Pearlfish Press glossary

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GLOSSARY
The Pearlfish Press Glossary is intended to pertain specifically to the texts that appear in Pearlfish Press publications; it makes no claims to being a comprehensive resource. Further, it is intended to explicate those terms that have particular relevance in the fields of ichthyology, taxonomy, and biological nomenclature, as well as in the aquarium hobby, but it is not intended as a glossary for terms that are in general usage within the English language, however seemingly arcane. Like the other pages within this Website, however, the glossary is subject to continual revision, and will be developed and expanded as appropriate to its popularity among visitors to the site. E-mail comments to brill@pearlfishpress.com

Last updated: December, 2000
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adipose fin	A single small, fleshy, typically rayless fin on the midline of the dorsal surface, between the dorsal and caudal fins. Absent in many fishes, but prominent in characoids, salmonids, catfishes, and certain other groups. Not to be confused with the more anteriorly inserted, rayed dorsal fin(s), also situated on the midline of the dorsal surface
aestivate (also estivate)	To enter a state of dormancy during periods of hot weather, typically summer
aff (abbr.)	Having affinities with. (cf cf)
air bladder	A membranous, gas-filled sac lying between the viscera and vertebral column of fishes that controls buoyancy and in some species also serves as an auxiliary respiratory organ.
allopatric (n. allopatry)	Having non-overlapping geographic ranges. (cf allotopic, sympatric and syntopic)
allotopic (n. allotopy)	Not living together at the same locality. (cf allopatric, sympatric, and syntopic)
anadromous	Living and growing in the sea, but ascending rivers to spawn in freshwater. The sea lamprey, white sturgeon, and many species (or populations) of salmonids are anadromous. (cf diadromous and catadromous)
anal fin	A single fin on the midline of the ventral surface, posterior to the anus. Varies greatly in size, shape, point of insertion, and composition (spines and/or rays) among species.
annual (killifish)	(see annualism)
annualism	A life history characterized by rapid physical and sexual development within an abbreviated life span, in response to the seasonal drying of habitats. In these texts, pertaining to killifishes that occupy ephemeral bodies of water in Africa and South America, some of which live for no more than a few months in nature. (see diapause, peat-spawner, plant-spawner, and temporary pool)
aquarium material	Specimens that have been propagated in captivity, as opposed to having been collected from the wild.
barbel	A cylindrical projection from the mouth area of some fishes, serving a sensory function. Most prominent among (but not unique to) the many different families of catfishes.
benthic	Referring to the substrate or bottom of a body of water. A fish that leads a benthic existence, for example, is a bottom-dwelling species.
binomial (n. and adj.)/binomen (n.)	The scientific name of a species, in two parts: The first part (always beginning with an upper case letter) denotes the genus, and the second part (with very few historical exceptions, all lower case letters) denotes the species. The name of the golden topminnow, Fundulus chrysotus, for example, denotes that the species chrysotus is contained in the genus Fundulus. Since genera are presumed to be monophyletic, the binomial itself implicitly conveys some information on phylogeny. Although it is not strictly required by the International Code of Zoological Nomenclature, it is customary to italicize (alternatively, to underline, boldface, or otherwise distinguish from the surrounding text) both parts of the binomial (or all three parts in the case of a trinomial). (see also epithet)
biodiversity	A diversity of living things, the scope of which can usually be inferred from the context or specific modifiers in/with which the term is used, i.e., "biodiversity" referring to organisms in general, or in more restricted reference to a particular taxonomic group, such as "Corydoras biodiversity," referring to the diversity of a specific taxon.
biogeography	The study of the geographic distribution of living things.
biotope	A region definable by its environmental parameters, and including the community of organisms that it supports; for example, salt marsh, temporary savanna pool, kelp forest, etc.
black water (n.; adj. blackwater)	A non-scientific term applied to water that is lightly to strongly tea-colored as a result of tannins and other organic materials leached from decaying vegetation. Such water is typically very low in pH and total dissolved solids, and thusly support a characteristic fauna, piscine and otherwise, specifically suited to such conditions. Also called "cedar water" within the Pine Barrens of the northeastern United States and along the associated eastern coastal plain.
bottom mop	(see mop [spawning])
bottom-spawner	(see peat-spawner)
brackish water	Water with a salt content that is intermediate between freshwater and sea water.
branchial	Pertaining to the gill, gill chamber, or the associated process of piscine respiration.
brine shrimp	A shrimp in the genus Artemia that inhabits saline and hypersaline waters. It is a staple item among aquarists who feed living foods to their fishes, and in its larval stage is arguably the single most important living food in the entire aquarium hobby and ornamental fish industry. (see nauplii)
catadromous	Living and growing in fresh water, but descending rivers to spawn in the sea. The American eel, Anguilla rostrata, is a catadromous species. (cf anadromous and diadromous)
caudal fin	What would be commonly called the "tail" fin.
caudal peduncle	The part of the body immediately anterior to the caudal fin, between the anal fin and the base of the caudal fin.
