Chapter 33: Invertebrates

Front 1

alimentary canal

Back 1

A digestive tract consisting of a tube running between a mouth and an anus

Front 2

ammonite

Back 2

A member of a group of shelled cephalopods that were important marine predators for hundreds of millions of years until their extinction at the end of the Cretaceous period (65.5 mya).

Front 3

amoebocyte

Back 3

An amoeba-like cell that moves by pseudopodia and is found in most animals. Depending on the species, it may digest and distribute food, dispose of wastes, form skeletal fibers, fight infections, and change into other cell types.

Front 4

arachnid

Back 4

A member of a major arthropod group, the cheliceriforms. Arachnids include spiders, scorpions, ticks, and mites.

Front 5

arthropod

Back 5

A segmented ecdysozoan with a hard exoskeleton and jointed appendages. Familiar examples include insects, spiders, millipedes, and crabs.

Front 6

book lung

Back 6

An organ of gas exchange in spiders, consisting of stacked plates contained in an internal chamber.

Front 7

brachiopod

Back 7

A marine lophophorate with a shell divided into dorsal and ventral halves. Brachiopods are also called lamp shells.

Front 8

chelicerae

Back 8

(plural, chelicerae) One of a pair of clawlike feeding appendages characteristic of cheliceriforms.

Front 9

cheliceriform

Back 9

An arthropod that has chelicerae and a body divided into a cephalothorax and an abdomen. Living cheliceriforms include sea spiders, horseshoe crabs, scorpions, ticks, and spiders.

Front 10

choanocyte

Back 10

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.

Front 11

cnidocyte

Back 11

A specialized cell unique to the phylum Cnidaria

Front 12

complete metamorphosis

Back 12

The transformation of a larva into an adult that looks very different, and often functions very differently in its environment, than the larva.

Front 13

copepod

Back 13

Any of a group of small crustaceans that are important members of marine and freshwater plankton communities.

Front 14

coral reef

Back 14

Typically a warm-water, tropical ecosystem dominated by the hard skeletal structures secreted primarily by the resident cnidarians. Some reefs also exist in cold, deep waters.

Front 15

crustacean

Back 15

A member of a subphylum of mostly aquatic arthropods that includes lobsters, crayfishes, crabs, shrimps, and barnacles.

Front 16

cuticle

Back 16

(1) A waxy covering on the surface of stems and leaves that acts as an adaptation that prevents desiccation in terrestrial plants. (2) The exoskeleton of an arthropod, consisting of layers of protein and chitin that are variously modified for different functions. (3) A tough coat that covers the body of a nematode.

Front 17

decapod

Back 17

A member of the group of crustaceans that includes lobsters, crayfishes, crabs, and shrimps.

Front 18

ecdysozoans

Back 18

Member of a group of animal phyla identified as a clade by molecular evidence. Many ecdysozoans are molting animals.

Front 19

echinoderm

Back 19

A slow-moving or sessile marine deuterostome with a water vascular system and, in larvae, bilateral symmetry. Echinoderms include sea stars, brittle stars, sea urchins, feather stars, and sea cucumbers.

Front 20

ectoproct

Back 20

A sessile, colonial lophophorate commonly called a bryozoan.

Front 21

eurypterid

Back 21

An extinct carnivorous cheliceriform also called a water scorpion.

Front 22

exoskeleton

Back 22

A hard encasement on the surface of an animal, such as the shell of a mollusc or the cuticle of an arthropod, that provides protection and points of attachment for muscles.

Front 23

foot

Back 23

(1) The portion of a bryophyte sporophyte that gathers sugars, amino acids, water, and minerals from the parent gametophyte via transfer cells. (2) One of the three main parts of a mollusc

Front 24

gastrovascular cavity

Back 24

A central cavity with a single opening in the body of certain animals that functions in both the digestion and distribution of nutrients.

Front 25

hemolymph

Back 25

In invertebrates with an open circulatory system, the body fluid that bathes tissues.

Front 26

hermaphrodite

Back 26

An individual that functions as both male and female in sexual reproduction by producing both sperm and eggs.

Front 27

hexapod

Back 27

An insect or closely related wingless, six-legged arthropod.

Front 28

incomplete metamorphosis

Back 28

A type of development in certain insects, such as grasshoppers, in which the young (called nymphs) resemble adults but are smaller and have different body proportions. The nymph goes through a series of molts, each time looking more like an adult, until it reaches full size.

Front 29

invertebrate

Back 29

An animal without a backbone. Invertebrates make up 95% of animal species.

Front 30

isopod

Back 30

A member of one of the largest groups of crustaceans, which includes terrestrial, freshwater, and marine species. Among the terrestrial isopods are the pill bugs, or wood lice.

Front 31

mandible

Back 31

One of a pair of jaw-like feeding appendages found in myriapods, hexapods, and crustaceans.

Front 32

mantle

Back 32

One of the three main parts of a mollusc

Front 33

mantle cavity

Back 33

A water-filled chamber that houses the gills, anus, and excretory pores of a mollusc.

Front 34

medusa

Back 34

The floating, flattened, mouth-down version of the cnidarian body plan. The alternate form is the polyp.

Front 35

mesohyl

Back 35

A gelatinous region between the two layers of cells of a sponge.

Front 36

molting

Back 36

A process in ecdysozoans in which the exoskeleton is shed at intervals, allowing growth by the production of a larger exoskeleton.

Front 37

myriapod

Back 37

A terrestrial arthropod with many body segments and one or two pairs of legs per segment. Millipedes and centipedes comprise the two classes of living myriapods.

