Chapter 18

Question 0

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.

Answer 0

Amoebocyte

Question 1

A segmented worm. These organisms include earthworms, polychaetes, and leeches.

Answer 1

Annelid

Question 2

Pertaining to the front, or head, of a bilaterally symmetrical animal.

Answer 2

Anterior

Question 3

A member of a major arthropod group (chelicerates) that includes spiders, scorpions, ticks, and mites.

Answer 3

Arachnid

Question 4

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.

Answer 4

Anthropod

Question 5

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.

Answer 5

Bilateral Symmetry

Question 6

Member of the clade of animals Bilateria exhibiting bilateral symmetry.

Answer 6

Bilaterian

Question 7

A member of a group of molluscs that includes clams, mussels, scallops, and oysters.

Answer 7

Bivalve

Question 8

An embryonic stage that marks the end of cleavage during animal development; a hollow ball of cells in many species.

Answer 8

Blastula

Question 9

A fluid-containing space between the digestive tract and the body wall.

Answer 9

Body Cavity

Question 10

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.

Answer 10

Centipede

Question 11

A member of a group of molluscs that includes squids and octopuses.

Answer 11

Cephalopod

Question 12

The transformation of a larva into an adult.

Answer 12

Metamorphosis

Question 13

A terrestrial arthropod that has two pairs of short legs for each of its numerous body segments and that eats decaying plant matter.

Answer 13

Millipede

Question 14

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).

Answer 14

Molluscs

Question 15

The process of shedding an old exoskeleton or cuticle and secreting a new, larger one.

Answer 15

Molting

Question 16

A roundworm, characterized by a pseudocoelom, a cylindrical, wormlike body form, and a tough cuticle.

Answer 16

Mematode

Question 17

A flexible, cartilage-like, longitudinal rod located between the digestive tract and nerve cord in chordate animals; present only in embryos in many species.

Answer 17

Notochord

Question 18

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.

Answer 18

Open Circulatory System

Question 19

Structures found in the pharynx; found in chordate embryos and some adult chordates.

Answer 19

Pharyngeal Gill Slits

Question 20

A member of the largest group of annelids.

Answer 20

Polychaetes

Question 21

One of 2 types of cnidarian body forms; a columnar body, hydra like body.

Answer 21

Polyp

Question 22

A tail posterior to the anus; found in chordate embryos and most adult chordates.

Answer 22

Post anal tail

Question 23

Pertaining to the rear, or tail, of a bilaterally symmetrical animal.

Answer 23

Posterior

Question 24

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.

Answer 24

Protostomes

Question 25

A body cavity that is in direct contact with the wall of the digestive tract.

Answer 25

Pseuodocoelom

Question 26

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.

Answer 26

Radial Symmetry

Question 27

A toothed, rasping organ used to scrape up or shred food; found in many molluscs.

Answer 27

Radula

Question 28

Subdivision along the length of an animal body into a series of repeated parts called segments.

Answer 28

Segmentation

Question 29

An organism that is anchored to its substrate.

Answer 29

Sessil

Question 30

An aquatic animal characterized by a highly porous body.

Answer 30

Sponge

Question 31

An aquatic animal that sifts small food particles from the water.

Answer 31

Suspension Feeder

Question 32

A parasitic flatworm characterized by the absence of a digestive tract.

Answer 32

Tapeworms

Question 33

One of a group of invertebrate chordates.

Answer 33

Tunicates

Question 34

Pertaining to the underside, or bottom, of a bilaterally symmetrical animal.

Answer 34

Ventral

Question 35

One of the three main parts of a mollusc, containing most of the internal organs.

Answer 35

Visceral Mass

Question 36

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.

Answer 36

Water Vascular System