heat production – only in mammals and birds; heat produced instead of ATP (nonshivering thermogenesis); brown fat, blubber, insulation Endothermy (Homeothermy) • Only birds and mammals • Expensive – Human – 60% of nutritional intakes goes to providing heat. – Metabolic rate of mammals is 10x that of a reptile. • Homotherms were able to invade colder environments. Temperature conservation can became a problem as animals moved onto land. Animals can maintain somewhat constant body temp by… – Snake warms itself in the sun and cools off by hiding in the shade (Ectotherms) – Bees swarm in a hive to raise the temperature – Dogs pant – Elephants flap their ears – Humans shiver Countercurrent Exchange • The opposite flow of adjacent fluids that maximizes transfer rates – Heat exchange, gas exchange – Ex: • Fish use countercurrent exchanges to maximize the extraction of oxygen from water across the membrane of their gills. • Bird legs in water, fish tails Water has about 10,000x less O2 than air. Countercurrent heat exchangers Gills Gas exchange at the gill surface is enhanced by the opposing flows of water and blood at the gills. Countercurrent Exchange -blood flows opposite to the direction in which H2O passes over gills, maintaining a constant concentration gradient for O2 between the blood and the H2O passing over the gill surface Fish: Countercurrent Also involved in osmoregulation Osmoregulation Management of the body’s water solute concentration • Marine vertebrates – ocean is hypertonic • H2O constantly lost by osmosis – They produce little urine & drink large amts of seawater. – Extra salt is actively transported out through the gills. • Freshwater fish – Water is hypotonic • H2O constantly diffuses in by osmosis – Rarely drink – Constantly urinate – Absorb salt through gills Osmoregulation • Terrestrial organisms – Must rid themselves of waste but still retain water Nonvertebrate Chordates • Two groups do NOT have backbones: 1. Tunicates: -filter feeders, larval form has chordate characteristics, adults do not 2. Lancelets: -small, fish-like, live on sandy ocean bottom Tunicates Lancelet tunicate lancelet Most Chordates are Vertebrates Key Features •A vertebrate is an animal with a strong, flexible backbone. •All vertebrates exhibit bilateral symmetry and a true body cavity with an endoskeleton. •Found in aquatic and terrestrial environments. Key Features Endoskeleton: •Support •Attachment for muscles •Grows with the animal Fishes • Aquatic vertebrates that have: • paired fins – movement • scales – protection • gills – respiration (gas exchange) *there are exceptions to all of these because fish are SO varied 3 classes: 1. Agnatha (Gnathostomulida) -- jawless 2. Chondrichthyes – cartilage skeleton 3. Osteichthyes – bony fish Major Characteristics: •Lateral Line System •Row of sensitive cells that can detect very small amounts of motion in the water. •Closed circulatory system •Well developed nervous system and brain •Exchange gases using gills- diffusion •Herbivores, carnivores, parasites, filter feeders, and Detritivores. •Movement- contracting muscles on either side of the backbone •Excreation-NH3 or NH4+ 2 chambered heart simplest type of true heart • One atrium and one ventricle – Atrium- chambers that receive blood – Ventricles-chamber that pump blood out. • Blood flow to the tissues and back to the heart is aided by swimming motions. • Blood travels from the heart to the gills, and then directly to the body before returning Temperature • Most aquatic animals (excluding sea mammals) are poikilotherms. – having variable body temperature • Maintain a body temp by seeking a region in the ocean of optimal temp and remaining there. • Their metabolic processes do generate heat, but it is quickly dissipates into the surrounding water. Skeleton made of fibers and cartilage Hagfish Lack eyes- detect light through sensors on their body Feed on dead and dying fish Soft skin devoid of scales •Lampreys •Usually parasites External fertilization. Oviparous ( egg laying) •Two chambered heart •Gills used for respiration •No external ears •No eye lids •Have funnel-like mouths lined with sharp teeth. •In center of mouth is tongue with a tooth like projection. •Attaches to other fish by suction. It tears a hole in the fish and injects a chemical that keeps the blood from clotting. Sucks blood and fluids from