Condensed Animal Biology and Evolutionary Innovations

Vocabulary practice flashcards covering animal classifications, structural features, and major evolutionary innovations from Bilateria to Mammals and Sauropsids.

Animals

Multicellular heterotrophs characterized by an extracellular matrix containing collagen.

Bilateria

A major animal clade characterized by bilateral symmetry and three germ layers.

Protostomes

A major developmental group of animals in which the blastopore develops into the mouth.

Deuterostomes

A major developmental group of animals in which the blastopore develops into the anus.

Ecdysis

The process of molting, or shedding the outer cuticle as an animal grows.

Ecdysozoa

A clade of protostome animals characterized by molting (ecdysis); includes Nematoda and Arthropoda.

Nematoda

A phylum of Ecdysozoa consisting of roundworms that possess a cuticle and undergo molting.

Arthropoda

A phylum of Ecdysozoa characterized by segmentation, jointed appendages, a chitinous exoskeleton, and molting.

Chelicerata

A major group of arthropods that includes spiders, scorpions, and ticks.

Crustacea

A major group of arthropods that includes crabs, shrimp, and lobsters.

Myriapoda

A major group of arthropods that includes centipedes and millipedes.

Hexapoda

A major group of arthropods that includes insects.

Lophotrochozoa

A clade of protostome animals that includes Mollusca, Annelida, and Platyhelminthes.

Mollusca

A phylum of Lophotrochozoa defined by a body plan consisting of a mantle, a muscular foot, and a visceral mass.

Bivalvia

A major group of mollusks that includes clams, mussels, and oysters.

Gastropoda

A major group of mollusks that includes snails and slugs.

Cephalopoda

A major group of mollusks that includes squid, octopus, and cuttlefish.

Annelida

A phylum of Lophotrochozoa characterized by segmentation; includes earthworms, leeches, and polychaete worms.

Platyhelminthes

A phylum of Lophotrochozoa consisting of flatworms with a flat body; includes planarians, flukes, and tapeworms.

Echinodermata

A deuterostome phylum featuring a water vascular system and tube feet, displaying bilateral symmetry as larvae and radial symmetry as adults.

Water Vascular System

A system in echinoderms that uses water pressure to operate tube feet for movement, feeding, and attachment.

Notochord

A flexible supporting rod found in chordates.

Dorsal Hollow Nerve Cord

A chordate structure running along the back that develops into the brain and spinal cord in vertebrates.

Pharyngeal Slits

Throat-region structures present in chordates, associated with gills in fish.

Muscular Post-Anal Tail

A muscular tail structure extending beyond the anus, present in chordates at some developmental stage.

Endostyle / Thyroid Gland

A chordate structure involved in processing iodine.

Cephalochordates

A chordate lineage consisting of small fish-like animals, such as lancelets, that retain chordate traits.

Urochordates

A chordate lineage including tunicates (sea squirts) whose larvae display chordate traits while adults look very different.

Vertebrates

A chordate lineage characterized by a vertebral column that replaces or supports the notochord.

Gnathostomes

Jawed vertebrates, an evolutionary innovation that permitted better feeding and access to more food types.

Osteichthyans

Bony vertebrates characterized by a bony skeleton.

Actinopterygii

Ray-finned fish whose fins are supported by rays; includes most familiar fish.

Sarcopterygii

Lobe-finned fish characterized by fleshy, muscular fins from which tetrapods evolved.

Tetrapoda

Animals characterized by four limbs (limbs with digits) or descended from ancestors with four limbs.

Amphibians

Tetrapods including frogs, salamanders, and caecilians that remain closely tied to water for reproduction due to unprotective eggs.

Amniotic Egg

An evolutionary innovation in amniotes that protects the embryo, allowing reproduction on land away from water.

Amnion

The protective egg structure that surrounds and protects the embryo.

Chorion

The structure of an amniotic egg responsible for gas exchange.

Allantois

The structure of an amniotic egg responsible for waste storage.

Yolk Sac

The structure of an amniotic egg that provides nutrients/food to the developing embryo.

Synapsids

The amniote lineage that includes mammals.

Sauropsids

The amniote lineage that includes reptiles and birds.

Mammals

Synapsid amniotes whose key identifying traits are hair and mammary glands.

Monotremes

A group of mammals that lay eggs, such as the platypus.

Marsupials

Mammals whose young undergo short internal development followed by further development after birth, such as kangaroos.

Placental Mammals

Mammals characterized by longer internal development supported by a placenta, such as humans, dogs, and whales.

Birds

Sauropsid reptiles whose primary distinguishing traits are feathers, wings, and a lightweight skeleton.