University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Armand R. Maggenti Online Dictionary of Invertebrate Zoology Parasitology, Harold W. Manter Laboratory of September 2005 Online Dictionary of Invertebrate Zoology: B Mary Ann Basinger Maggenti University of California-Davis Armand R. Maggenti University of California, Davis Scott Lyell Gardner University of Nebraska - Lincoln, [email protected] Follow this and additional works at: https://digitalcommons.unl.edu/onlinedictinvertzoology Part of the Zoology Commons Maggenti, Mary Ann Basinger; Maggenti, Armand R.; and Gardner, Scott Lyell, "Online Dictionary of Invertebrate Zoology: B" (2005). Armand R. Maggenti Online Dictionary of Invertebrate Zoology. 17. https://digitalcommons.unl.edu/onlinedictinvertzoology/17 This Article is brought to you for free and open access by the Parasitology, Harold W. Manter Laboratory of at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Armand R. Maggenti Online Dictionary of Invertebrate Zoology by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Online Dictionary of Invertebrate Zoology 110 secta) The thoracic legs. B baenosome n. [Gr. bainein, to walk; soma, body] (ARTHRO: Insecta) The thorax. Baer's disc (PLATY: Trematoda) In Aspidogastrea, the large, ventral sucker. see opisthaptor. baccate a. [L. bacca, berry] Berry-like in appearance; bacci- bailer n. [F. baille, a bucket] (ARTHRO: Crustacea) An exopod form. of the maxilla of crayfish and lobsters that functions in bacillary a. [L. bacillum, little stick] Rod-shaped, or consisting regulating the flow of water in the gill chamber; scaphog- of rod-shaped structures. nathite. bacillary band (NEMATA) A modification of the hypodermis, balanced lethals Heterozygotes in which a gene mutation or consisting of glandular and nonglandular cells. chromosome structural change occurs that blocks normal bacillary layer see brush border development and is fatal before sexual maturity. see lethal factor. bacilliform a. [L. bacillum, little stick; forma, shape] 1. Rod- shaped. 2. (ARTHRO: Insecta) In certain male Diptera, re- balanced load A term describing a decrease in the overall fit- fers to a pair of sclerites in the postabdomen joining the ness of a population due to the component genes that are hypandrium and epandrium. maintained in the population because they add to fitness in different combinations, i.e., heterozygotes. back n. [A.S. baec, the rear or dorsal part] The dorsal or upper surface. balanced polymorphism A polymorphism maintained in the same breeding population by a selective superiority of the back-cross A cross between a heterozygote and one of its par- heterozygotes over either type of homozygotes. see tran- ents. sient polymorphism. back-mutation The reversion by mutation of a mutant gene to balancers n.pl. [L. bis, two; lanx, plate, pan of a balance] (AR- the form from which it was derived. THRO: Insecta) The halteres of Diptera. bacteremia n. [Gr. bakterion, small rod; haima, blood] The balanoid a. [Gr. balanos, acorn; eidos, like] Acorn shaped. presence of bacteria in the hemolymph or blood of inverte- brates, without production of harmful toxins or other dele- balantin, balantine n. [Gr. balantidion, little bag] (ANN: Oli- terious effects. gochaeta) Male and prostatic pores in segment xix. bacteriophagous a. [Gr. bakterion, small rod; phagein, to Balbiani's body/nucleus The yolk nucleus. eat] Feeding on bacteria. Balbiani ring (ARTHRO: Insecta) In chironomid Diptera, a large baculiform a. [L. baculum, stick or rod; forma, shape] Ap- RNA puff on chromosome IV of the salivary glands during pearing rod- or staff-like. larval development. baculite n. [L. baculum, stick or rod] (MOLL: Cephalopoda) A bald a. [ME. balled, equivalent to ball, white spot] Lacking spe- straight shelled ammonite, extinct at the end of the Creta- cific hair or other surface covering. ceous Period. Baldwin effect The condition in which an organism can stay in baenomere n. [Gr. bainein, to walk; meros, part] (ARTHRO: a favorable environment, with modification of the pheno- Insecta) The leg-bearing thoracic segment. type by mutation and selection, until genetic assimilation has been achieved. baenopoda n. [Gr. bainein, to walk; pous, foot] (ARTHRO: In- 111 Maggenti and Gardner Online Dictionary of Invertebrate Zoology 112 ballonets n.pl. [OHG. balla, a spherical body] (NEMATA: Se- basal canal (BRYO) The circumoral lacuna of the lophophore cernentea) Four inflated areas in the cephalic region, im- into which the internal lacunae of all the tentacles open. mediately posterior to the lips, that form a collarette in basal diaphragm (BRYO: Stenolaemata) The diaphragm acting Gnathostomatidae; head bulb of some authors. as the floor of the living