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(e.g., in Carchesium ). 
Rostellum : small rostrum ; see Rostrum . 
Rostrum : usually employed in a generalized way, 
with reference to the apical end of an organism’s 
body when it has the appearance of a beak or shows 
a distinctive protuberance of some kind; may bear 
the cytostome , as in the haptorian Chaenea or a 
sucking tube as in the rhynchodians ; the apically 
located perforatorium or boring apparatus might 
better be referred to by this less specific term. 
Rule of Desmodexy : see Desmodexy, Rule of . 
Rules of Nomenclature : see International Code 
of Zoological Nomenclature . 
Saltatorial Cilia : long cilia distributed sparsely 
around the body (e.g., in Halteria ), often stiff or 
heavy when not in motion and used in a quick, 
jerky sort of jumping locomotion. 
Sanguicolous : living in the circulatory system or 
blood of the host. 
Saprobity System : method of classification of 
aqueous habitats and their contained communi-
ties of microorganisms by recognizing both that 
distinct zones exist with respect to degrees of pol-
lution and that these zones provide certain protists 
as indicator organisms with optimal conditions for 
their own growth; see Polysaprobic . 
Sapropelebiotic : see Polysaprobic . 
Sapropelic : see Polysaprobic . 
Saprozoic : type of nutrition in which the organism 
feeds on, takes in, or absorbs food substances in 
the dissolved state from the surrounding medium, 
either by active transport or pinocytosis; this osmo-
trophic mode is to be contrasted with the carni-
vorous, histophagous , holozoic , macrophagous , 
microphagus , or other feeding or nutritional habits 
that essentially involve the ingestion of sizable 
particulate materials, often including whole prey 
Scale : typically a small, sometimes complex struc-
ture, organic or mineralized, and of a shape char-
acteristic for a group; origin, when known, by 
secretion from the Golgi apparatus . 
Scopula (pl. Scopulae ): compound organelle, 
structure or area, at the aboral pole of sessiline 
 peritrichs especially; often cup-shaped with a 
thickened peripheral border or lip comprised of 
scopulary organelles, such as a plaque or field of 
kinetosomes , typically equipped with very short 
and immobile cilia, and pellicular pores ; may 
function directly as a holdfast organelle or, more 
commonly, may be involved in secretion or elabo-
ration of a peduncle or stalk ; see Scopuloid (Sa, 
Fig. 2.11B). 
Scopulary Ciliature : see Scopulary Organelles . 
Scopulary Kinetosomes : see Scopulary 
Organelles . 
Scopulary Organelles : basically the kinetosomes
of the scopula , although their clavate cilia , when 
present, may be included in the definition as well 
as the associated pellicular pores ; various addi-
tional fibrillar and microtubular structures are 
associated with these scopulary kinetosomes, and 
presumably they are also involved in assembly of 
stalk components, when one is present. 
Scopuloid : organelle found at the posterior pole of 
the body of most suctorians ; comprised mainly of 
some kind of pellicular pores , which are presuma-
bly involved in assembly of the sometimes lengthy, 
complex, non-living, never contractile stalk charac-
teristic of suctorians (Sd, Fig. 2.11Cb, 2.11Cc). 
Scutica (pl. Scuticae ): transient “compound” kineto-
somal structure or organelle of scuticociliates ; 
identifiable by its shape, location, and presence at a 
late ontogenetic stage during stomatogenesis ; quite 
conspicuous but generally non-ciliated at the time 
Glossary 51
of its existence, the scutica represents the remainder
of an often much larger stomatogenic field of kineto-
somes located near and slightly to the right of the 
posterior termination of the presumptive infra-
ciliary base of the paroral in both the proter and 
opisthe; typically, manifests a hook-like or whip-
lash configuration (giving it its name), recurving 
back to the right; presumably its kinetosomes have 
arisen from parts of the buccal infraciliature of the 
parental form ; its typical ultimate fate, if it does 
not disappear altogether or become entirely incor-
porated into the paroral, is to persist as a ciliferous 
or non-ciliferous scutico-vestige of varying size 
and shape, in close juxtaposition to the base of the 
paroral and/or at the anterior end of the director-
meridian ; the scutica is thought to be limited to 
members of its namesake, the scuticociliates , but 
its homologue may be present in species of other 
taxa; erroneously spelled scuticus (Sc, Figs. 2.4P, 
2.7i, 2.11Df). 
Scuticobuccokinetal : buccokinetal stomatogenesis
in which the opisthe ’s oral anlage derives either 
from the paroral and the scutica or solely from the 
paroral; found in scuticociliates (Fig. 2.11Df). 
Scutico-field : often used with reference to the 
slightly earlier multi-kinetosomal anlage stage of 
the scutica . 
Scutico-hook : term emphasizing what is the most 
typical appearance of the scutica , its hook-like 
Scutico-kinetosomes : kinetosomes comprising the 
scutica . 
Scutico-vestige : structure visibly remaining in the 
proter and opisthe after the identifiable stage of 
the dynamic scutica has passed; residual field of 
recognizable scutico-kinetosomes . 
Scuticus : a misspelling of scutica . 
Secant System: various lines of convergence of 
kineties in the somatic region ; pre- and postoral 
sutures and the convergence at the antapical pole 
are typical representatives of such systems; suture 
lines may also occur consistently elsewhere, espe-
cially in heavily ciliated organisms that do not 
have simple bipolar kineties ; particularly striking 
in thigmotrichs , astomes , and clevelandellid arm-
phoreans where such stabilized boundary lines or 
aires sécantes are of considerable taxonomic utility;
non-preferred synonym is kinetal suture system 
(SS, Figs. 2.3, 2.7d). 
Sedentary : permanently attached to the substrate, 
which can be sediment, alga, another organism, or 
even the inside of a lorica ; see Sessile . 
Seizing Organ : a special, structured, discrete 
organelle associated with the proboscis of Didinium ; 
now known to be a bundle of discharged toxicysts
and pexicysts used by Didinium in feeding. 
Secondary Meridian : see Ciliary Meridian
(2CM, Fig. 2.7e). 
Secretory Organelle : used in a broader, more 
generalized way to refer to any vesicles, glands, 
pores, adhesive structures, and the like if they are 
involved in some form of secretion; see Ampulla,
Secretory . 
Selfing : see Intraclonal Conjugation . 
SEM : scanning electron microscopy. 
Seme : unit of phylogenetic information; a unit 
character, either ancestral or derived, of high 
information content, usable in reference to any 
structural part or function of an organism, from 
the molecular level up to large and complex unit 
organelles or organellar systems . 
Semi-autonomous : now discarded term for a mode 
of stomatogenesis ; see Buccokinetal . 
Semi-membrane : formerly used as a synonym of the 
undulating membrane ; see Extensor Membrane . 
Sensory Bristle : rather widely applied term to 
many bristles or setae , even when the exact function
is unknown; particularly used to describe both (1) 
the several short rows of clavate cilia in such hap-
torians as Didinium and (2) the non-homologous, 
very short, non-motile cilia occurring in several 
longitudinal rows of pits on the dorsal surface of 
many hypotrichs and stichotrichs ; also called 
dorsal bristles ; the Tastcilien of older literature 
(SB, Figs. 2.3Ae, 2.7l). 
Sensory Organelle : generalized term probably 
often improperly or imprecisely applied to a vari-
ety of structures found in ciliates that may or may 
not actually possess a sensory function; frequently 
implicated organelles include diverse bristles and 
setae , the brosse , other specialized cilia (e.g., caudal 
cilia , clavate cilia

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