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(End, Fig. 2.12r, 2.12bb). 
Endosprit : old term for the very short suctorial
tentacle of the curious suctorian Cyathodinium . 
Endosymbiont ( of Ciliates ): symbiont , generally 
bacterial or algal in nature, living within the 
cytoplasm or nucleoplasm of a ciliate cell; rang-
ing from kappa particles and other “Greek-letter 
parasites” of Paramecium , bacteria often inti-
mately involved genetically and metabolically 
with their host, to the common zoochlorellae and 
zooxanthellae found widespread among ciliate 
groups; see Xenosome . 
Envelope : used variously; for example, Cortex , 
Lorica , and Nuclear Envelope . 
Epiapokinetal : apokinetal stomatogenesis in 
which the oral anlage develops on the cell surface; 
found in some spirotrichs . 
Epibionts : see Commensal . 
Epilorica (pl. Epiloricae ): additions to protolorica
or paralorica of tintinnids; often appearing as 
supernumerary collars or annuli whose form, struc-
ture, height, and number are variable; see Lorica , 
Paralorica , Protolorica . 
Epiplasm : fibrillar or filamentous pellicular layer 
directly underlying alveoli and/or plasma mem-
brane ; see Lamina corticalis . 
Epistomial Disc : retractable, non-ciliated, vaulted 
center of the peristomial field characteristic of many 
sessiline peritrichs ; in some of the Operculariidae , 
the form of a prominent stalked operculum . 
Epistomial Lip : a cortical ridge that overlies oral 
structures, such as the paroral and its cilia (e.g. in 
some oligotrich spirotrichs and peritrich oligohy-
menophoreans ). 
Ergastoplasm : a generally discarded term, formerly
variously used for the so-called lifeless cell inclu-
sions (i.e., stored fats, starches), for cytoplasmic 
components with affinity for basic dyes, and for a 
form of the endoplasmic reticulum . 
Erratic Kinetosomes : a single or a few kineto-
somes ( ciliferous or non-ciliferous ) that appear to 
have “wandered off” from some larger, more sta-
ble, infraciliary structure or organelle; may appear, 
or be revealable, only at certain stages in the life 
cycle of the organism, becoming involved (in effect 
as an anlage or as a vestige -turned- anlage ) in some 
morphogenetic process, such as stomatogenesis or 
budding (e.g., in suctorians). 
Esophagus : outmoded term not needed and mis-
leading in description of any structure or cavity in 
the oral region. 
Eukaryotic : literally “having a true nucleus”, 
organisms having a unit membrane -bound nucleus
containing chromosomes or chromosome-derived 
gene sequences. 
Eupelagic : see Pelagic . 
Eutrophic : pertaining to an aquatic habitat with 
high primary productivity; high rate of anabolism; 
referring to a habitat rich in minerals and dissolved 
organic nutrients, but often with low oxygen content; 
similar to polysaprobic in some ways, but generally 
not used with regard to pollution; see Oligotrophic . 
Evaginative Budding : type of fission involving 
formation of a temporary brood pouch but in which 
the larval from is not freed within the parental 
form ; in emergence, the entire wall of the pouch 
evaginates and cytokinesis takes place on the out-
side of the parental form; this is the characteristic 
mode of reproduction of members of an entire 
order of suctorians ; in contrast see Endogenous
Budding (Fig. 2.11Cd). 
Evaginogemmy : see Budding and Evaginative 
Budding . 
Evolutionary Series : arrangement of groups of 
organisms in a supposed phylogenetic sequence, 
using some major character or constellation of 
Glossary 29
characters , as a basis for indicating a graded series 
from, for example, ancestral to more derived forms; 
see Orthogenetic Lines for the danger of possibly 
arbitrary and non-phylogenetic sequencing. 
Excystment : the process of leaving a cyst ; see 
Cystation , Encystment . 
Exogemmy : see Exogenous Budding . 
