Biology: Chapter 9 - Animal Evolution, Diversity, and Behavior

vertebrate

animal that has a backbone

chordate

animal that has, for at least one stage of its life, a dorsal, hollow nerve cord; a notochord; a tail that extends beyond the anus; and pharyngeal pouches

invertebrate

animal that lacks a backbone, or vertebral column

coelom

body cavity lined with mesoderm

bilateral symmetry

body plan in which a single imaginary line can divide the body into left and right sides that are mirror images of each other

radial symmetry

body plan in which any number of imaginary planes drawn through the center of the body could divide it into equal halves

cephalization

concentration of sense organs and nerve cells at the anterior end of an animal

zygote

fertilized egg

hominoid

group of anthropoids that include gibbons, orangutans, gorillas, chimpanzees, and humans

society

group of closely related animals of the same species that work together for the benefit of the group

behavior

manner in which an organism reacts to changes in its internal condition or external environment

communication

passing information from one organism to another

feedback inhibition

process in which a stimulus produces a response that opposes the original stimulus; also called negative feedback

language

system of communication that combines sounds, symbols, and gestures according to a set of rules about sequence and meaning, such as grammar and syntax

bipedal

the ability to walk upright

kin selection

theory that states that helping relatives can improve an individual's evolutionary fitness because related individuals share a large portion of their genes

opposable thumb

thumb that enables the grasping of objects and the utilization of tools

cartilage

type of connective tissue that supports the body; is softer and more flexible than bone

tetrapod

vertebrate with four limbs