Biology Concepts and Connections 7e - Biology Chapter 18: The Evolution of Invertebrate Diversity
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| 1529619531 | ingestion | The act of eating; the first main stage of food processing in animals. | 0 | |
| 1529619532 | blastula | An embryonic stage that marks the end of cleavage during animal development; a hollow ball of cells in many species. | 1 | |
| 1529619533 | gastrula | The embryonic stage resulting from gastrulation in animal development. Most animals have a gastrula made up of three layers of cells: ectoderm, endoderm, and mesoderm. | 2 | |
| 1529619534 | ectoderm | The outer layer of three embryonic cell layers in a gastrula; forms the skin of the gastrula and gives rise to the epidermis and nervous system in the adult. | 3 | |
| 1529619535 | mesoderm | The middle layer of the three embryonic cell layers in a gastrula. It gives rise to muscles, bones, the dermis of the skin, and most other organs in the adult. | 4 | |
| 1529619536 | larva | (plural, larvae) A free-living, sexually immature form in some animal life cycles that may differ from the adult in morphology, nutrition, and habitat. | 5 | |
| 1529619537 | metamorphosis | The transformation of a larva into an adult. | 6 | |
| 1529619538 | invertebrate | An animal that lacks a backbone. | 7 | |
| 1529619539 | radial symmetry | An arrangement of the body parts of an organism like pieces of a pie around an imaginary central axis. Any slice passing longitudinally through a radially symmetrical organism's central axis divides it into mirror-image halves. | 8 | |
| 1529619540 | bilateral symmetry | An arrangement of body parts such that an organism can be divided equally by a single cut passing longitudinally through it. A bilaterally symmetrical organism has mirror-image right and left sides. | 9 | |
| 1529619541 | anterior | Pertaining to the front, or head, of a bilaterally symmetrical animal. | 10 | |
| 1529619542 | posterior | Pertaining to the rear, or tail, of a bilaterally symmetrical animal. | 11 | |
| 1529619543 | dorsal | Pertaining to the back of a bilaterally symmetrical animal. | 12 | |
| 1529619544 | ventral | Pertaining to the underside, or bottom, of a bilaterally symmetrical animal. | 13 | |
| 1529619545 | body cavity | A fluid-containing space between the digestive tract and the body wall. | 14 | |
| 1529619546 | hydrostatic skeleton | A skeletal system composed of fluid held under pressure in a closed body compartment; the main skeleton of most cnidarians, flatworms, nematodes, and annelids. | 15 | |
| 1529619547 | true coelom | A body cavity completely lined with tissue derived from mesoderm. | 16 | |
| 1529619548 | psuedocoelom | A body cavity that is not lined with mesoderm and is in direct contact with the wall of the digestive tract. | 17 | |
| 1529619549 | protostome | An animal with a coelom that develops from solid masses of cells that arise between the digestive tube and the body wall of the embryo. The protostomes include the molluscs, annelids, and arthropods. | 18 | |
| 1529619550 | deuterostomes | An animal with a coelom that forms from hollow outgrowths of the digestive tube of the early embryo. The deuterostomes include the echinoderms and the chordates. | 19 | |
| 1529619551 | eumetazoan | Member of the clade of "true animals," the animals with true tissues (all animals except sponges). | 20 | |
| 1529619552 | bilaterian | Member of the clade of animals Bilateria exhibiting bilateral symmetry. | 21 | |
| 1529619553 | sponge | An aquatic animal characterized by a highly porous body. | 22 | |
| 1529619554 | choancyte | A flagellated feeding cell found in sponges. Also called a collar cell, it has a collar-like ring that traps food particles around the base of its flagellum. | 23 | |
| 1529619555 | amoebocyte | An amoeba-like cell that moves by pseudopodia, found in most animals; depending on the species, may digest and distribute food, dispose of wastes, form skeletal fibers, fight infections, and change into other cell types. | 24 | |
| 1529619556 | suspension feeder | An aquatic animal that sifts small food particles from the water. | 25 | |
| 1529619557 | sessile | An organism that is anchored to its substrate. | 26 | |
| 1529619558 | cnidarian | An animal characterized by cnidocytes, radial symmetry, a gastrovascular cavity, and a polyp and medusa body form. Cnidarians include the hydras, jellyfishes, sea anemones, corals, and related animals. | 27 | |
| 1529619559 | polyp | One of two types of cnidarian body forms; a columnar, hydra-like body. | 28 | |
| 1529619560 | medusa | One of two types of cnidarian body forms; an umbrella-like body form. | 29 | |
| 1529619561 | gastrovascular cavity | A digestive compartment with a single opening, the mouth; may function in circulation, body support, waste disposal, and gas exchange, as well as digestion. | 30 | |
| 1529619562 | cnidocyte | A specialized cell for which the phylum Cnidaria is named; consists of a capsule containing a fine coiled thread, which, when discharged, functions in defense and prey capture. | 31 | |
| 1529619563 | flatworm | A member of the phylum Platyhelminthes. | 32 | |
| 1529619564 | free-living flatworms | One of a group of nonparasitic flatworms. | 33 | |
| 1529619565 | flukes | One of a group of parasitic flatworms. | 34 | |
| 1529619566 | tapeworms | A parasitic flatworm characterized by the absence of a digestive tract. | 35 | |
| 1529619567 | nematode | A roundworm, characterized by a pseudocoelom, a cylindrical, wormlike body form, and a tough cuticle. | 36 | |
| 1529619568 | cuticle | (1) In animals, a tough, nonliving outer layer of the skin. (2) In plants, a waxy coating on the surface of stems and leaves that helps retain water. | 37 | |
