abdominal ganglia (ARTHRO) Ganglia of the ventral nerve cord that innervate the abdomen, each giving off a pair of principal nerves to the muscles of the segment; located between the alimentary canal and the large ventral muscles.
abdominal process (ARTHRO: Crustacea) In Branchiopoda, fingerlike projections on the dorsal surface of the abdomen.
abdominal somite (ARTHRO: Crustacea) Any single division of the body between the thorax and telson; a pleomere; a pleonite.
abduce v. [L. abducere, to lead away] To draw or conduct away.
abduct v. [L. abducere, to lead away] To draw away from position of median plane or axis.
abductin n. [L. abducere, to lead away] (MOLL: Bivalvia) Rubber-like block of protein of the inner hinge ligament of Pecten.
abductor muscle The muscle that draws an appendage or part away from an axis of the body. see adductor muscle.
aberrant a. [L. aberrans, wandering] Pertaining to a deviation from the normal type or form; abnormal; anomalous variations; different.
abient a. [L. abire, to depart] Avoiding or turning away from a source of stimulation. see adient.
abiocoen n. [Gr. a, without; bios, life; koinos, common] The non-living components of an environment.
abiogenesis n. [Gr. a, without; bios, life; genesis, beginning] The theoretical concept that life can arise from non-living matter; spontaneous generation; archebiosis; archegenesis, archigenesis. see biogenesis, neobiogenesis.
abiology n. [Gr. a, without; bios, life; logos, discourse] The study of inanimate objects; anorganology.
abiotic a. [Gr. a, without; bios, life] Pertaining to, or characterized by the absence of life.
abjugal furrow (ARTHRO: Chelicerata) In Acari, the line sepa rating the aspidosoma (prodorsum) and the podosoma of mites.
ablation n. [L. ablatus, taken away] Removal of a part as by excision or amputation.
aboral a. [L. ab, from; os, mouth] 1. Pertaining to, or situated away from the mouth; surface opposite the mouth. 2. (ECHINOD: Asteroidea) The surface opposite that bearing the mouth and ambulacral grooves; abactinal; apical; dorsal. see oral.
aboriginal a. [L. aborigineus, ancestral] 1. Of or pertaining to an aborigine, the first, original. 2. Native fauna and flora of a geographic region.
abortion n. [L. abortus, premature birth] Arrest or failure of development of any entity or normally present part or organ rendering it unfit for normal function.
abranchiate a. [Gr. a, without; branchia, gills] Pertains to being without gills.
abreptor n. [L. ab, from; reptere, to crawl] (ARTHRO: Crustacea) The postabdomen of water fleas terminating in two claws.
abscised n. [L. abscissus, cut off] Cut off squarely; with a straight margin.
abscission n. [L. abscissus, cut off] The separation of parts.
absolute a. [L. absolutus, finished, perfect, complete] Any entity existing in and of itself free from impurities or imperfections.
absorption n. [L. ab, from; sorbere, to suck] The passage of water and dissolved substances into a living cell or tissue. see adsorption.
abterminal a. [L. ab, from; terminus, limit] Passing from the end toward the center.
abullate a. [Gr. a, without; L. bulla, bubble] Lacking a bulla.
abyss n. [Gr. abyssos, the deep sea] Bottomless, sometimes used to denote very deep.
abyssal a. [Gr. abyssos, the deep sea] Pertaining to the ocean depth beyond the continental shelf; dark area of the ocean below 2,000 meters.
abyssobenthos a. [Gr. abyssos, the deep sea; benthos, depth of sea] Pertaining to all organsims that are sessile, or creep or crawl over the ocean bottom.
abyssopelagic a. [Gr. abyssos, the deep sea; pelagos, sea] Pertains to all organisms inhabiting the deep abyssal zone; they are either active swimmers, or float with the current.
acantha n. [Gr. akantha, thorn, spine] Spinous process; prickle.
acanthaceous a. [Gr. akantha, thorn, spine] Pertaining to being armed with spines or prickles.
acanthella larva (ACANTHO) Transitional larva developed from an acanthor after crossing through the gut wall into the intermediate host hemocoel; stage between an acanthor and a cystacanth in which the definitive organ systems are developed.
acantho- [Gr. akantha, thorn, spine] A prefix meaning spine.