Exogenous Budding : type of single or multiple 
fission taking place essentially on the surface of 
the parental form ; larvae are pinched off singly or 
multiply, and if multiply, either synchronously or 
consecutively; the characteristic mode of reproduc-
tion in certain chonotrichs and in one large group 
of suctorians (Fig. 2.11Cc). 
Explosive Radiation : rapid diversification of forms 
(e.g., into many different taxa at a given level) 
brought about evolutionarily by invasion of a vast 
new and quite different biotope by some “stem” 
group, with subsequent adaptation to the variety 
of specialized habitats and niches thus made avail-
able to the (presumably unopposed) invader; the 
chonotrichs, largely symphorionts on certain crus-
taceans, may well serve as an example of a group 
that has taken advantage of such a situation. 
Explosive Trichocyst : see Trichocyst . 
Expulsion Vesicle : see Contractile Vacuole . 
Expulsion Vesicle Pore : see Contractile Vacuole 
Pore . 
Extensor Membrane : largely disused term refer-
ring to the ciliature of the anterior part of the 
paroral of certain ciliates when it is in an immobile 
state; the paroral cilia, forming a coalesced stiff 
membrane, aid in guiding food particles into the 
oral cavity; called Lachmann’s bristle in peritrichs ; 
at least partially synonymous with another seldom 
used term, semi-membrane. 
External Budding : see Exogenous Budding . 
Extramacronuclear Microtubules : microtubules
that assemble and elongate outside the macro-
nuclear envelope and are used in its division; 
characteristic of the Class HETEROTRICHEA ; see 
Intramacronuclear Microtubules . 
Extrusive Organelle : see Extrusome . 
Extrusome : unit membrane -bound extrusible 
body located in the cortex and assembled by the 
Golgi apparatus ; a generalized term useful in 
referring to various types of probably non-homolo-
gous structures (e.g., clathrocyst , cnidocyst , cono-
cyst , crystallocyst , cyrtocyst , fibrocyst , haptocyst , 
lepido some , mucocyst , pexicyst , rhabdocyst , toxi-
cyst , and trichocyst ); extrusion occurs under 
conditions of appropriate chemical or mechanical 
Exuviotrophic : feeding on tissues or exuvial fluids 
of dead or molted hosts; particularly characteristic 
of one group of apostome ciliates. 
Fascicle : generalized term, but used specifically 
with reference to a group or bundle of suctorial
tentacles on the body of a suctorian , sometimes 
(but not necessarily) born on an actinophore . 
Fibers, Postciliary : see Postciliary Microtubules . 
Fibers, Transverse : see Transverse Microtubules . 
Fibrils : see Microfibrils . 
Fibrocyst : unique trichocyst characteristic of the 
 microthoracine nassophoreans ; fusiform, explo-
sive, and revealing a conspicuous parachute- or 
umbrella-like tip after discharge; also called a 
compound trichocyst. 
Fibrous Trichocyst : see Fibrocyst and Trichocyst . 
Filamentous Annulus (pl. Annuli ): “elastic,” 
expansible binding of fine microfilaments sur-
rounding and considered a part of the rhabdos near 
its proximal (outer) end; allows for the great expan-
sion required by these carnivorous ciliates when 
feeding; said to be continuous with the lamina
corticalis in the vicinity of the corona of various 
Filamentous Reticulum : three-dimensional lat-
tice of kinetosome-associated microfibrils present 
in the wall of the oral cavity or infundibulum
of certain ciliates; often united at condensation 
nodes, giving a striking hexagonal pattern at the 
ultrastructural level (e.g., in some peritrichs ) (FR, 
Fig. 2.6Ac). 
Filaments : any fine fibrous components of the 
cytoskeleton ; see Attachment Organelle ; also an 
extracellular secreted structure used for attachment 
(e.g., Strobilidium ); see Microfilaments . 
30 2. Glossary of Terms and Concepts Useful in Ciliate Systematics
Filial Products : generalized term for (daughter) 
organisms resulting from any mode of ciliate fission ; 
includes tomites and buds , as well as the