calciferous glands
Glands in an earthworm that secrete calcium ions into the gut.
calorie
(L. calere, to be warm). unit of heat defined as the amount of heat required to heat 1 g of water from 14.5 to 15.5°C; 1 cal= 4.184 joules in the International System of units.
calyx
(L. bud cup of a flower). Any of various cup-shaped zoological structures.
cancellous
(L. cancelli, latticework,+ os full of). Having a spongy or porous structure.
capitulum
(L. small head). Term applied to small, headlike structures of various organisms, including projection from body of ticks and mites carrying mouthparts.
captacula
(L. captare, to lie in wait for). Tentacles extending from head of scaphopod mollused in feeding.
carapace
(F. from Sp. carapacho, shell). Shieldlike plate covering the cephalothorax of certain crurtle.
carbohydrate
(L. carbo, charcoal, + Gr. hydor, water). Compounds of carbon, hydrogen, and oxygen having the generalized formula (CH2O)n; aldehyde or ketone derivatives of polyhydric alcohols, with hydrogen and oxygen atoms attached in a 2:1 ratio.
carboxyl
(carbon + oxygen + yl, chemical radical suffix). The acid
group of organic molecules (-COOH.)
cardiac
(Gr. kardia, heart). Belonging or relating to the heart.
carinate
(L. carina, keel). Having a keel, in particular the flying birds with a keeled sternum for the insertion of flight muscles.
carnivore
(L. carnivorous, flesh eating). One of the flesh-eating mammals of the order Carnivora. Also, any organism that eats animals. Adj., carnivorous
carotene
(L. carota, carrot, + ene, unsaturated straight-chain hydrocarbons). A red, orange, or yellow pigment belonging to the group of carotenoids; precursor of vitamin A.
carrying capacity
The maximum number of individuals that can persist under specified environmental conditions.
cartilage
(L. cartilago; akin to L. cratis, wickerwork). A translucent elastic tissue that makes up most of the skeleton of embryos, very young vertebrates, and adult cartilaginous fishes, such as sharks and rays; in higher forms much of it is converted into bone.
caste
(kast) (L. castus,pure, separated). One
of the polymorphic forms within an insect
society, each caste having its specific duties,
as queen, worker, soldier, and so on.
catabolism
(Gr. kata, downward, + bol, to throw,+ ism, suffix meaning state of condition). Destructive metabolism; process in which complex molecules are reduced to simpler ones.
catadromous
(Gr. kata, down, + dromos, a running). Refers to fishes that
migrate from fresh water to the ocean to
spawn.
catalyst
(Gr. kata, down,+ lysis, a loosening). A substance that accelerates a chemical reaction but does not become a part of the end product.
caudal
(L: cauda, tail).Constituting,
belonging to, or relating to a tail.
caveolae
(L. cavea, a cave, + dim. suffix). The invaginated vesicles
and pits in potocytosis.
cDNA
See complementary DNA.
cecum
(L. caecus, blind). A blind pouch at the beginning of the large intestine; any similar pouch.
cell-mediated immune response
Immune response involving cell surfaces only, not antibody production, specifically the TH1 arm of the immune response. Contrast humoral immune response
cellulose
(L. cella, small room). Chief polysaccharide constituent of the cell wall of green plants and some fungi; an insoluble carbohydrate (C6H10O5)n that is converted into glucose by hydrolysis.
centriole
(Gr. kentron, center of a circle, + L. ola, small). A minute cytoplasmic organelle usually found in the centrosome and considered to be the active division center of the animal cell; organizes spindle fibers during mitosis and meiosis. Same structure as basal body or kinetosome.
centrolecithal
(Gr. kentron, center, + lekithos, yolk, + Eng. al, adjective). Pertaining to an insect egg with the yolk concentrated in the center.
centromere
(Gr. kentron, center, + meros, part). A localized constriction in a characteristic position on a given chromosome, bearing the kinetochore.
centrosome
(Gr. kentron, center, + soma, body). Microtubule organizing center in nuclear division in most eukaryotic cells; in animals and many unicellular organisms it surrounds the centrioles.
cephalization
(Gr. kephale, head). The process by which specialization, particularly of the sensory organs and appendages, become localized in the head end of animals.
cephalothorax
(Gr. kephale, head, + thorax). A body division found in many Arachnida and higher Crustacea in which the head is fused with some or all of the thoracic segments.