its host. Vertebrate jaws evolved from skeletal supports of the pharyngeal slits Most sharks are carnivorous • Prey may be swallowed whole or pieces may be torn from large prey. – Teeth evolved as modified scales. – The digestive tract is proportionately shorter than in other vertebrates. • A spiral valve, which increases surface area and slows food movement, is present in the intestine. •Sharks and Rays •Complete vertebral column, movable jaws, and skeleton with paired fins. •All of these structures are made up of cartilage •Whale shark can grow up to 49.5 ft weighing 39,600 pounds. • Sharks have streamlined bodies and are swift swimmers. – The tail provides propulsion. – The dorsal fins serve as stabilizers. – Pectoral and pelvic fins produce lift. •Some buoyancy is provided by large amounts of oil stored in liver, but most must swim continuously to remain in the water column. •Continual swimming also produces water flow through mouth and over gills for gas exchange. –Some sharks are known to rest on the sea floor and in caves; they use jaw and pharynx muscles to pump water over their gills while resting. •Water enters the mouth and water passes over the gills where the gases are exchanged. •Sharp sense of smell. •Also have lateral line system. •Internal fertilization Internal fertilization -Ovoviviparous • A pair of claspers on the pelvic fins of males transfers sperm into the female reproductive tract. • Some species are oviparous, some are ovoviviparous, and a few are viviparous. Viviparous-The embryo develops INSIDE the mother and the mother gives a live birth. Like people. Oviparous-animals that lay eggs, with little or no other embryonic development within the mother. Like chickens. Ovoviviparous-animals develop within eggs that remain within the mother's body up until they hatch or are about to hatch. Like fish. Bony endoskeleton, operculum, & swim bladder Most abundant and diverse Skeleton made of bone Marine & freshwater Swim Bladder: thin sac that acts as a float. (Filled with gasses) Can be adjusted so that the fish can move to different levels. Lateral line system and a keen sense of smell. Most-external fertilization No external ears No eye lids. 1. Gills for gas exchange • gas exchange is more difficult for aquatic animals with gills than for terrestrial animals with lungs because water is denser than air and contains less O2 per unit volume 2. Two chambered heart • only vertebrates in which blood flows directly from respiratory organs to body tissues without first returning to the heart • Gas exchange occurs by drawing water over the four or five pairs of gills located in chambers covered by an operculum. – Water is drawn into the mouth, through the pharynx and out between the gills by movement of the operculum and contraction of muscles within the gill chambers. • Allows bony fishes to breath while stationary. mudskippers Adaptations in Vertebrates for life on land Endothermy Strong Limbs Lungs Skin Muscles Eggs ~365 mya Amphibian Basics Clip Major Characteristics: •Lives in water as a larvae and on land as an adult •Moist skin •Breathes with lungs as an adult •Lacks scales and claws •Must return to water to reproduce. •Age of amphibians: 360-286 mya Orders of Amphibians • Order Urodela – salamanders & newts *long bodies and tails, 4 legs *moist/wet areas • Order Anura – frogs and toads *all can jump *frogs more closely tied to water than toads • Order Apoda – caecilians *least known *legless *live in water or burrow in moist soil *some have fish-like scales in their skin Success on Land: Lungs, stronger bones in limbs to help support weight out of water, breastbone to protect internal organs. First vertebrates to adapt to life on land Young can only live in water Undergo metamorphosis and can live on land Tadpole stage can regenerate lost parts •Smooth skin, no scales, feet are webbed, toes are soft and lack claws •no external ears: have eardrums or tympanic membranes Eggs usually laid in water and fertilized externally Amphibian eggs lack a shell & dehydrate quickly in dry air. In some species, males or females may house eggs on their back, in the mouth, or even in the stomach Feeding, respiration, circulation, excretion, response, movement, reproduction • Feeding: tadpoles are filter feeders or herbivores; frogs are carnivores *have stomach, small intestines, large