septula n.; pl. -ae [L. dim. septum, partition] (ARTHRO: Insecta) In Scarabaeoidea larvae, a narrow bare region of the raster: between a transverse palidium and base of the lower anal lip, or between a pair of oblique palidia diverging backward to the end of the anal slit, or between a pair of backward diverging, or parallel, or curved palidia to the inside ends of the anal slit.
septulum n.; pl. -tula [L. dim. septum, partition] 1. A small septum. 2. (BRYO) An internal membrane of a communication organ. see dietella.
septum n.; pl. -ta [L. septum, partition] 1. Any dividing wall, membrane or partition separating cavities or masses of tissue; a dissepiment. 2. (ANN) Two layers of peritoneal cells enclosing muscle fibers, and blood vessels that separate adjacent segments. 3. (ARTHRO: Crustacea) For barnacles, see transverse septum. 4. (BRACHIO) Long, narrow, elevation of the secondary (shell) layer, usually bladelike. a. In Articulata, within underlying floor of valve with high, narrow deflections of fibrous calcite starting near the primary layer. b. In Inarticulata, comparable deflections of the shell lamellae. 5. (MOLL: Cephalopoda) A calcareous tube that supports the siphuncle. 6. (MOLL: Gastropoda) A transverse plate secreted with early formed whorls of shell.
sere n. [L. serere, to join] A chain of communities that follow one another in sequence, prisere (primary sere) to a climax typical of a particular climate and geographical area. see hydrosere, xerosere, lithosere.
serial a. [L. series, a row of things] Pertaining to or consisting of or arranged in a series or row.
serial crochets (ARTHRO: Insecta) Crochets of larvae, the distribution of the bases or points of attachment. see unise-rial circle, biserial crochets, multiserial crochets.
sericate a. [L. sericus, silken] Having short, thick, silky down; sericeous.
sericin n. [L. sericus, silken] (ARTHRO: Insecta) In Lepidoptera, a protein containing a high content of the amino acid serine, that hardens in air to form the glue surrounding the threads emitted from the spinneret of the silkworm.
sericose n. [L. sericus, silken; os, mouth] (ARTHRO: Insecta) In Hymenoptera, the opening for the duct of the silk glands.
serictery, sericterium n.; pl. -teria, -teries [L. sericus, silken] (ARTHRO: Insecta) The spinning gland or glands. a. In ant larvae, used as shuttles in weaving nests. b. The silk-producing glands of a caterpillar. see silk gland.
series n. [L. series, succession] In taxonomy, the sample taken in the field by the collector, or the sample available for taxonomic study. see hypodigm.
serific glands (ARTHRO: Insecta) Glands of silk production that secrete a viscous fluid that solidifies passing through the orifice of the spinneret, emerging as two semi-crystalline threads.
serology n. [L. serum, whey; Gr. logos, discourse] The study of sera and the nature, and interactions of antigens and antibodies.
serosa n. [L. serum, whey] (ARTHRO: Insecta) The outer embryonic envelope.
serosal cuticle (ARTHRO: Insecta) An embryonic covering incorporating the vitelline membrane on the outside, and consisting of a chitinous endocuticle (white cuticle), with an epicuticle (yellow cuticle) having a second wax layer.
serotinal a. [L. serus, late] Appearing later in the season than is customary with related species.
serous a. [L. serum, whey] Secreting a watery, colorless serum.
serpentinous a. [OF. serpentine, greenish mineral] A dirty, dark green.
serrate a. [L. serra, saw] Marginal teeth or notches like a saw.
serration n. [L. serra, saw] A saw-like formation.
serratulate a. [L. serrula, small saw] Having little teeth or serrations.
serriform a. [L. serra, saw; forma, shape] Saw-toothed; having the form of a series of notches.
serrula n. [L. dim. serra, saw] (ARTHRO: Chelicerata) In spiders, a serration on the lateral margin of each maxillary lobe for cutting into prey.
serrulate a. [L. dim. serra, saw] Finely serrate; having small fine teeth or minute notches.
