Biology, animals, chapter 25
Terms
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- annelid
- An invertebrate; a segmented worm (e.g., oligochaete, leech, or polychaete).
- arthropod
- Invertebrate with hard exoskeleton, specialized segments, and jointed appendages.
- bilateral symmetry
- Body plan with axis from anterior to posterior end, separated into right and left sides, and dorsal and ventral surface.
- cephalization
- Over time, the concentration of sensory structures and nerve cells in a head.
- cnidarian
- Type of radial invertebrate at the tissue level of organization; the only nematocyst producer.
- coelom
- A peritoneum-lined cavity between the gut and body wall of most animals.
- collar cell
- In sponge body wall, a flagellated cell
- cuticle
- Of annelids, a thin, flexible coat. Of arthropods, a lightweight exoskeleton hardened with protein and chitin.
- deuterostome
- Bilateral animal in which the anus forms from first indentation in the embryo (e.g., echinoderms, chordates).
- echinoderm
- Type of invertebrate with calcified spines, needles, or plates on body wall. Radial with some bilateral features (e.g., sea stars).
- ectoderm
- The first-formed, outermost primary tissue layer of animal embryos; gives rise to nervous system tissues and integument's outer layer
- endoderm
- Inner primary tissue layer of animal embryos; source of inner gut lining and derived organs.
- exoskeleton
- External skeleton (e.g., hardened cuticle of arthropods).
- flatworm
- One of the simplest invertebrates having organ systems; a turbellarian, fluke, or tapeworm. Some are notorious parasites.
- gut
- Generally, a sac or tube from which food is absorbed into internal environment. Also, gastrointestinal tract from stomach onward.
- hermaphrodite
- Individual having both male and female gonads.
- invertebrate
- Any animal without a backbone.
- larva
- Immature stage between an embryo and adult in many animal life cycles.
- medusa
- Of cnidarian life cycles, a freeswimming, bell-shaped stage, often with oral lobes and tentacles extending below the bell.
- metamorphosis
- Major changes in body form of certain animals; hormonally controlled growth, tissue reorganization, and remodeling of body parts leads to adult form.
- mollusk
- Only invertebrate with mantle draped over a soft, fleshy body; most have an external or internal shell. Diverse body plans and sizes (e.g., gastropods, bivalves, and cephalopods).
- molting
- Periodic shedding of worn-out or too small body structures. Permits some animals to grow in size or renew parts.
- nematocyst
- Cnidarian capsule that has a dischargeable, tube-shaped thread, sometimes barbed; releases a toxin or sticky substance.
- protostome
- Lineage of coelomate, bilateral animals that includes mollusks, annelids, and arthropods. The first indentation to form in protostome embryos becomes the mouth.
- radial symmetry
- Animal body plan having four or more roughly equivalent parts around a central axis (e.g., sea anemone).
- roundworm
- Cylindrical, bilateral, cephalized animal with a false coelom and a complete digestive system. Most cycle nutrients in communities; many are parasites.
- sponge
- Animal with no body symmetry, and no tissues, and phagocytic collar cells in its body wall. Lineage dates from precambrian.
- vertebrate
- Animal having a backbone.
- water-vascular system
- Of sea stars and sea urchins, a system of many tube feet that are deployed in synchrony for smooth locomotion.