Acanthocephala, acanthocephalans n.; n.pl. [Gr. akantha, thorn, spine; kephale, head] A phylum of parasitic pseu-docoelomate, bilateral animals distinguished by a generally eversible proboscis with recurved, sclerotized, retractable hooks; commonly called spiny-headed worms. acantho-cephalous a.
acanthocyst n. [Gr. akantha, thorn, spine; kystis, bladder] (nemer) The stylet apparatus housed in the middle (stylet bulb) portion of the proboscis, including two to several accessory stylet pouches containing replacement stylets.
acanthodion n.; pl. -dia [Gr. dim. akanthodes, thorn, spine] (ARTHRO: Chelicerata) In Acari, a tarsal seta that contains an extension of a sensory basal cell.
acanthodrilin set (ANN: Oligochaeta) With reference to male terminalia, having prostatic pores in segments xvii and xix, and male pores in segment xviii, all pores are in seminal furrows.
acanthoparia n.; pl. -iae [Gr. akantha, thorn, spine; pareion, cheek] (ARTHRO: Insecta) In Coleoptera, the lateral spiny paired region of the paria (epipharynx) in scarabaeoid larvae.
acanthophore n. [Gr. akantha, thorn, spine; phoreus, bearer] (nemer) A conical mass that forms the basis of the median stylet.
acanthophorites n. [Gr. akantha, thorn, spine; phoreus, bearer] (ARTHRO: Insecta) In Diptera, spine bearing plates at the tip of the female abdomen used to aid oviposition in soil.
acanthopod n. [Gr. akantha, thorn, spine; pous, foot] (AR-THRO: Crustacea) A barnacle appendage (cirrus) bearing a short row of strong sharp spines distally at each articulation of greater curvature, and few or no spines of lesser curvature. see centopod, basipod(ite).
acanthopore n. [Gr. akantha, thorn, spine; poros, passage] (BRYO) 1. A tubular spine in certain fossils. 2. In Stenolae-mata, sometimes referred to as style, stylet, or acan-thorod.
acanthor n. [Gr. akantha, thorn, spine] (ACANTHO) The first stage larva that emerges from the egg; the infective stage in the gut of the arthropod (intermediate host); has 6-8 blade-like hooks forming an aclid organ or rostellum.
acanthorod n. [Gr. akantha, thorn, spine; A.S. rod] (BRYO: Stenolaemata) A style or stylet. see acanthopore.
acanthosoma n. [Gr. akantha, thorn, spine; soma, body] (ARTHRO: Crustacea) In Decapoda, the last larval stage preceding the postlarva; zoea; mysis; schizopod larvae.
acanthosphenote a. [Gr. akantha, thorn, spine; sphen, wedge] (echinod: Echinoidea) Pertaining to a spine composed of solid wedges separated by porous tissue.
acanthostegous a. [Gr. akantha, thorn, spine; stegos, roof] (BRYO) Pertaining to an overlay of spines, as the ovicell.
acanthostyle n. [Gr. akantha, thorn, spine; stylos, pillar] 1. (BRYO: Stenolaemata) A type of stylet with a smooth rod core of nonlaminated calcite, with sheath laminae usually strongly deflected toward the zoarial surface as spines; usually larger than paurostyle. 2. (PORIF) A monactinal spicule covered with thorny processes.
acanthozooid n. [Gr. akantha, thorn, spine; zoon, animal; ei-dos, form] (bryo) A specialized zooid that secretes small tubules that project as spines above the colony's surface.
Acari n. [Gr. akari, mite or tick] (ARTHRO: Chelicerata) Subclass of the most diverse and species-rich group of arachnids containing the mites and ticks; formerly the order Acarina.
acariasis n. [Gr. akari, mite or tick; -iasis, diseased condition] (ARTHRO: Chelicerata) Infestation with ticks or mites, or any diseased condition resulting therefrom.
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