cercaria
(Gr. kerkos, tail,+ L. aria, like or connected with). Tadpolelike larva of trematodes (flukes).
cervical
(L. cervix, neck). Relating to a neck.
character
A component of phenotype (including specific molecular, morphological, behavioral or other features) used by systematists to diagnose species or higher taxa, or to evaluate phylogenetic relationships among different species or higher taxa, or relationships among populations within a species.
charging
In protein synthesis, a reaction catalyzed by tRNA synthetase, in which an amino acid is attached to its particular tRNA molecule.
chelicera
pl. chelicerae (Gr. chele, claw, + keras, horn). One of a pair of the most anterior head appendages on the members of the subphylum Chelicerata.
chelipeds
(Gr. chele, claw, + L. pes, foot). Pincerlike first pair of legs in most decapod crushing.
chemoautotroph
(Gr. chemeia, transm autos, self, + trophos, feeder). An organism utilizing inorganic compounds as a source of energy.
chemotaxis
(Gr. chemeia, an inf taxo> tasso, to put in order). Orientation movement of cells or organisms in response to a chemical stimulus.
chemotroph
(Gr. chemeia, an infusion, + trope, to turn). An organism that
derives nourishment from inorganic substances without using chlorophyll.
chiasma
, pl. chiasmata (Gr. cross). An intersection or crossing, as of nerves; a connection point between homologous chromatids where crossing over has occurred at synapsis.
chitin
(Fr. chitine, from Gr. chiton,
tunic). A horny substance that forms part of the cuticle of arthropods and is found sparingly in certain other invertebrates; a nitrogenous polysaccharide insoluble in water, alcohol, dilute acids, and digestive juices of most animals.
chlorocruorin
(Gr. chloros, light green, + L. cruor, blood). A greenish iron-containing respiratory pigment dissolved in the blood plasma of certain marine polychaetes.
chlorogogen cells
(Gr. chloros, light green, + agogos, a leading, a gustered around the digestive tract of certain annelids; apparently they aid in elimination of nitrogenous wastes and in food transport.
chlorophyll
(Gr. chloros, light green, + phyllon, leaf). Green pigment found in plants and in some animals; necessary for photosynthesis.
chloroplast
(Gr. chloros, light green, + plastos, molded). A plastid containing chlorophyll and usually other pigments, found in cytoplasm of plant cells.
choanocyte
(Gr. choane, fkytos, hollow vessel). One of the flagellate collar cells that line cavities and canals of sponges.
cholinergic
(Gr. chole, bile, + ergon, work). Type of nerve fiber that releases acetylcholine from axon terminal.
chorion
(Gr. chorion, skin). The outer of the double membrane that surrounds the embryo of reptiles, birds, and mammals; in mammals it contributes to the placenta.
choroid
(Gr. chorion, skin, + eidos, form). Delicate, highly vascular membrane; in vertebrate eye; the layer between the retina and sclera.
chromatid
(Gr. chromato, from chroma, color, + L. id, feminine stem for particle of specified kind). A replicated chromosome joined to its sister chromatid by the centromere; separates and becomes daughter chromosome at anaphase of mitosis or anaphase of the second meiotic division.
chromatin
(Gr. chroma, color). The nucleoprotein material of a chromosome; the hereditary material containing DNA.
chromatophore
(Gr. chroma, color, + pherein, to bear). Pigment cell, usually in the dermis, in which usually the pigment can be dispersed or concentrated.
chromomere
(Gr. chroma, color, + meros, part). One of the chromatin granules of characteristic size on the chromosome; may be identical with a gene or a cluster of genes.
chromonema
(Gr. chroma, color, + nema, thread). A convoluted thread in prophase of mitosis or the central thread in a chromosome.
chromoplast
(Gr. chroma, color, + plastos, molded). A plastidcontaining pigment.
chromosome
(Gr. chroma, color, + soma, body). A complex body, spherical or rod shaped, that arises from the nuclear network during mitosis, splits longitudinally, and carries a part of the organism's genetic information as genes composed of DNA.
chrysalis
(L. from Gr. chrysos, gold). The pupal stage of a butterfly.
chyme
(Gr. chymos,juice). Semifluid mass of partly digested food in stomach and small intestine as digestion proceeds.
cilium
, pl. cilia (L. eyelid). A hairlike, vibratile organelle process found on many animal cells. Cilia may be used in moving particles along the cell surface or, in ciliate protozoans, for locomotion.
