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CS Chapter 24 Vocab
Chapter 24 Vocab
| Term | Definition |
|---|---|
| Invertebrate | Animal without a backbone; between 95 and 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 a 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 linning |
| 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 of 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 |
| Posterior | Tail end of an animal with bilateral symmetry |
| Cephalization | Tendency to concentrate 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 |
| Protostome | 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 small particles from water to get its food |
| Sessile | Organism permanently attached to one place |
| Cnidocytes | Nematocysts-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 take 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 |