Campbell Biology, Chapter 34: Vertebrates

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Chordates
Bilaterian animals; belong to clade Deuterostomia; have muscular, post-anal tail, dorsal, hollow nerve cord, notochord, pharyngeal slits/clefts, mouth, anus, and muscular segments
Notochord
Longitudinal, flexible rod located between the digestive tube and the nerve cord. Composed of large fluid-filled cells encased in fairly stiff fibrous tissue. Provides fibrous support body. Reduced in humans.
Dorsal, hollow nerve cord
Nerve cord dorsal to notochord. Hollow. Unique to chordates, other animal phyla have ventrally-located solid cords. Develops into central nervous system.
Pharyngeal slits/clefts
Develop from grooves along the sides of the pharynx. Function as suspension feeding devices in many invertebrates. In vertebrates, have been modified for gas exchange and are known as gill slits. In tetrapods, do not develop into slits, but help develop ear structures and head/neck.
Post-anal tail
Greatly reduced during embryonic development. Nonchordates have a digestive tract that extends nearly the whole length of the body.
Lancelets
Part of cephalochordata. The most basal group of living chordates. Eat via cilia trappings. Have chevron-like muscle arrangement. Relatively rare in global environment.
Tunicates
Part of urochordata. Most closely related to other chordates than our lancelets. Most apparent during larval stage. Adult stage draws water through incurrent siphon-->atrium-->excurrent siphon. Mucus net captures food then transported by cilia to esophagus. Anus empties into excurrent siphon.
Craniates
Chordates w/ head-- brain @ anterior end of dorsal nerve. Has eyes and other sensory organs, as well as skull. Have a heart with at least 2 chambers, blood with hemoglobin, kidneys that remove waste products in blood.
Neural crest
Collection of cells appearing near dorsal margins of closing neural tube in an embryo. Disperse throughout body to give rise to teeth, bone and cartilage, inner layer of facial skin.
Hagfishes
Most basal groups of craniates. Part of myxini Have skull made of cartilage. Lack jaws and vertebrae. Have segmented muscles, flex against notochord (which is retained in adulthood). Small brain, eyes, and ears. Their mouth has tube-like formations made of keratin. Most are bottom-dwelling scavengers. Emit slime.
Vertebrates
Craniates with backbone (composed of vertebrae, enclose spinal chord and have mechanical role of notochord). During Cambrian period, lineage of craniates gave rise to vertebrates w/ more complex nervous system and better skeleton. More efficient gas exchange system in gills.
Lampreys
Petromyzontida-- most basal lineage of vertebrates. Marine and freshwater, most are parasitic. Use tongue to drink fish blood. Skeleton made of cartilage w/ no collagen. Have sheath over notochord w/ cartilage projections similar to vertebrae. Have partially enclosed nerve cord.
Conodonts
Slender, soft-bodied vertebrates w/ prominent eyes. Lived from late Cambrian until late Triassic. Had mineralized mouthparts, which was used for either predation or scavenging.
Gnasthosomes
Jawed vertebrates. Includees sharks and their relatives, ray-finned fishes, lobe-finned fishes, amphibians, reptiles (including birds), and mammals.
Lateral line system
Organs in aquatic gnasthosomes that are sensitive to vibrations in the surrounding water.
Placoderms
Armored vertebrates. Appeared roughly 450 million years ago.
Acanthodians
Groups of jawed vertebrates emerged around 450 million years ago, radiated 450-420 million years ago. Diverged into chondrichthyans, ray-finned fishes, and lobe-fins.
Chondrichthyans
Include sharks, rays, and their relatives. Skeleton made up primarily of cartilage, although often impregnated with calcium.
Oviparous
Some species of sharks lay eggs that hatch outside of the mother's body. Eggs released after being encased in protective coats.
Ovovivparous
Retention of the fertilized eggs in the oviduct in some species of shark. Nourished by egg yolk. Embryos develop into young that are born after hatching w/in the uterus.
Viviparous
Young develop w/in uterus, obtain nourishment from mother's blood from yolk sac placenta, absorb nutritious fluid produced by uterus, or eat other eggs.
Cloaca
Reproductive tract, excretory system, and digestive tract empty into this. Has single opening to outside.
Ostheichthyans
Have ossified (bony) endoskeleton with hard matrix of calcium phosphate.
Operculum
Protective bony flap covering 4 or 5 pairs of fish gills.
