Body Plan: the set of morphological and development traits that define a grade (level of organizational complexity).
Radial Symmetry: characterizing a body-shaped like a pie or barrel with many eqaul parts radiating outward like the spokes of a wheel; present in cnidarians and echindoerms; also can refer to flower structure.
Bilateral Symmetry: characterizing a body form with a central longitudinal plane that divides the body into two eqaul parts but opposite halves.
Dorsal: pertaining to the back of a bilaterally symmetrical animal.
Ventral: pertaining to teh underside, or bottom, of a bilaterally symmetrical animal.
Anterior: the head end of a bilaterally symmetrical animal.
Posterior: rear, or tail end, of a bilaterally symmetrical animal.
Cephalization: An evolutionary trend toward the concentration of sensory equipment on the anterior end of the body.
Germ Layers: three main layers that form the various tissues and organs of an animal body.
Endoderm: inmost of the three main layers in animal embryos; lines the archenteron and gives rise to the liver, pancreas, lungs, and the lining of the digestive tract.
Diploblastic: having two germ layers.
Triplobalstic: three germ layers, the endodoerm, meso0derm, and ectoderm.
Mesoderm: the middle priamry germ layer of an early embryo tht develops into the notochord, the lining of the coelom, muscles, skeleton, gonads, kidneys, and most of the circulatory system.
Body Cavity: a fluid-containing space between the digestive tract and the body wall.
Coelom: a body cavity completely lined with mesoderm.
Pseudocoelomate: an animal whose body cavity is not completely lined by mesoderm.
Coelomate: animal that possesses a true coelom (fluid- filled body cavity lined by tissue completely derived from mesoderm).
Acoelomate: a solid-bodied animal lacking a cavity between the gut and outer body wall.
Ventral side of a star fish
The three Germ Layers
The Body Caivty
Radial and Bilateral Symmetry
- Example: sponges
- Characterisitics: no true tissue, suspension feeders
-Example: corals, jelltfish, and hydra
-Characteristics: gastrovascular cavity, mouth and anus
-Characterisitics: microscopic size, organ systems, alimentry canal, feed on micororganisms
- Characteristics: segemted worms
-Examples: flatworms, tapeworms, and flukes
-Examples: insects, crustaceans, and arachnids
- Characterisitics: segemnted exoskeleton, jointed appendages
-Examples: snails, clams, squids, and octupuses
- Charaterisitics: soft body, hard shell
-Examples: sand dollars, sea stars, and sea urchins
- Charactersitics: radial symmetry, internal canals
- Charactersitics: tough cucticle, tubular
Review Quiz Questions:
1. Acoelomates are characterized by...?
-a. the absence of a brain
-b. the absence of mesoderm
-c. deuterostome development
-d. a coelom that is not completely lined with mesoderm
-e. a solid bodt without a cavity surrounding internal organs
2. Which of the following subdivisions of the animal kingdom encompases all the other in the list...?
3. A land snail, a clam, and an octupus all share...?
-a. a amntle
-b. a radula
-d. embryonic torsion
-e. distinct cephalization
1. e, 2. d, 3. a
Created By Alyssa Hamilton