cinclides
, sing. cinclis (Gr. kinklis, latticed gate or partition). Small pores in the external body wall of sea anemones for extrusion of acontia.
circadian
(L. circa, arodies, day). Occurring at a period of approximately 24 hours.
cirrus
(L.curl). A hairlike tuft on an insect appendage; locomotor organelle of fused cilia; male copulatory organ of some invertebrates.
cisternae
(L. cista, box). Space between membranes of the endoplasmic reticulum within cells.
cistron
(L. cista, box). A series of codons in DNA that code for an entire polypeptide chain.
clade
(Gr. klados, branch). A taxon or other group consisting of an ancestral species and all of its descendants, forming a distinct branch on a phylogenetic tree.
cladistics
(Gr. klados, branch, sproutionarily derived characteristics so that the arrangement will reflect phylogenetic relationships.
cladogram
(Gr. klados, branch, + gramma, letter). A branching diagram showing the pattern of sharing of evolutionarily derived characters among species or higher taxa.
clathrin
(L. chathri, latticework). A protein forming a lattice structure lining the invaginated pits during receptor-mediated endocytosis.
cleavage
(O.E. cleofan, to cut). Process of nuclear and cell division in animal zygote.
climax
(Gr. klimax, ladder). Stage of relative stability attained by a community of organisms, often the culminating development of a natural succession. Also, orgasm.
climax community
(Gr. klimax, ladder, staircase, climax). A self-perpetunity of organisms that continues as long as environmental conditions under which it developed prevail.
clitellum
(L. clitellae, packsaddle). Thickened saddlelike portion of certain midbody segments of many oligochaetes and leeches.
cloaca
(L. sewer). Posterior chamber of digestive tract in many vertebrates, receiving feces and urogenital products. In certain invertebrates, a terminal portion of digestive tract that serves also as respiratory, excretory, or reproductive tract.
clone
(Gr. klon, twig). All descendants derived by asexual reproduction from a single individual.
cnidoblast
(Gr. knide, nettle, + blastos, germ). See cnidocyte.
cnidocil
(Gr. knide, nettle, + L. cilium, hair). Modified cilium on nematocyst-bearing cnidocytes in cnidarians; triggers nematocyst.
cnidocyte
(Gr. knide, nettle, + kytos, hollow vessel). Modified interstitial cell that holds the nematocyst; during development of the nematocyst, the cnidocyte is a cnidoblast.
coacervate
(L. coacervatus, to heap up). An aggregate of colloidal droplets
held together by electrostatic forces.
coagulation
Process in which a series of enzymes are activated, resulting in clotting of blood.
cochlea
(L. snail, from Gr. kochlos, a shellfish). A tubular cavity of the inner ear containing the essential organs of hearing; occurs in crocodiles, birds, and mammals; spirally coiled in mammals.
cocoon
(Shell). Protective covering of a resting or developmental stage, sometimes used to refer to both the covering and its contents; for example, the cocoon of a moth or the protective covering for the developing embryos in some annelids.
codominance
See intermediate inheritance
codon
(L. code, + on). In messenger RNA a sequence of three adjacent nucleotides that codes for one amino acid.
coelenteron
(Gr. koilos, hollow,+ enteron, intestine). Internal cavity of a cnidarian; gastrovascular cavity; archenteron.
coelom
(Gr. koiloma, cavity). The body cavity in triploblastic animals, lined with mesodermal peritoneum.
coelomocyte
(Gr. koiloma, cavity,+ kytos, hollow vessel). Another name for amebocyte; primitive or undifferentiated cell of the coelom and the water-vascular system.
coelomoduct
(Gr.koilos, hollow, + L. ductus, a leading). A duct that carries gametes or excretory products (or both) from the coelom to the exterior.
coenecium,coenoecium
(Gr. koinos, common,+ oikion, house).The
common secreted investment of an
ectoproct colony; may be chitinous,
gelatinous, or calcareous.
coenenchyme
(Gr. koinos, shared in common,+ enchyma, something poured in). Extensive mesogleal tissue between the polyps of an alcyonarian (phylum Cnidaria) colony.
coenocytic
(Gr. koinos, common, + kytos, hollow vessel). A tissue in which the nuclei are not separated by cell membranes; syncytial.
coenosarc
(Gr. koinos, shared in common,+ sarkos, flesh). The inner, living part of hydrocauli in hydroids.
