BIO2 CH32

Animals

Multicellular, heterotrophic eukaryotes that ingest food and have specialized tissues

Heterotroph

An organism that obtains energy by consuming other organisms

Ingestion

Taking food into the body for internal digestion

Collagen

Structural protein in animals that supports cells (instead of cell walls)

Tissues

Groups of similar cells that perform a specific function

Muscle tissue

Tissue that enables movement in animals

Nervous tissue

Tissue that allows animals to respond to stimuli

Cleavage

Rapid cell division without growth after fertilization

Blastula

Hollow ball of cells formed during early embryonic development

Gastrulation

Process where the blastula forms layers of embryonic tissues

Gastrula

Embryo with distinct germ layers

Ectoderm

Outer germ layer that forms skin and nervous system

Endoderm

Inner germ layer that forms digestive tract lining

Mesoderm

Middle germ layer that forms muscles and internal organs

Hox genes

Regulatory genes that control body structure and organization

Larva

Immature stage of an animal that differs from the adult form

Metamorphosis

Transformation from larval stage to adult form

Choanoflagellates

Protists that are the closest living relatives of animals

Multicellularity

Condition of having many cells that cooperate and specialize

Cell adhesion

Ability of cells to stick together

Cell signaling

Communication between cells

Ediacaran biota

Earliest known macroscopic animal fossils (~560 million years ago)

Cambrian explosion

Period of rapid diversification of animal life (~535–525 million years ago)

Predation

Interaction where one organism consumes another

Bilaterians

Animals with bilateral symmetry, a complete digestive tract, and three germ layers

Paleozoic era

Era marked by diversification of animals and colonization of land

Mesozoic era

Era dominated by reptiles and dinosaurs

Cenozoic era

Era of mammal diversification and modern ecosystems

Body plan

Set of structural and developmental traits of an organism

Symmetry

Arrangement of body parts around an axis

Radial symmetry

Body parts arranged around a central axis

Bilateral symmetry

Body has left and right halves

Cephalization

Concentration of sensory organs and brain at the head

Diploblastic

Animals with two germ layers (ectoderm and endoderm)

Triploblastic

Animals with three germ layers (ectoderm, mesoderm, endoderm)

Body cavity

Fluid-filled space between digestive tract and body wall

Coelom

True body cavity completely lined by mesoderm

Acoelomate

Animal lacking a body cavity

Hemocoel

Body cavity filled with hemolymph

Hemolymph

Circulatory fluid in animals with a hemocoel

Protostome

Animal whose blastopore develops into the mouth

Deuterostome

Animal whose blastopore develops into the anus

Spiral cleavage

Diagonal cell division pattern in protostomes

Radial cleavage

Parallel or perpendicular cell division in deuterostomes

Determinate cleavage

Early cells have fixed developmental fate

Indeterminate cleavage

Early cells can develop into a complete organism

Blastopore

Opening in the gastrula that becomes mouth or anus

Archenteron

Primitive gut formed during gastrulation

Coelom formation (protostome)

Forms by splitting of mesoderm

Coelom formation (deuterostome)

Forms from outpocketing of archenteron

Phylogeny

Evolutionary history and relationships among organisms

Porifera

Sponges; lack true tissues and are the earliest animals

Eumetazoa

Animals with true tissues

Bilateria

Animals with bilateral symmetry and three germ layers

Invertebrates

Animals without a backbone

Vertebrates

Animals with a backbone

Deuterostomia

Clade including echinoderms and chordates

Ecdysozoa

Clade of animals that molt an exoskeleton

Ecdysis

Shedding of an exoskeleton

Lophotrochozoa

Clade with lophophore or trochophore larva

Lophophore

Feeding structure with ciliated tentacles

Trochophore larva

Free-swimming larval stage in some animals

Exoskeleton

External skeleton that supports and protects the body

Molt

Shedding of outer covering for growth

Common ancestor

Shared origin of all animals

Systematics

Study of evolutionary relationships and classification