chamber. ballooning n. [OHG. balla, a spherical body] (ARTHRO: Cheli- basal disc (BRYO: Stenolaemata) The encrusting proximal- cerata) Flying through the air on silken lines spun by spi- most part of an ancestrula. ders. basalia a. [L. basis, base] (PORIF) Pertaining to spicules pro- band n. [A.S. bindan, band] 1. A transverse marking broader truding from the lower surface of a sponge. than a line. 2. (ARTHRO: Insecta) a. In Diptera, the chro- mosome pairing of like chromomeres that produce the gi- basalis n. [L. basis, base] (ARTHRO: Insecta) The main man- ant chromosomes. b. In male Lepidoptera, a descriptive dibular sclerite to which all other parts are joined. term of a linear series of cornuti. basal knobs (NEMATA) The posterior knobs of the oral stylet. barb n. [L. barba, beard] 1. Any spine or hair-like bristle with a see stylet knobs. process projecting obliquely or crosswise from the surface. basal lamina (PORIF) The attachment surface. 2. A spine with teeth pointing backward. basal margin (ARTHRO: Crustacea) In Cirripedia, the lower barbate, barbatus a. [L. barba, beard] Tufts or fascicles of edge of the scutum, tergum or other plates. hair or short bristles; bearded; having tufts of hair. basal plates 1. (ECHINOD: Crinoidea) A cycle of 5 aboral calyx barbula n.; pl. -lae [L. dim. barba, beard] (ARTHRO: Insecta) plates in primitive stalked crinoids. see radial plates. 2. In Coleoptera, a tuft of hairs or short bristles at the sides of (NEMATA) The circular base of the cephalic framework, the abdomen near the anal region of scarabaeoid larvae. composed of an annular structure with posteriorly directed bark n. [Sw. bark, rind] (PORIF) The outer casing of spongin of rim, the basal ring, and six radial elements. those having discontinuous fiber structure. basal platform (BRYO: Gymnolaemata) In Cheilostomata, the baroceptor, baroreceptor n. [Gr. baros, weight; L. capere, to multizooidal skeletal layers of the basal zooidal walls; basal take] An organ perceiving changes in pressure. plate. barotropism n. [Gr. baros, weight; tropein, to turn] A re- basal ring (NEMATA) The annular structure that extends poste- sponse to pressure stimuli. riorly from the outer margin of the basal plate of the ce- phalic framework. barrier n. [OF. barre, bar] An obstacle or obstruction that lim- its the spread or distribution of animals. basal sclerites (ARTHRO: Insecta) In Diptera, two lateral, ver- tical lamellae uniting ventrally to form a trough that lodges barrier reef see coral reef the pharynx. basad adv. [L. basis, base; ad, to] Toward the base. basal suture (ARTHRO: Insecta) In Isoptera, the line along basal a. [L. basis, base] Pertaining to the base; near the point which the wing separates from the body and shedding of attachment of a structure or appendage. takes place. basalar a. [L. basis, base; ala, wing] (ARTHRO: Insecta) Per- basal window (BRYO: Gymnolaemata) In Cheilostomata, the taining to the sclerites below the wing base. subcentral, uncalcified section of an encrusting colony's basal bud (BRYO: Gymnolaemata) The bud arising from the exterior basal zooidal wall. basal wall of the parent zooid. see distal bud. basal zooidal wall (BRYO) In Stenolaemata and Gymnolae- 113 Maggenti and Gardner Online Dictionary of Invertebrate Zoology 114 mata, the interior or exterior zooidal supporting wall, nor- basilemma see basement membrane mally parallel to the orificial wall. basimandibula n. [L. basis, base; mandibulum, lower jaw] base n.; pl. bases [L. basis, base] 1. The bottom of anything. (ARTHRO: Insecta) In Orthoptera, a narrow sclerite between 2. The main ingredient in anything that is a fundamental the mandible and gena; a trochantin. element or constituent. 3. The portion of a body to which basimaxilla n. [L. basis, base; maxilla, upper jaw] (ARTHRO: an appendage or structure is attached. 4. (MOLL) The ex- Insecta) The basal maxillary sclerite. tremity opposite the apex of a shell spire. basimetrical n. [Gr. basis, base; metrikos, of measuring] The basement membrane 1. The noncellular membrane underly- vertical or horizontal distribution of organisms at the sea- ing the epidermal cells of the body wall that separates it bottom. from the body cavity. 2. (ARTHRO: Insecta) Applied also to the inner surface of the eye; the basilemma. basinym n. [Gr. basis, base; onyma, name] The name upon which new names of species or higher classifications has basicarnal angle (ARTHRO: Crustacea) In Cirripedia, the inter- been based. see isonym. section of the basal and median dorsal margins of the dor- sal plate (tergum). basioccludent angle (ARTHRO: Crustacea) In Cirripedia, the intersection of basal and occludent margins of the scutum. basicerite n. [Gr. basis, base; keras, horn] (ARTHRO: Crusta-