intestines, cloaca • Respiration: • *tadpoles have gills; adults have lungs and use their thin, moist skin (moist surface of mouth). Excretion: uric acid -kidneys filter wastes from blood, make urine which is stored in bladder until can be released Circulation: – 3 chambered heart • 2 atria, 1 ventricle • double-loop circulation – oxygenated and deoxygenated blood mix in the one ventricle Feeding, respiration, circulation, excretion, response, movement, reproduction • Response: *well developed nervous systems, specialized sections of brain *good eyesight *hear with tympanic membrane – transmits vibrations •Movement: body *tadpoles swim – tail for propulsion *adult amphibians walk or jump – legs at sides of Feeding, respiration, circulation, excretion, response, movement, reproduction Reproduction: *use external fertilization *Oviparous – lay eggs *Reproductive posture is called amplexus Ecology •Food for other animals •Some can produce poison defense Blue Poison Frog • Amphibians: In Cold Blood (Sir David Attenborough ) Video Turtles, crocodilians, Lizards, and Snakes ~300 mya In Cold Blood Clip Major Characteristics: •Dry, scaly skin •Scales made of keratin Helps prevent water loss With scales or plates Reptiles: Major Chara. Clip Major Characteristics: •Lungs Able to breath air •Terrestrial eggs with several membranes (Oviparous) internal fertilization Development of amniotic egg • Oviparous: animals that lay eggs • One of the most important adaptations for life on land. • Does not need water for reproduction Development of amniotic egg: egg covered w/a shell that protects the developing embryo from drying out Excretion: uric acid • Some species of lizards and snakes are viviparous, their extraembryonic membranes forming a placenta that enables the embryo to obtain nutrients from its mother. Egg Layers All turtles All tortoises All crocodilians Some lizards Iguanas Water dragons Geckos Veiled chameleons Panther chameleons Monitors Snakes All pythons Kingsnakes Milksnakes Rat snakes Corn snakes Livebearers Some lizards Solomon Island skink Blue-tongue skink Shingle-backed skink Some chameleons Jackson's chameleon Some snakes All boas All vipers Garter snakes Limbs, if present, having toes with claws used for climbing, digging, and moving around on land. Ectotherm: animals with a body temperature that is influenced by the environment *Due to ectothermy, reptiles can survive on less than 10% of the calories required by mammals of comparable size. *uses behavioral adaptations to absorb solar energy and regulate its body temperature. Snakes • Jacobson's organ • Flicking tongue helps transmit odors toward olfactory organs on roof of mouth. • Most reptiles have a threechambered heart; although, the ventricle is partially divided. – The partially divided ventricle reduces mixing of oxygenated and deoxygenated blood. Intro to Birds Clip Strong Chests muscles •Only group adapted to life in the air. •Body covered with feathers •Modified scales •Made of the protein keratin and develop in pit in the birds’ skin. •Two types: Contour (Lift) & Down (Warmth) •Help birds fly and keep warm •Attract mate •In some species-waterproof Clip The bones have a honeycombed internal structure that provides strength while reducing weight Birds have the following adaptations to flight Wings which are Homologous to front limbs in other vertebrates Tutor Vista Clip: Birds Feathers Strong chest muscles that also that power Provide warmth Upward and downward wing strokes Efficient respiratory system Efficient circulatory system that provide that ensure One-way flow of O2-rich air O2 distribution to body tissues Air Flow animati on Endotherms: A constant warm temp. generated internally by a high metabolic rate. •Birds have higher metabolic rate than mammals •Two legs covered with scales •Modified for specific useperching, walking, etc. •Front limbs modified into wings. Molting: birds sheds their feathers at least once a year (gradual) Thin hollow bones -Toothless beak •Birds have many different types of feet and beaks. Modified for the life style of the bird. Reproduction: •Internal fertilization •Amniotic eggharder shells than reptiles Digestion: Crop: Storage Gizzard: Can contain small stones, help with the mechanical breakdown of food Feeding, respiration, circulation, excretion, response, movement, reproduction • Lungs – but have