coenzyme
(L. prefix, co, with, + Gr. enzymos, leavened, from en, in, + zyme, leaven). A required substance in the activation of an enzyme; a prosthetic or nonprotein constituent of an enzyme.
collagen
(Gr. kolla, glue, + genos, descent). A structural protein, the most abundant protein in the animal kingdom, characterized by high content of the amino acids glycine, alanine, proline, and hydroxyproline.
collenchyme
(Gr. kolla, glue, + enchyma, infusion).A gelatinous mesenchyme containing undifferentiated cells; found in cnidarians and ctenophores.
collencyte
(Gr. kolla, glen, in, + kytos, hollow vessel). A type of cell in sponges that is star shaped and apparently contractile.
colloblas
t (Gr. kolla, glue+ blastos, germ). A glue-secreting cell on the tentacles of ctenophores.
colloid
(Gr. kolla, glue + eidos, form). A two-phase system in which particles of one phase are suspended in the second phase.
columella
(L. small column).
Central pillar in gastropod shells.
comb plate
One of the plates of fused cilia that are arranged in rows for ctenophore locomotion.
commensalism
(L. cum, together with, + mensa, table). A relationship in which one individual lives close to or on another and benefits, and the host is unaffected; often symbiotic.
community
(L. communitas community,
fellowship). An assemblage of organisms
that are associated in a common
environment and interact with each other in
a self-sustaining and self-regulating relation.
competition
Some degree of overlap in ecological niches of two populations in the same community, such that both depend on the same food source, shelter, or other resources, and negatively affect each other's survival.
complement
Collective name for a series of enzymes and activators in the blood, some of which may bind to antibody and may lead to rupture of a foreign cell.
complementary DNA (cDNA)
DNA prepared by transcribing the base sequence from mRNA into DNA by reverse transcriptase; also called copy DNA.
compound
A substance whose molecules are composed of atoms of two or more elements.
condensation reaction
A chemical reaction in which reactant molecules are combined by the removal of a water molecule (a hydrogen from one and a hydroxyl from the other reactant).
condyle
(Gr. kondylos, bump). A
process on a bone used for articulation.
conjugation
(L. conjugare, to yoke together). Temporary union of two ciliate protozoa while they are exchanging chromatin material and undergoing nuclear phenomena resulting in binary fission. Also, formation of cytoplasmic bridges between bacteria for transfer of plasmids.
conspecific
(L. com, together,+ species). A member of the same species.
contractile vacuole
A clear fluid-filled cell vacuole in protozoa and a few lower metazoa; takes up water and releases it to the outside in a cyclical manner, for osmoregulation and some excretion.
control
That part of a scientific experiment to which the experimental variable is not applied but which is similar to the experimental group in all other respects.
coprophagy
(Gr. kopros, dung, + phagein, to eat). Feeding on dung or excrement as a normal behavior among animals; reinjestion of feces.
copulation
(Fr. from L. copulare, to coual union to facilitate the reception of sperm by the female.
copy DNA
See complementary DNA.
coralline algae
Algae that precipitate calcium carbonate in their tissues; important contributors to coral reef mass.
corium
(Leather). The deep layer of the skin; dermis.
cornea
(L. corneus, horny). The outer transparent coat of the eye.
corneum
(L. corneus, horny). Epithelial layer of dead, keratinized cells. Stratum corneum.
cornified
(L. corneus, horny). Adjective for conversion of epithelial cells into nonliving, keratinized cells.
corona
(L. crown). Head or upper portion of a structure; ciliated disc on anterior end of rotifers.
corpora allata
(L. corpus, body, + allatum, aided). Endocrine glands in insects that produce juvenile hormone.
corpora cardiaca
(L. corpus, body, + Gr. kardiakos, belonging to the heart). Paired organs behind the brain of insects, serve as storage and release organs for brain hormone.
cortex
(L. bark). The outer layer of a structure.
covalent bond
A chemical bond in which electrons are shared between atoms.
coxa, coxopodite
(L. coxa, hip, + Gr. pous, podos, foot). The proximal joint of an insect or arachnid leg; in cr
creatine phosphate
High-energy phosphate compound found in the muscle of vertebrates and some invertebrates, used to regenerate stores of ATP.
cretin
[dialect], fr. L. christianus, Christian, to indicate idiots so afflicted were also human with severe mental, somatic, and sexual retardation resulting from hypothyroidism during early stages of development.
