BIO 202 - Animal Biodiversity - Lecture 12

Flashcards about Phylum Chordata and Class Mammalia

Chordata

Animals with a notochord at some stage in their life cycle.

Craniata

Euchordates with a cranium; also known as Vertebrata.

Gnathostomata

Craniata with Jaws

Teleostomi

Bony fishes + tetrapods

Tetrapoda

Our limbed vertebrate y

Amniota

Tetrapods with embryos having extraembryonic membranes

Class Aves (the birds)

Animals with keratinized beak lacking teeth, feathers adapted for flight; evolution tied to flight; forelimbs modified into wings; modified bones; modified lungs; oviparous with parental care.

Origin of Birds

Descend from Archosaurian reptiles, Theropod dinosaurs (e.g. velociraptors) represent sister group of birds.

Archaeopteryx

Earliest known sister group of birds with feathers (147 mya).

Keratinized feathers

Beta-keratin; used for flight, contouring, insulation, waterproofing.

Skeletal modifications in birds related to flight

Pneumatized bones with struts, rigid airframe – fused vertebrae, sternum with large keel for flight muscles, muscles reduced in legs, mostly ligaments

Lung modification in Birds

Air passes across parabronchi; less “dead” volume.

Gut and excretory modifications in birds

Muscular crop and gizzard, use of sand for grinding food, very rapid digestion and elimination, more efficient kidney, concentrated uric acid, kidney empties into cloaca, salt glands allow drinking of seawater

Bird reproduction/ Anatomy differences

Females – only left ovary and oviduct develop. Males – most have lost penis – “cloacal kissing” except explosive, cork-screw penis in ducks and geese

Bird migration

Seasonal migration, same or different routes, nonstop or with rest stops; visual cues–coastline, rivers; sun by day, north star by night; earth’s magnetic field?

Class Mammalia (the mammals)

Animals with hair and mammary glands.

Hair in Mammals

Hair made mostly of keratin (alpha-keratin), common to all mammals (even marine), many functions (warmth, tactile, defense)

Integument glands in mammals

Sweat glands (for cooling and scent) & sebaceous glands (oil for skin and hair.

Mammary glands

Modified sweat glands; fully develop in mature females to give milk during lactation; no nipples in monotremes

Mammalian Teeth Modification

Incisors, canines, molars; diphyodont – 2 sets of teeth: deciduous (milk), permanent.

Horns vs Antlers

Keratin over skull bone vs annual bone growth and loss

Adaptations for Herbivory in Mammals

Molars for grinding, multiple stomachs with microbial symbionts, multiple passages through gut

Mammalian Reproduction

Dioecious; internal fertilization; most with specific breeding season; female fertility restricted to periods of estrus.

Monotremes reproduction

Oviparous with platypus eggs in a burrow, echidnas in pouch

Marsupials reproduction

Viviparous with short gestation; tiny newborns must attach to nipple in pouch

Placentals (eutherians) reproduction

Viviparous with placenta; long gestation in uterus with nourishment from placenta; developmental status at birth varies widely: precocial vs. atricial

Descent of Homo sapiens

Arboreal to ground dwelling, Homininae (great apes) 8 mya, genus Homo 2 mya, bipedalism, grasping hands, opposable thumb, complex social behaviors, tool use (in chimps also)

Homeothermy in Mammals

High metabolic rate, insulation by fur, feathers or fat, vasoconstriction, countercurrent heat exchange in appendages

Evolutionary trends in vertebrates

Vertebrates evolved from aquatic to terrestrial existence; key adaptations include: jaws, lungs, limbs, amniotic egg, homeothermy

Amniotic Egg Parts

Amnion (fluid filled sac around embryo), chorion (gas exchange), yolk