serum ; pl. -a n. [L. serum, whey] The liquid part of the blood; the secretion of a serous membrane.
sesquiocellus n. [L. sesqui-, one and one half; dim. oculus, eye] A large ocellate spot including a smaller one.
sessile n. [L. sedere, to sit] Incapable of movement from place to place; attached directly, without a stem or petiole; permanently attached.
sessoblast n. [L. sedere, to sit; Gr. blastos, bud] (BRYO: Phy-lactolaemata) A statobast cemented to the substrate.
seston n. [Gr. sesis, sifting] Microplankton; all organisms living or dead, swimming or floating in aquatic habitats. see nekton, neuston, plankton.
seta n.; pl. setae [L. seta, bristle] 1. A bristle, hair or filament process of the cuticle with which it articulates or through which it protrudes. see poison seta, penial seta. 2. (ANN) Chaeta. 3. (ARTHRO: Insecta) Hollow structures formed as extensions of the epidermal layer; macrotrichia or scales. 4. (ARTHRO: Crustacea) In Cirripedia, a bristle or spine on trophi and cirri. setal, setate a.
setaceous a. [L. seta, bristle] Bristlelike, slender.
setal membrane The membranous floor of a hair socket.
setal sac (ANN: Polychaeta) A pocket of the parapodial rami containing a single cell at the base, that continually produce new setae as the old are lost.
setate a. [L. seta, bristle] Provided with bristles.
setiferous a. [L. seta, bristle; ferre, to carry] Bearing setae or bristles; setigerous; chaetiferous.
setiform a. [L. seta, bristle; forma, shape] Having the shape of a bristle or seta.
setigenous a. [L. seta, bristle; Gr. genitus, to produce] Giving rise to setae.
setiger n. [L. seta, bristle; gerere, to bear] (ANN: Polychaeta) A segment carrying setae.
setigeris n. [L. seta, bristle; gerere, to bear] (ARTHRO: Insecta) A structure on the protibia similar in form and use as the strigil or scraper; the tibial comb.
setigerous a. [L. seta, bristle; gerere, to bear] Bearing setae; setiferous.
setigerous lobe (ANN: Polychaeta) The lobe of the parapodium that bears the setae.
setigerous tubercles (ARTHRO: Insecta) In Diptera, bumps occurring on the scutellum or legs, each bearing a spine or bristle at the apex.
setireme n. [L. seta, bristle; remus, oar] (ARTHRO: Insecta) In aquatic forms, the hairy, oar-like leg.
setula n.; pl. -lae; setule n.; pl. setules [L. dim. seta, bristle] (ARTHRO) Slender hair- or bristle- or thread-like, fragile setae.
setulose a. [L. dim. seta, bristle; -osus, full of] Set with short, blunt bristles.
sex n. [L. sexus, sex] The physical characteristics by which an animal is classed as male or female.
sex cell see gametes sexual congress The association of males and females for sexually reproductive purposes.
sex chromosome A special chromosome, not occurring in identical number or structure in the two sexes, usually determines sex; the X and Y chromosomes. see chromosome, autosome.
sex hormone A hormone that influences primary and secondary sexual characters and sexual behavior.
sex-limited character A character occurring in only one sex. see secondary sexual characters, sex-linked character.
sex-linked character A character controlled by a gene located in a sex chromosome. see sex chromosome.
sex-linked genes Genes in the sex chromosomes, linked in heredity to the genes determining sex.
sex mosaic Intersex; gynandromorph.
sexprostatic a. [L. sex, six; Gr. pro-, before; stare, stand] (ANN) Having 6 prostates in 3 consecutive segments.
sexradiate a. [L. sex, six; radius, ray] Having 6 radii; hexacti-nal.
sex ratio The percentage of males and females of a specified age distribution in a population.
sex reversal To change from one sex to the other, either by natural phenomena, pathology, or artificial means.
sexthecal a. [L. sex, six; Gr. theke, case] (ANN) Having 3 pairs of spermathecae.
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