crista
, pl. cristae (L. crista, crest). A crest or ridge on a body organ or organelle; a platelike projection formed by the inner membrane of mitochondrion.
crossing over
Exchange of parts of nonsister chromatids at synapsis in the first meiotic division.
cryptobiotic
(Gr. kryptos, hidden, + bioticus, pertaining to life). Living in concealment; refers to insects and other animals that live in secluded situations, such as underground or in wood; also tardigrades and some nematodes, rotifers, and others that survive harsh environmental conditions by assuming for a time a state of very low metabolism.
ctenidia
(Gr. kteis, comb). Comblike structures, especially gills of molluscs; also applied to comb plates of Ctenophora.
ctenoid scales
(Gr. kteis, ktenos, comb). Thin, overlapping dermal scales of the more advanced fishes; exposed posterior margins have fine, toothlike spines.
cupula
(L. little tub).Small inverted cup-like structure housing another structure; gelatinous matrix covering hair cells in lateral line and equilibrium organs.
cuticle
(L. cutis, skin). A protective, noncellum organic layer secreted by the external epithelium (hypodermis) of many invertebrates. In higher animals the term refers to the epidermis or outer skin.
cyanobacteria
(Gr. kyanos, a dark-blue substance, + bakterion, dim. of baktron, a staff). Photosynthetic prokaryotes, also called blue-green algae, cyanophytes.
cyanophyte
(Gr. kyanos, a dark-blue substance, + phyton, plant). A cyanobacteriue-green alga.
cyclin
A protein important in the control of the cell division cycle and mitosis.
cycloid scales
(Gr. kyklos, circle). Thin, overlapping dermal scales of the more primitive fishes; posterior margins are smooth.
cydippid larva
(Gr. kydippe, mythological Athenian maiden). Freeswimming larva of most ctenophores; superficially similar to the adult.
cynodonts
(Gr. kynodon, canine tooth). A group of mammal-like carnivorous synapsids of the upper Permian and Triassic.
cyrtocyte
(Gr. kyrte, a fish basket, cage, + kytos, hollow vessel). A protonephridial cell with a single flagellum enclosed in a cylinder of cytoplasmic rods.
cystacanth
(Gr. kystis, bladder,pouch + akantha, thorn). Juvenile stage of an acanthocephalan that is infective to the definitive host.
cysticercoid
(Gr. kystis, bladder, + kerkos, tail, + eidos, form). A type of juvenile tapeworm composed of a solid-bodied cyst containing an invaginated scolex; contrast with
cysticercus
cysticercus
(Gr. kystis, bladder, + kerkos, tail). A type of juvenile tapeworm in which an invaginated and introverted scolex is contained in a fluid-filled bladder; contrast with cysticercoid
cystid
(Gr. kystis, bladder). In an ectoproct, the dead secreted outer parts plus the adherent underlying living layers.
cytochrome
(Gr. kytos, hollow vessel, + chroma, color). Several ironcontaining pigments that serve as electron carriers in aerobic respiration.
cytokine
(Gr. kytos, hollow vessel, + kinein, to move). A molecule secreted by an activated or stimulated cell, for example, macrophages, that causes physiological changes in certain other cells.
cytokinesis
(Gr. kytos, hollow vessel, + kinesis, movement). Division of the cytoplasm of a cell.
cytopharynx
(Gr. kytos, hollow vessel, + pharynx, throat). Short tubular gullet in ciliate protozoa.
cytoplasm
(Gr. kytos, hollow vessel,+ plasma, mold). The living matter of the cell, excluding the nucleus.
cytoproct
(Gr. kytos, hollow vessel, + proktos, anus). Site on a protozoan
where undigestible matter is expelled.
cytopyge
(Gr. kytos, hollow vessel, + pyge, rump or buttocks). In some protozoa, localized site for expulsion of wastes.
cytosol
(Gr. kytos, hollow vessel,+ L. sol, from solutus, to loosen). unstructured portion of the cytoplasm in which the organelles are bathed.
cytosome
(Gr. kytos, hollow vessel, + soma, body). The cell body inside the plasma membrane.
cytostome
(Gr. kytos, hollow vessel,+ stoma,mouth). The cell mouth in many protozoa.
cytotoxic T cells
(Gr. kytos, hollow vessel,+ toxin). A special T cell activated during cellmediated immune responses that recognizes and destroys virus-infected cells.
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