| 1529619569 | complete digestive tract | A digestive tube with two openings, a mouth and an anus. | 38 | |
| 1529619570 | molluscs | A soft-bodied animal characterized by a muscular foot, mantle, mantle cavity, and radula; includes gastropods (snails and slugs), bivalves (clams, oysters, and scallops), and cephalopods (squids and octopuses). | 39 | |
| 1529619571 | foot | In an invertebrate animal, a structure used for locomotion or attachment, such as the muscular organ extending from the ventral side of a mollusc. | 40 | |
| 1529619572 | visceral mass | One of the three main parts of a mollusc, containing most of the internal organs. | 41 | |
| 1529619573 | mantle | In a mollusk, the outgrowth of the body surface that drapes over the animal. The mantle produces the shell and forms the mantle cavity. | 42 | |
| 1529619574 | radula | A toothed, rasping organ used to scrape up or shred food; found in many molluscs. | 43 | |
| 1529619575 | circulatory system | The organ system that transports materials such as nutrients, O2, and hormones to body cells and transports CO2 and other wastes from body cells. | 44 | |
| 1529619576 | gastropod | A member of the largest group of molluscs, including snails and slugs. | 45 | |
| 1529619577 | bivalve | A member of a group of molluscs that includes clams, mussels, scallops, and oysters. | 46 | |
| 1529619578 | cephalopods | A member of a group of molluscs that includes squids and octopuses. | 47 | |
| 1529619579 | segmentation | Subdivision along the length of an animal body into a series of repeated parts called segments. | 48 | |
| 1529619580 | annelid | A segmented worm. Annelids include earthworms, polychaetes, and leeches. | 49 | |
| 1529619581 | open circulatory system | A circulatory system in which blood is pumped through open-ended vessels and bathes the tissues and organs directly. In an animal with an open circulatory system, blood and interstitial fluid are one and the same. | 50 | |
| 1529619582 | closed circulatory system | A circulatory system in which blood is confined to vessels and is kept separate from the interstitial fluid. | 51 | |
| 1529619583 | polychaetes | A member of the largest group of annelids. | 52 | |
| 1529619584 | arthropod | A member of the most diverse phylum in the animal kingdom. Arthropods include the horseshoe crab, arachnids (for example, spiders, ticks, scorpions, and mites), crustaceans (for example, crayfish, lobsters, crabs, and barnacles), millipedes, centipedes, and insects. Arthropods are characterized by a chitinous exoskeleton, molting, jointed appendages, and a body formed of distinct groups of segments. | 53 | |
| 1529619585 | exoskeleton | A hard, external skeleton that protects an animal and provides points of attachment for muscles. | 54 | |
| 1529619586 | molting | The process of shedding an old exoskeleton or cuticle and secreting a new, larger one. | 55 | |
| 1529619587 | horseshoe crab | A bottom-dwelling marine chelicerate, a member of the phylum Arthropoda. | 56 | |
| 1529619588 | chelicerate | A lineage of arthropods that includes horseshoes crabs, scorpions, ticks, and spiders. | 57 | |
| 1529619589 | arachnid | A member of a major arthropod group (chelicerates) that includes spiders, scorpions, ticks, and mites. | 58 | |
| 1529619590 | millipede | A terrestrial arthropod that has two pairs of short legs for each of its numerous body segments and that eats decaying plant matter. | 59 | |
| 1529619591 | centipedes | A carnivorous terrestrial arthropod that has one pair of long legs for each of its numerous body segments, with the front pair modified as poison claws. | 60 | |
| 1529619592 | crustacean | A member of a major arthropod group that includes lobsters, crayfish, crabs, shrimps, and barnacles. | 61 | |
| 1529619593 | complete metamorphosis | A type of development in certain insects in which development from larva to adult is achieved by multiple molts that are followed by a pupal stage. While encased in its pupa, the body rebuilds from clusters of embryonic cells that have been held in reserve. The adult emerges from the pupa. | 62 | |
| 1529619594 | incomplete metamorphosis | A type of development in certain insects in which development from larva to adult is achieved by multiple molts, but without forming a pupa. | 63 | |
| 1529619595 | echinoderm | Member of a phylum of slow-moving or sessile marine animals characterized by a rough or spiny skin, a water vascular system, an endoskeleton, and radial symmetry in adults. Echinoderms include sea stars, sea urchins, and sand dollars. | 64 | |
| 1529619596 | endoskeleton | A hard skeleton located within the soft tissues of an animal; includes spicules of sponges, the hard plates of echinoderms, and the cartilage and bony skeletons of vertebrates. | 65 | |
| 1529619597 | water vascular system | In echinoderms, a radially arranged system of water-filled canals that branch into extensions called tube feet. The system provides movement and circulates water, facilitating gas exchange and waste disposal. | 66 | |
| 1529619598 | dorsal, hollow nerve cord | One of the four hallmarks of chordates, a tube that forms on the dorsal side of the body, above the notochord. | 67 | |
| 1529619599 | notochord | A flexible, cartilage-like, longitudinal rod located between the digestive tract and nerve cord in chordate animals; present only in embryos in many species. | 68 | |
| 1529619600 | pharyngeal gill slits | A gill structure in the pharynx; found in chordate embryos and some adult chordates. | 69 | |
| 1529619601 | post-anal tail | A tail posterior to the anus; found in chordate embryos and most adult chordates. | 70 | |
| 1529619602 | tunicate | One of a group of invertebrate chordates. | 71 | |
| 1529619603 | lancelet | One of a group of invertebrate chordates. | 72 |
