Chapter 29: Vertebrates Flashcards
What four key traits define Chordates?
Notochord: Flexible rod providing skeletal support (replaced by vertebrae in most vertebrates).
Dorsal hollow nerve cord: Develops into the brain/spinal cord.
Pharyngeal slits: Openings in the pharynx (become gills in fish, ear/jaw structures in tetrapods).
Post-anal tail: Extends beyond the anus (reduced in humans).
Distinguish Urochordata (tunicates) and Cephalochordata (lancelets).
Urochordata: Larva has all chordate traits; adults lose most (e.g., sea squirts).
Cephalochordata: Retain all four traits as adults (e.g., lancelets filter-feed in sand).
What are the three major groups of fishes?
Agnatha (jawless fish): Hagfish (scavengers) and lampreys (parasites).
Chondrichthyes (cartilaginous fish): Sharks, rays (cartilage skeletons, electroreception).
Osteichthyes (bony fish): Ray-finned (e.g., tuna) and lobe-finned (e.g., coelacanth).
Describe lobe-finned fish and their evolutionary significance.
Fleshy fins with bone/muscle (e.g., coelacanth, lungfish).
Ancestors of tetrapods; Tiktaalik (transitional fossil) had limb-like fins and neck.
How do bony fish regulate buoyancy?
Swim bladder: Gas-filled organ adjusts buoyancy.
Operculum: Bony flap protecting gills.
What adaptations allowed amphibians to transition to land?
Lungs (supplemented by cutaneous respiration).
Stronger limbs (tetrapod locomotion).
Three-chambered heart (partial separation of oxygenated/deoxygenated blood).
Name the three orders of amphibians and examples.
Anura (frogs/toads): No tail (e.g., Rana).
Caudata (salamanders): Retain tail (e.g., axolotl).
Gymnophiona (caecilians): Legless, burrowing.
Why are amphibians considered environmental indicators?
Permeable skin absorbs pollutants; population declines signal ecosystem degradation.
What traits define amniotes?
Amniotic egg: Shell, chorion, amnion, yolk sac, allantois (prevents desiccation).
Dry, scaly skin (keratinized epidermis).
Thoracic breathing: Expand ribcage for lung inflation.
Compare Squamata, Testudines, and Crocodilia.
Squamata: Snakes/lizards (kinetic skulls, venom in some).
Testudines: Turtles/tortoises (bony shell fused to spine).
Crocodilia: Crocodiles/alligators (four-chambered heart, parental care).
How do reptiles regulate body temperature?
Ectotherms: Rely on external heat (sun basking).
What adaptations enable bird flight?
Feathers (contour for flight, down for insulation).
Hollow bones (reduce weight).
Endothermy (high metabolism for sustained energy).
Keeled sternum (anchor flight muscles).
Describe bird respiratory efficiency.
Air sacs: Unidirectional airflow through lungs (maximizes oxygen uptake).
What are ratites vs. carinates?
Ratites: Flightless (e.g., ostrich; flat sternum).
Carinates: Keeled sternum for flight (e.g., eagles).
Key mammalian traits.
Mammary glands (produce milk).
Hair/fur (keratin insulation).
Three middle ear bones (malleus, incus, stapes).
Neocortex (advanced brain region).
Compare monotremes, marsupials, and eutherians.
Monotremes: Egg-laying (e.g., platypus).
Marsupials: Pouch development (e.g., kangaroo).
Eutherians: Placental gestation (e.g., humans).
What is heterodont dentition?
Specialized teeth (incisors, canines, premolars, molars) for varied diets.
Primate adaptations for arboreal life.
Opposable thumbs/big toes (grasping).
Binocular vision (depth perception).
Large brains (complex social behavior).
Compare strepsirrhines and haplorhines.
Strepsirrhines: Wet-nosed (e.g., lemurs).
Haplorhines: Dry-nosed (tarsiers, monkeys, apes).
What distinguishes hominins from other primates?
Bipedalism (upright walking).
Reduced canine size.
Enlarged brain (tool use, language).
Key fossil hominins.
Australopithecus (e.g., Lucy): Bipedal, small brain.
Homo habilis: Early tool use.
Homo erectus: First to migrate out of Africa.
What is the significance of Tiktaalik?
Transitional fossil between fish and tetrapods; had fins with wrist bones and a neck.
How did the amniotic egg drive vertebrate diversification?
Enabled reproduction away from water → colonization of terrestrial habitats.
