Animal Diversity and Function

Four key characteristics of chordates

Dorsal hollow nerve cord, notochord, pharyngeal slits, post-anal tail.

Notochord function

Cartilage rod that becomes disks in the backbone.

Lancelets and tunicates

Invertebrate chordates that are ancestors to all vertebrates.

Hagfishes and lampreys

Most primitive vertebrates; lack hinged jaws and paired fins.

Operculum function in ray-finned fishes

Protective gill flap that allows breathing without swimming.

Swim bladder function

Air-filled sac that keeps bony fish neutrally buoyant.

First tetrapods to colonize land

Amphibians.

Amniotes

Tetrapods with a terrestrially adapted egg (reptiles, birds, mammals).

Three main groups of mammals

Monotremes (egg-laying), marsupials (pouched), and eutherians (placental).

Primate arboreal adaptations

Limber joints, grasping hands, and forward-pointing eyes for depth perception.

Origin of Homo sapiens

Africa, with oldest fossils discovered in Ethiopia.

Birds as flying reptiles

Modern feathered reptiles that evolved from theropod dinosaurs.

Endotherm vs. ectotherm

Endotherms regulate body heat internally; ectotherms absorb heat from the environment.

Mammalian characteristics

Hair/fur and mammary glands producing milk.

Hominin evolution trend

Bipedalism evolved long before large brain sizes.

Chondrichthyes

Cartilaginous fishes like sharks and rays with skeletons made of cartilage instead of bone.

Lateral line system

A system of sense organs in aquatic vertebrates used to detect movement and vibration in water.

Amphibian metamorphosis

The biological process where aquatic larvae transform into terrestrial adults.

Marsupial development

Mammals that give birth to underdeveloped young and complete development in an external pouch.

Placental mammals (Eutherians)

Mammals where young complete embryonic development within the uterus connected by a placenta.

Avian adaptations for flight

Hollow bones, feathers, a keeled sternum, and a highly efficient respiratory system.