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Flashcards in lecture 15 Deck (22):


-chordates clades were constructed by analysis of:
-molecular evidence
-anatomical evidence
-fossil evidence
-tunicates were thought to be the first group of chordates
-only chordates clade that does not have brain
-all other clades have a brain
-wide variation in brain sizes
-chordates that contains a head are referred to as craniates
-head consists of brain
-located at anterior end of the dorsal nerve cord
-contains a skull and all sensory organs
-eyes, ears, nose
-innovations allowed for active predation
-defined by the presence of an extensive, well defined backbone
-vertebral column
-composed of vertebrae
-functions to protect the contents of the nervous system


evolutionary tree chordates

-the next major evolutionary development was that of jaws
-followed by lungs and then muscular lobed fins with skeletal support
-tetrapods: jawed vertebrates with two pairs of limbs
-the first vertebrates on land
-amniotes: tetrapods with a terrestrially adapted egg
-this was the last major adaptation to life on land


hagfishes and lampreys

-most primitive chordates
-both are craniates
-both are jawless
-hagfish have a notochord
-strong flexible rod running the length of the fish body
-lamprey have a rudimentary vertebral column
-notochord also present
-classified as vertebrates because of VC



-approximately 40 species
-scavenge dead or nearly dead vertebrates
-along the bottom of the ocean
-almost blind
-excellent sense of smell and touch
-enter prey through existing holes
-or create holes using sharp structures on the tongue that resemble teeth
-they grasp and tear flesh
-excludes slime from glands on the sides of its body
-occurs when threatened
-after threat is removed the hagfish ties its tail in a knot and slides the knot forward to remove the layer of slime



-oldest living vertebrates
-suspension feeders
-live in freshwater streams
-most of the time in spent bried in sediment
-migration to the ocean or the sea
-occurs when they mature into adults
-most are parasitic
-attaches to the skin of prey using rasping tongue to penetrate
-fees on blood and tissues


jawed vertebrates

-appeared on fossil record 470 million years ago
-have paired fins and a tail
-allows them to swim to their prey
-jaws enable them to catch and eat a diverse group of prey
-contrast with suspension feeders
-jawed vertebrates with paired fins and gill are commonly referred to as fish
-initially skeletal rods supported the gill slits functioned to trap food particles
-two pairs of skeletal rods near the mouth have become the jaws and their supports
-three lineages:
-ray-finned fish
-lobe-finned fish



-sharks and rays
-flexible skeleton made of cartilage
-some sharks are suspension feeders
-eat small floating plankton
-most are predators
-quick swimmers with strong jaws
-sharp vision
-great sense of smell
-electrosensors on the head
-detect electromagnetic fields produced by muscles contractions of near by animals


sharks have lateral line systems

-a row of sensory organs that run along each side of the animal
-sensitive to changes in water pressure
-can detect very small vibrations caused by animals moving nearby


rays are adapted for life at the bottom of the ocean

-bodies are dorsoventrally flattened
-eyes on top of the head
-tail has sharp spines with venom glands at the base
-suspension feeders, swim through the ocean filtering plankton


ray-finned fish

-tuna. trout, and goldfish
-skeleton made of bone
-reinforced with cartilage
-hard matrix of calcium carbonate
-usually flattened scales over the skin
-secrete a mucus to reduce drag while swimming
-operculum: protective flap on each side of the head
-covers the chamber housing the gills
-movement of the operculum allows the fish to breathe without swimming
-contrast: sharks need to swim to pass water over their gills
-swim bladder: gas filled sac
-a lung derivative
-helps keep the fish buoyant
-evolved from balloon like lungs
-the largest group of vertebrates
-over 27,000 species


lobe-finned fish

-rod-shaped bones
-found in muscular, pectoral, and pelvic fins
-three lineages:
1. coelacanth: deep-sea dweller
2. lungfish: inhabit stagnant waters (water that doesnt flow)
-gulp air into lungs connected to the pharynx
3. tetrapods: adapted to life on land
-gave rise to terrestrial vertebrates



-salamanders and frogs
-verebrates with two pairs of limbs
-most are found in damp habitats
-moist skin supplements lungs for gas exchange
-skin usually has posion glands used in defense
-first vertebrae to colonize land
-distribution of most amphibians is limited because they require moisture because they are susceptible to dehydration
-some amphibians live only on land



-lizards, snakes, turtles and birds
-dinosaurs were reptiles
-major character that was derived here is the amniotic egg
-embryo develops inside enclosed by a protective fluid-filled sac called amnion
-allows reptiles to complete their life on land
-similar to the role of the seed in plant evolution
-snakes likely became limbless because their ancestors developed a burrowing lifestyle


other reptile adaptions

-reptilian skin: covered with scales, heavily keratinized to prevent drying out
-as a result reptiles may not breath through skin
-breath using a lung, assisted with a rib cage
-non-bird reptiles are referred to as cold-cold blooded
-do not use metabolism to generate body heat
-to stay warm they stay in the sun or maintain contact with warm surfaces
-absorbing heat rather than generating heat is referred to as actothermic
-previous reptiles such as dinosaurs are thought to have been endotherms
-dinosaurs are extinct today
-the reptilian group birds are descendante of one dinosaurs lineage



-evolved from theropods
-a small two legend group of dinosaurs
-suggested by fossil evidence
-feathers present on these dinosaurs
-not used for flight
-likely used for insulation and courtship displays
-archeaopteryx, the most primitive bird
-feathered wings
-otherwise more dinosaur like
-winged claws
-tail with lots of vertebrae


most features of he bird reflect adaptations that enhance flight

-reduce flight
-no teeth
-bones within the tail have only a few hollow vertebrae
-feathers have hollow shaft
-bones are honeycomb structure providing strength within a light-weight structure
-large breast muscles provide power for flight (white meat on turkey/chicken)


flying requires a great deal of energy

-high rate of metabolism
-endothermic feathers prevent heat loss
-very efficient circulatory system and lungs (more efficient at gas exchange than mammalian lungs)
-strong senses: amazing vision
-amniotic eggs: covered with hard shell



-Amniotes with hair and ability to produce milk
-fair functions to insulate
-mammals are endothermic
-mammary glands produce milk to nourish young
-differentiation of teeth allows consumption of many different foods
-larger brains than vertebrates of comparable size
-long period of parental care
-highly efficient circulatory and respiratory systems
-four chambered heart
-diaphragm assists in ventilation
-arose approx 200 million years ago
-probably nocturnal, small and insect eating


Three main groups of mammals




-duck-billed platypus
-only mammals that lay eggs
-female platypus usually lay two eggs
-incubates eggs in nest
-once born the babies lick milk from the mothers fur
-most mammals are born, not hatched
-embryos are nourished inside of the mothers body
-the lining of the uterus together with embryonic layers form a sac called a placenta which allows exchange of nutrients and wastes to and from the mothers body



-brief gestation
-mother gives birth to tiny offspring that complete embryonic development attached to the mothers nipples
-nourishing young are usually contained in an external pouch called a marsupium
-nearly all live in Australia, New Zealand and South America



-humans, zebras, elephants, rodents, and rabbits
-bear fully developed live young
-called placental mammals
-more complex than those of marsupials
-entire embryonic development is completed within the placenta