Chapter 18 Flashcards
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.
Amoebocyte
A segmented worm. These organisms include earthworms, polychaetes, and leeches.
Annelid
Pertaining to the front, or head, of a bilaterally symmetrical animal.
Anterior
A member of a major arthropod group (chelicerates) that includes spiders, scorpions, ticks, and mites.
Arachnid
A member of the most diverse phylum in the animal kingdom. These members are characterized by a chitinous exoskeleton, molting, jointed appendages, and a body formed of distinct groups of segments.
Anthropod
An arrangement of body parts such that an organism can be divided equally by a single cut passing longitudinally through it. This organism has mirror-image right and left sides.
Bilateral Symmetry
Member of the clade of animals Bilateria exhibiting bilateral symmetry.
Bilaterian
A member of a group of molluscs that includes clams, mussels, scallops, and oysters.
Bivalve
An embryonic stage that marks the end of cleavage during animal development; a hollow ball of cells in many species.
Blastula
A fluid-containing space between the digestive tract and the body wall.
Body Cavity
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.
Centipede
A member of a group of molluscs that includes squids and octopuses.
Cephalopod
The transformation of a larva into an adult.
Metamorphosis
A terrestrial arthropod that has two pairs of short legs for each of its numerous body segments and that eats decaying plant matter.
Millipede
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).
Molluscs
The process of shedding an old exoskeleton or cuticle and secreting a new, larger one.
Molting
A roundworm, characterized by a pseudocoelom, a cylindrical, wormlike body form, and a tough cuticle.
Mematode
A flexible, cartilage-like, longitudinal rod located between the digestive tract and nerve cord in chordate animals; present only in embryos in many species.
Notochord
system in which blood is pumped through open-ended
vessels and bathes the tissues and organs directly. In an animal with this system, blood and interstitial fluid are one and the same.
Open Circulatory System
Structures found in the pharynx; found in chordate embryos and some adult chordates.
Pharyngeal Gill Slits
A member of the largest group of annelids.
Polychaetes
One of 2 types of cnidarian body forms; a columnar body, hydra like body.
Polyp
A tail posterior to the anus; found in chordate embryos and most adult chordates.
Post anal tail
Pertaining to the rear, or tail, of a bilaterally symmetrical animal.
Posterior
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. These animals include the molluscs, annelids, and arthropods.
Protostomes
A body cavity that is in direct contact with the wall of the digestive tract.
Pseuodocoelom
An arrangement of the body parts of an organism like pieces of a pie around an imaginary central axis. Any slice passing longitudinally along the organism’s central axis divides it into mirror-image halves.
Radial Symmetry
A toothed, rasping organ used to scrape up or shred food; found in many molluscs.
Radula
Subdivision along the length of an animal body into a series of repeated parts called segments.
Segmentation
An organism that is anchored to its substrate.
Sessil
An aquatic animal characterized by a highly porous body.
Sponge
An aquatic animal that sifts small food particles from the water.
Suspension Feeder
A parasitic flatworm characterized by the absence of a digestive tract.
Tapeworms
One of a group of invertebrate chordates.
Tunicates
Pertaining to the underside, or bottom, of a bilaterally symmetrical animal.
Ventral
One of the three main parts of a mollusc, containing most of the internal organs.
Visceral Mass
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.
Water Vascular System