Swim bladder
Air sac; the way fishes can control their buoyancy. Mvmt of gases from the blood to swim bladder increases buoyancy, transfer back to blood causes sinking.
Ray-finned fishes
Have bony rays that support fins. Originated 444-416 million years ago. Major source of protein for humans.
Lobe-fins
Have rod-shaped bones surrounded by a thick layer of muscle in pectoral and pelvic fins. Includes coelacanths, lungfishes, and another lineage that gave rise to tetrapods.
Tetrapods
Gnasthosomes with limbs. Have 4 limbs with digits. Originated ~365 million years ago when fins of lobe-fins evolved limbs with digits. Also have a neck, a pelvic girdle, and a lack of gill slits.
Tiktaalik
"Fishapod"-- had full sets of ribs (breathing and body support), neck and shoulders, and basic bone pattern of all limbed animals in front fin. Stands as the vertebrate transition from water to land.
Amphibians
Includes salamanders, frogs, and caecilians. Some live both a terrestrial and aquatic life. External fertilization occurs in most, and eggs are laid in moist environments.
Paedomorphism
Retaining juvenile features in its adult stage. Common amongst salamanders.
Amniotes
Group of tetrapods whose extant members are the reptiles (including birds) and mammals. Have egg with amnion, chorion, yolk sac, and allantois.
Amniotic Egg
Has 4 specialized membranes: the amnion (protects embryo in a fluid-filled cavity), the chorion (exchange gas between the embryo and air), the yolk sac (contains nutrients, which are transported by blood vessels), and the allantois (disposal sac and respiratory organ). Has calcareous shell.
Reptile
Clade including Tuataras, lizards, snakes, turtles, crocodilians, and birds. Have scales made of keratin. Fertilization is internal. Often ectothermic.
Ectothermic
Absorbing external heat as the main source of body heat in the organism. Excludes birds.
Endothermic
Capable of maintaining body temperature through metabolic activity.
Parareptiles
Large, stock, quadrupedal herbivores. Some had plated skin. Arose during the late Carboniferous and died out by the end of Triassic (~200 million years ago).
Diapsids
Have a pair of holes on each sides of the skull, behind the eye socket. Muscles pass through these holes to control jaw movement. Composed of 2 main lineages: lepidosaurs and archosaurs.
Lepidosaurs
Includes tuataras, lizards, and snakes, and marine reptiles.
Archosaurs
Crocodilians, pterosaurs, and dinosaurs.
Pterosaurs
First tetrapods to exhibit flapping flight. Different wing than that of birds and bat. Fossil evidence suggests they had adjustable membranes to assist in flight.
Dinosaurs
Could be bipedal or quadrapedal. Included herbivorous ornithischians, long-necked saurischians, and theropods (bipedal carnivores).
Theropods
Bipedal carnivorous dinosaurs. Included Tyrannosaurus rex and the ancestor of birds.
Turtles
Reptiles with a boxlike shell made of upper and lower shields fused to vertebrae, have clavicles (collarbones), and ribs.
Ratites
Flightless birds, includes strich, rhea, kiwi, cassowary, and emu. Have relatively small pectoral muscles (which is why penguins are not included).
Mammals
Other amniote lineage that is not repitles. More than 5000 species. Have mammary glands, which produce milk for offspring. Have hair, fat layer under the skin, and are endothermic. Have a high metabolic rate. Belong to a group of amniotes called synapsids.
Synapsids
Have single temporal fenestra= hole behind behind eye socket on each side of skull, where jaw muscles pass through and anchor on the temple.
Monotremes
Found only in Australia and New Guinea, represented by one species of platypus and four species of echidnas (spiny anteaters). Lay eggs.
Marsupials
Opossums, kangaroos, and koalas. Higher metabolic rates and nipples that provide milk. Give birth to live young nourished by placenta. Babies are born very early in development; complete while nursing in marsupium (pouch).
Placenta
Structure made by lining of uterus and extraembryonic membranes. Provides nourishment for growing embryos.
Eutherians
Placental mammals-- placenta more complex than those of marsupials. Have longer pregnancy than marsupials. Includes primates (3 main groups).
Opposable thumb
Thumb that is relatively movable and separate from the fingers, can touch the fingerprint side of all four fingers in same hand.
Anthropoids
Monkeys and apes found worldwide.
Homo sapiens
Human species, arose ~200,000 years ago. New in evolutionary history. Have much larger brains than apes, stand upright and are bipedal, capable of language, symbolic thought, artistic expression, and using tools.
Paleoanthropology
Study of human origins