Honors Biology: Animals

animal

Multicellular, heterotrophic, eukaryotic organisms whose cells lack cell walls

invertebrate

Animal that lacks a backbone or vertebral column

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

notochord

Long supporting rod that runs through a chordate's body just below the nerve cord

radial symmetry

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

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

endoderm

Innermost germ layer; develops into the linings of the digestive tract and much of the respiratory system

mesoderm

Middle germ layer; develops into muscles, and much of the circulatory, reproductive, and excretory systems

ectoderm

Outermost germ layer; produces sense organs, nerves, and outer layer of skin

coelom

Body cavity lined with mesoderm

pseudocoelom

Body cavity, which is only partially lined with mesoderm

acoelomate

Absence of or without a body cavity; lack a coelom between the body wall and digestive cavity

segmentation

Body is divided into numerous repeated parts or segments

blastula

A hollow ball of cells that develops when a zygote undergoes a series of cell divisions

protostome

An animal whose mouth is formed from the blastopore

deuterstome

An animal whose anus is formed from the blastopore, and the mouth is formed from a second opening that develops

cephalization

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

intracellular digestion

Type of digestion in which food is digested in specialized cells that pass nutrients to other cells by diffusion

extracellular digestion

Type of digestion in which food is broken down outside the cells in a digestive system and then absorbed

gastrovascular cavity

Digestive chamber with a single opening

digestive tract

Tube that begins at the mouth and ends at the anus

alveoli

Tiny air sacs at the end of a bronchiole in the lungs that provide surface area for gas exchange to occur

open circulatory system

Type of circulatory system in which blood in only partially contained within a system of blood vessels as it travels through the body

closed circulatory system

Type of circulatory system in which blood circulates entirely within blood vessels that enters throughout the body

excretion

Process by which metabolic wastes are eliminated from the body

nephridia

Excretory structure of an annelid that filter body fluid

Malphigian tubules

Structure in most terrestrial arthropods that concentrates the uric acid and adds it to digestive wastes

neuron

Nerve cell; specialized for carrying messages throughout the nervous system

stimulus

Signal to which an organisms responds

response

Specific reaction to a stimulus

ganlgia

A group of interneurons

cerebrum

Part of the brain responsible for voluntary activities of the body; "thinking" region of the brain

cerebellum

Part of the brain that coordinates movement and controls balance

hydrostatic skeleton

Skeleton made of fluid-filled body segments that work with muscles to allow the animal to move

water vascular system

A hydraulic system composed of canals connecting numerous tube feet used by echinoderms for locomotion, food and waste transportation, and respiration

exoskeleton

External skeleton; tough external covering that protects the body of many invertebrates

endoskeleton

Internal skeleton; structural support system within the body of an animal

metamorphosis

Process of changes in shape and form of larva into an adult

amniotic egg

Egg composed of shell and membranes that creates a protected environment in which the embryo can develop out of water

homeostasis

Relatively constant internal physical and chemical conditions that organisms maintain

endotherm

Animal whose body temperature is regulated, at least in part, using heat generates within the body

ectotherm

Animal whose body temperature is determined but the temperature of its environment

mammal

Animals that have mammary glands that produce milk in females to nourish young, body hair, and breathe air, have a four-chambered heart, and regulate their internal body temperature