Animal Biology - Invertebrates and Behavior

Flashcards for key terms and definitions related to animal biology, covering invertebrates and animal behavior.

Invertebrates

Animals that do not have backbones.

Exoskeleton

A hard or tough outer covering that provides support to an organism.

Endoskeleton

A skeleton located inside an organism that provides support.

Vertebrates

Animals that possess a backbone and an endoskeleton.

Hermaphrodites

Organisms that produce both eggs and sperm in the same body.

Zygote

A structure formed when a sperm penetrates an egg.

Internal fertilization

Fertilization that occurs inside an animal’s body.

External fertilization

Fertilization that occurs outside an animal's body.

Blastula

A fluid-filled ball of cells formed in the early stages of development.

Gastrula

A two-layer sac with an opening at one end, formed during early development.

Endoderm

The inner layer of cells in the gastrula that develop into digestive organs.

Ectoderm

The outer layer of cells in the gastrula that develop into nervous tissue and skin.

Mesoderm

The layer of cells that forms between the endoderm and ectoderm.

Symmetry

Describes the balance or similarity among body structures of organisms.

Radial symmetry

Body symmetry where an organism can be divided along any plane through a central axis.

Bilateral symmetry

Body symmetry where an organism can be divided along one plane through a central axis.

Cephalization

The concentration of nervous tissue and sensory organs at the anterior end of an animal.

Coelom

A fluid-filled body cavity formed from mesoderm that encloses the organs.

Pseudocoelom

A fluid-filled body cavity developing between the endoderm and mesoderm.

Protostomes

Organisms where the mouth develops from the first opening in the gastrula.

Deuterostomes

Organisms where the anus develops from the first opening in the gastrula.

Chordates

Deuterostomes belonging to the phylum Chordata, characterized by having a notochord.

Dorsal tubular nerve cord

A cord located above the digestive organs, shaped like a tube.

Notochord

A flexible, rod-like structure that extends along the length of the body in chordates.

Postanal tail

A body structure used mainly for locomotion extending beyond the anus.

Cnidocytes

Stinging cells found in cnidarians.

Nematocysts

Capsules within cnidocytes containing poison and a coiled thread.

Hydrostatic skeleton

A fluid-filled cavity providing rigid support for muscles in some animals.

Amnion

The membrane surrounding an embryo as it develops.

Amniotic egg

A developing structure with a protective shell and membranes containing fluids.

Innate behavior

Behavior that is genetic-based and not learned.

Learned behavior

Behavior that results from the interaction of innate behaviors and experiences.

Agonistic behavior

Threatening or combative behavior between individuals of the same species.

Dominance hierarchies

A social structure where top-ranked animals have access to resources.

Foraging behaviors

Behavior involving finding, hunting, and eating food.

Circadian rhythm

A daily cycle of sleeping and waking.