Oolemma see vitelline membrane

oophagy n. [Gr. oion, egg; phagein, to eat] 1. The eating of eggs; egg cannibalism. 2. (ARTHRO: Insecta) In social insects, eating its own or nestmate's eggs.

oophore n. [Gr. oion, egg; phoreus, carrier] (ANN: Oli-gochaeta) The egg case or capsule.

ooplasm n. [Gr. oion, egg; plasma, formed or molded] The cytoplasm of an egg.

oopod n. [Gr. oion, egg; pous, foot] (ARTHRO: Insecta) A component part of a sting or ovipositor.

oosperm n. [Gr. oion, egg; sperma, seed] A fertilized ovum; a zygote; an ooblastema.

oosphere n. [Gr. oion, egg; sphaira, ball] An unfertilized egg.

oostegite n. [Gr. oion, egg; stege, roof] (ARTHRO: Crustacea) In female Peracarida, modified thoracic lamella arising from the coxa of the pereopod that forms a pouch (marsupium) for brooding embryos.

oostegopod n. [Gr. oion, egg; stege, roof; pous, foot] (ARTHRO: Crustacea) 1. Thoracic limb bearing an oostegite. 2. An appendage of the genital somite that forms a brood pouch in some Branchiopoda.

ootheca n.; pl. -cae [Gr. oion, egg; theke, case] (ARTHRO: In-secta) The covering or case over an egg or egg mass.

ootid n. [Gr. oion, egg; eidos, form] One of the four meiotic products arising in oogenesis.

ootocous a. [Gr. oion, egg; tokos, delivery] Egg laying.

ootype n. [Gr. oion, egg; typos, type] (PLATY: Trematoda) A small chamber of the female duct, surrounded by Mehlis' glands, where ducts from a seminal receptacle and vitelline reservoir join.

oozooid n. [Gr. oion, egg; zoon, animal; eidos, form] Any individual developed from an egg, not fragmented or budded. see blastozooid.

opaline a. [L. opalus, opal] Opalescent; bluish or milky white with iridescent luster.

opaque a. [L. opacus, shady] Not transparent or translucent.

open cell (ARTHRO: Insecta) A wing cell that extends to the wing margin.

open coxal cavity (ARTHRO: Insecta) In Coleoptera, when the coxal cavity is only bridged over by the membrane.

open population A population freely exposed to gene flow.

opercular membrane (ARTHRO: Crustacea) In Balanomorpha, a thin, flexible membrane attaching the opercular valves to the sheath; in Verrucomorpha, a membranous hinge.

opercular plug or spot (NEMATA) An escape zone or plug by which a larva leaves the egg membrane.

opercular scar (BRYO: Gymnolaemata) In Cheilostomata, a trace of a cuticular operculum in the frontal closure of the autozooid.

opercular valves (ARTHRO: Crustacea) In sessile Cirripedia, movable plates (2 or 4) occluding the aperture.

operculate a. [L. operculum, lid] Having a lid or operculum.

operculiform a. [L. operculum, lid; forma, shape] Having the shape of a lid or cover.

operculigenous a. [L. operculum, lid; Gr. gennaein, to produce] Producing an operculum.

operculigerous a. [L. operculum, lid; gero, bear] Having an operculum.

operculum n.; pl. opercula [L. operculum, lid] 1. A lid or flaplike cover. 2. (ANN: Polychaeta) In certain sedentary forms, a modified tentacle that closes the tube; in some Spiror-bidae ( Pileolaria and Janua ) enlarges and serves as a brood pouch. 3. (ARTHRO) a. In Chelicerata, a plate covering the opening of the book-lungs of spiders. b. In Crustacea, scuta and terga and sometimes associated membrane forming the apparatus occluding an aperture. c. In Diplo-poda, a plate-like anterior sclerite of the vulva. d. In In-secta, various plates, flaps and specialized structures of the genital segments. 4. (BRYO) A generally uncalcified membrane, hinged on its posterior lip that closes the zooidial orifice. see mandible. 5. (CNID: Hydrozoa) A cover sealing the hydrotheca or gonotheca, may be up to four sections; the lid on the distal end of a nematocyst. 6. (MOLL) A corneous or calcareous structure borne by the foot serving for closure of the aperture. 7. (PLATY) The lid-like opening of an egg-shell.

operon n. [L. opera, work] Adjacent series of nucleiotides that codes for messenger RNA molecules.

opesiule n. [Gr. dim. ope, hole] (BRYO: Gymnolaemata) One of the small notches or pores in a cryptocyst through which the frontal membrane depressor muscles pass.

opesium n.; pl. -ia [Gr. dim. ope, hole] (BRYO: Gymnolae-mata) In Anasca, a large opening below the frontal mem brane bordered by the cryptocyst; functioning as a passageway for the lophophore in some species.

ophiopluteus n. [Gr. ophis, serpent; pluteus, shed] (ECHINOD: Ophiuroidea) Brood larva of Phrynophiurida, with arms edged with cilia, that metamorphose into adults after escape from the bursa through the bursal slits or rupture of the aboral disk.

ophirhabd n. [Gr. ophis, serpent; rhabdos, rod] (PORIF) A megasclere with oxea curved in several places. see euler-habd.

ophiurida n. [Gr. ophis, serpent; oura, tail] (ECHINOD: Ophiuroidea) Simple arms with usually lateral, not verticle movement.

Ophiuroidea, ophiuroids n.; n.pl. [Gr. ophis, serpent; oura, tail; eidos, form] A Class of Echinodermata, with narrow, gradually tapered arms, sharply offset from the central disk, generally 6 or 7 radiate; also called brittle stars, basket stars and snake stars.

ophthalmic a. [Gr. ophthalmos, eye] Pertaining to the eye.

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