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Chapter 24 vocab


Invertebrate Animal without a backbone; between 95-99 percent of animal species are invertebrates.
Exoskeleton Hard or tough outer covering of many invertebrates that provides support, protects body tissues, prevents water loss, and protects the organism from predation.
Endoskeleton INternal skeleton that protects internal organs, provides support for the organism's body, and can provide an internal brace for muscles to pull against.
Vertebrate Animal with an endoskeleton and a backbone.
Hermaphrodite Animal that produces both sperm and eggs in its body, generally at different times.
Zygote Fertilized egg formed when as sperm cell penetrates an egg.
Internal Fertilization Type of fertilization that occurs when sperm and egg combine inside an animal's body.
External Fertilization Type of fertilization that occurs when sperm and egg combine outside an animal's body.
Blastula Fluid-filled ball of cells formed by mitotic cell division of the embryo.
Gastrula Two-cell-layer sac with an opening at one end that forms from the blastula during embryonic development.
Endoderm Inner layer of cells in the gastrula that develops into digestive organs and the digestive tract lining.
Ectoderm Outer layer of cells in the gastrula that develops into nervous tissue and skin.
Mesoderm Layer of cells between the endoderm and the ectoderm that can become muscle tissue and tissue of the circulatory, respiratory, and excretory systems.
Symmetry Balance or similarity in body structures of organisms.
Radial Symmetry Body plan that can be divided along any plane, through a central axis, into roughly equal halves.
Bilateral symmetry Body plan that can be divided into mirror images along only one plane through the central axis.
Anterior Head end of an animal with bilateral symmetry.
Cephalization Tendency to concentrates sensory organs and nervous tissue at an animal's anterior end.
Dorsal Backside of an animal with bilateral symmetry.
Ventral Underside or belly of an animal with bilateral symmetry.
Coelom Fluid-filled body cavity completely surrounded by mesoderm.
Pseudocoelom Fluid-filled body cavity between the mesoderm and the endoderm.
Acoelomate Animal with a solid body that lacks a fluid-filled body cavity between the gut and the body wall.
Prostosome Coelomate animal whose mouth develops from the opening in the gastrula.
Deuterostome Coelomate animal whose anus develops from the opening in the gastrula.
Filter Feeder Organism that filters smalls particles from water to get its food.
Sessile Organism permanently attached to one place.
Cnidocytes Nematocyst-containing stinging cell on a cnidarian's tentacle.
Nematocyst Capsule whose threadlike tube contains poison and barbs and is discharged when prey touches a cnidarian.
Gastrovascular Cavity In cnidarians, the space surrounded by an inner cell, layer where digestion takes place.
Nerve Net Cnidarian nervous system that conducts impulses to and from all parts of the body.
Polyp Tube-shaped, sessile body form of cnidarians.
Medusa Umbrella-shaped, free swimming body form of cnidarians.
Created by: Jsmith3