Front 38

nematocyst

Back 38

In a cnidocyte of a cnidarian, a specialized capsule-like organelle containing a coiled thread that when discharged can penetrate the body wall of the prey.

Front 39

osculum

Back 39

A large opening in a sponge that connects the spongocoel to the environment.

Front 40

parthenogenesis

Back 40

Asexual reproduction in which females produce offspring from unfertilized eggs.

Front 41

planarian

Back 41

A free-living flatworm found in unpolluted ponds and streams.

Front 42

protonephridium

Back 42

(singular, ) An excretory system, such as the flame bulb system of flatworms, consisting of a network of tubules lacking internal openings.

Front 43

radula

Back 43

A straplike rasping organ used by many molluscs during feeding.

Front 44

spongocoel

Back 44

The central cavity of a sponge.

Front 45

suspension feeder

Back 45

An aquatic animal, such as a sponge, clam, or baleen whale, that feeds by sifting small food particles from the water.

Front 46

torsion

Back 46

In gastropods, a developmental process in which the visceral mass rotates up to 180°, causing the animal’s anus and mantle cavity to be positioned above its head.

Front 47

trochophore larva

Back 47

Distinctive larval stage observed in some lophotrochozoan animals, including some annelids and molluscs.

Front 48

tube foot

Back 48

One of numerous extensions of an echinoderm’s water vascular system. Tube feet function in locomotion, feeding, and gas exchange.

Front 49

visceral mass

Back 49

One of the three main parts of a mollusc

Front 50

water vascular system

Back 50

A network of hydraulic canals unique to echinoderms that branches into extensions called tube feet, which function in locomotion, feeding, and gas exchange.

Front 51

arthro

Back 51

jointed

Front 52

pod

Back 52

foot (Arthropoda: segmented coelomates with exoskeletons and jointed appendages)

Front 53

arachn

Back 53

spider (Arachnida: the arthropod group that includes scorpions, spiders, ticks, and mites)

Front 54

brachio

Back 54

the arm (brachiopod: also called lamp shells, these animals superficially resemble clams and other bivalve molluscs, but the two halves of the brachiopod shell are dorsal and ventral to the animal rather than lateral, as in clams)

Front 55

zoa

Back 55

animal (bryozoan: colonial animals (phylum Ectoprocta) that superficially resemble mosses)

Front 56

bryo

Back 56

moss

Front 57

choano

Back 57

a funnel

Front 58

cheli

Back 58

a claw (chelicerae: clawlike feeding appendages characteristic of the cheliceriform group)

Front 59

cyte

Back 59

cell (choanocyte: flagellated collar cells of a sponge)

Front 60

cnido

Back 60

a nettle (cnidocytes: unique cells that function in defense and prey capture in cnidarians)

Front 61

coel

Back 61

hollow (spongocoel: the central cavity of a sponge)

Front 62

cope

Back 62

an oar (copepods: a group of small crustaceans that are important members of marine and freshwater plankton communities)

Front 63

cuti

Back 63

the skin (cuticle: the exoskeleton of an arthropod)

Front 64

deca

Back 64

ten (decapod: a large group of crustaceans that includes lobsters, crayfish, crabs, and shrimp)

Front 65

diplo

Back 65

double (Diplopoda: the millipede class)

Front 66

echino

Back 66

spiny

Front 67

derm

Back 67

skin (echinoderm: sessile or slow-moving animals with a thin skin that covers an exoskeleton

Front 68

eury

Back 68

broad, wide

Front 69

pter

Back 69

a wing, a feather, a fin (eurypterid: mainly marine and freshwater, extinct cheliceriforms

Front 70

exo

Back 70

outside (exoskeleton: a hard encasement on the surface of an animal)

Front 71

gastro

Back 71

stomach

Front 72

vascula

Back 72

a little vessel (gastrovascular cavity: the central digestive compartment, usually with a single opening that functions as both mouth and anus)

Front 73

hermaphrod

Back 73

with both male and female organs (hermaphrodite: an individual that functions as both male and female in sexual reproduction by producing both sperm and eggs)

Front 74

in

Back 74

without (invertebrates: animals without a backbone)

Front 75

iso

Back 75

equal (isopods: one of the largest groups of crustaceans, primarily marine, but including pill bugs common under logs and moist vegetation next to the ground)

Front 76

lopho

Back 76

a crest, tuft

Front 77

phora

Back 77

to carry (lophophore: a crown of ciliated tentacles that function in feeding and surround the mouth)

Front 78

meso

Back 78

the middle

Front 79

meta

Back 79

change

Front 80

cyst

Back 80

a bag (nematocysts: the stinging capsules in cnidocytes, unique cells that function in defense and capture of prey)

Front 81

nephri

Back 81

the kidney (metanephridium: in annelids, a type of excretory tubule with internal openings called nephrostomes that collect body fluids)

Front 82

oscul

Back 82

a little mouth (osculum: a large opening in a sponge that connects the spongocoel to the environment)

Front 83

partheno

Back 83

without fertilization

Front 84

genesis

Back 84

producing (parthenogenesis: a type of reproduction in which females produce offspring from unfertilized eggs)

Front 85

plan

Back 85

flat or wandering (planarians: flatworms that prey on smaller animals or feed on dead animals)

Front 86

tri

Back 86

three

Front 87

lobi

Back 87

a lobe (trilobite: an extinct group of arthropods with pronounced segmentation)

Front 88

trocho

Back 88

a wheel (trochophore: distinctive larval stage observed in certain invertebrates, including some annelids and molluscs)