specialized air sacs and breathing tubes that pull air in when inhale and make sure that oxygenated air is always in the lungs – air only moves in one direction, so yields high metabolic rate (provides energy, and allows birds to breath at high altitudes) The respiratory system of a bird more efficient than the human respiratory system because the bird’s respiratory system does not mix exhaled air with inhaled air- air only moves in one direction Feeding, respiration, circulation, excretion, response, movement, reproduction • Response: well-developed sense organs (great senses of sight and hearing); advanced brain to interpret and respond during headlong flight • Movement: flight, walk, run, swimming *bones are light and filled with a scaffolding support Feeding, respiration, circulation, excretion, response, movement, reproduction • Circulation: four chambered heart, double loop circulation, that segregates oxygenated blood from unoxygenated blood. – The complete separation of oxygenated and deoxygenated blood increases the efficiency of oxygen delivery to the cells. • Excretion: nitrogen waste removed from blood by kidneys, secreted as uric acid crystals (white, pasty droppings, little water) – uric acid =Allows water conservation Birds also have a very well developed nervous system. • Acute vision and well-developed visual and coordinating areas of the brain aid in flying. • They show complex behavior especially during breeding season when elaborate courtship rituals are performed. Feeding, respiration, circulation, excretion, response, movement, reproduction • Reproduction: separate sexes, internal fertilization, amniotic eggs *some parent birds can produce and regurgitate a substance from the crop that is rich in protein and fat to feed offspring – “bird milk”; this is actually just sloughed-off cells from their crop mixed with saliva and mucus The Anatomy of a Pigeon 1 When a bird eats, food moves down the esophagus and is stored in the crop. Brain Esophagus Crop Lung Heart Kidney Air sac 2 Moistened food passes to the stomach, a twoLiver part chamber. The first chamber secretes acid and First chamber of stomach enzymes. The partially Gizzard Small digested food moves intestine to the second chamber, the gizzard. 3 The muscular walls of the gizzard squeeze 4 As digestion the contents, continues, while small the food moves stones grind the through food. the intestines. Pancreas Large intestine Cloaca 5 Undigested food is excreted through the cloaca. Cassowary Rheas There are many species of flightless birds: ostrich, penguins Emus Ecology Pollination Seed dispersal Control insect populations Indicator of environmental health Rachel Carson‘s book Silent Spring - pesticides in the food chain Humans, Manatees, Elephants, Kangaroos, Apes, Tigers, Dogs Major Characteristics •Body covered with hair made of keratin-provides insulation •Young nourished in the uterus •Young nourished w/milk from mammary glands •lung-breathing throughout lifetime Intro to mammals Clip •Differentiated teeth •Large brains-capable of learning Major Characteristics •Endothermic •Subcutaneous fat under skin to conserve heat •Sweat glands to cool body Feeding: •Carnivores, herbivores, and omnivores. •Evolution of a strong more powerful jaw enabled mammals to eat food other than insects. Reproduction: •Internal fertilization Placental (Eutherian) mammals: Live birth Monotremes:Egg-laying mammals: platypuses and echidnas -After hatching, young suck milk from the fur of the mother who lacks nipples. Marsupials:Pouched mammals: Kangaroo, koalas, opossum **Young are born in an early stage of development and completes its development while nursing. Australian monotremes and marsupials: echidna (top left), marsupial mouse (lower left), sugar glider (right) Monotremes:Egg-laying mammals • Excretion-Urea – less toxic than NH3 and requires less H2O – NH3 converted to urea in liver • Kidneys filter blood, add water to make urine. Form and Function of Mammals • Jaws and teeth allow for diverse diet • Highly developed brains with good senses – taste, sight (color vision), smell, hearing (ears with chambers), touch • Movement varied: run, walk, climb, burrow, hop, pounce, swing, fly, leap, and swim Circulation • Double-loop circulation, 4 chambered heart • two atria and two ventricles • deoxygenated and oxygenated bloods are not mixed Pig