cedar water	(see black water)
cepahlic	Of or relating to the head or head region.
cf (abbr.)	Compare to. Used as part of a scientific name, it denotes a tentative identification at the species or subspecies level. The designation Eleotris cf lebretonis, for example, places the specimen in question within the genus Eleotris, suggesting that it be compared to known specimens of the species E. lebretonis. (cf aff)
character	Any trait of an organism; not limited to anatomy (for example, behavioral characters).
chemoreceptor	An anatomical structure that serves the chemical senses by responding to chemical stimuli in the environment. A taste bud, for example, is a type of chemoreceptor.
circumpolar (distribution)	A pattern of distribution in temperate and/or arctic waters more or less surrounding either of the earth's poles. Since the cottids, for example, are well represented throughout northern waters of Europe, Asia, and North America, their collective distribution may properly be referred to as circumpolar in the Northern Hemisphere.
cladistics (n.)	A system of taxonomy based on an assessment of shared derived characters (synapomorphies), in contradistinction to characters which are primitive in relation to the taxonomic level under investigation.
cladogram	The cladistic diagrammatic "tree" of taxonomic relationships.
Code	As used in these pages, a shorthand reference for the International Code of Zoological Nomenclture.
congeneric (adj.; n. congener)	Belonging to the same genus. Apistogramma cacatuoides and A. borelli, for example, are congeneric.
conspecific (n. and adj.)	Belonging to the same species. A fish that is said to be aggressive toward conspecifics, for example, can be expected to fight with members of its own species. (cf heterospecific)
crepuscular	Active at dawn and/or dusk.
cryptic coloration	Coloration and/or markings that blend with a fish's surroundings, rendering it less conspicuous to others; camouflage. Aids prey in avoiding detection, and also aids predators in approaching potential prey.
cryptic species	Morphologically similar species that are distinguished on the basis of genetic (and typically geographic) isolation.
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demersal	Without buoyancy; sinking in the absence of countervailing forces.
description/original description	A description in the vernacular sense (i.e., any enumeration of salient characters, physical and otherwise), although "descriptive" in nature, is not to be confused with the original description of a taxon as the term is used in taxonomic nomenclature. The original description is the earliest published diagnosis of a nominal taxon, providing the characters that define that taxon and distinguish it from other taxa. Criteria to which original descriptions should conform are given by the International Code of Zoological Nomenclature.
diadromous	Referring to a life history characterized by migration between waters of different salinities for growth and spawning. Encompasses both anadromous and catadromous life histories.
diagnosis	As used in taxonomy, the delineation of characters that define a taxon and distinguish it from other taxa.
diapause	A state of arrested development in the eggs of annual killifishes; an adaptation to the extended periods during which their temporary pool habitats become completely dry due to seasonal fluctuations in precipitation, leaving the eggs to develop while buried within the mud substrate. (cf resting eggs)
dichromatic (n. dichromatism)	Exhibiting conspicuous differences in coloration.
dimorphic (n. dimorphism)	Exhibiting conspicuous differences in morphology.
disjunct (distribution)	A distribution that is discontinuous, containing non-overlapping populations.
distal	Fartherst from the point of attachment or from the center. (cf proximal)
distribution, historical/native	The natural distribution of an organism prior to modifications by humans. Such modifications include extirpations (the net effect of which is to reduce the historical range), as well as introductions to waters outside of the historical range (which have the opposite effect of expanding the organism's range beyond its historical range).
dorsal fin(s)	One or more unpaired fins located on the midline of the dorsal surface, exhibiting extreme variation in size, shape, point of insertion, configuration, and composition (rays and/or spines) among taxa. Frequently configured as two discrete fins (for example, in the darters and gobies), rarely three (for example, in certain of the cods). May sometimes consist of freestanding spines unconnected or poorly connected by membranes (for example, in the pinecone fishes and sticklebacks). Not to be confused with the adipose fin, a small, fleshy, rayless fin also situated at the midline on the dorsal surface, posterior to the dorsal fin(s).
endemic	Restricted in distribution to a particular habitat or otherwise circumscribed geographic region. Endemic to Africa's Lake Tanganyika, Cyphotilapia frontosa, for example, is found nowhere else in the world.
epithet (specific or subspecific)	That portion of a scientific binomial or trinomial that refers to the species or subspecies, respectively.
estivate	(see aestivate)
estuary (adj. estuarine)	The biotope formed where fresh water from rivers terminates at and mixes with salt water from the sea or its associated bodies of water. A "buffer zone" where the stream or river currents give way to tidal influence. Such areas are of particular interest because their waters are typically nutrient rich and support a diverse and characteristic assemblage of euryhaline species
euryhaline	Able to tolerate waters over a wide range of salinity. (cf stenohaline; see also estuary)
extant	Living specimens still exist. Usually refers to wild organisms, although the unusual situations in which some killifishes presently find themselves (i.e., extirpated from their natural habitats but surviving in captive populations) often result in qualified statements such as "extinct in the wild," or "extant only in refugia," etc. (cf extinct)
extinct	Living specimens no longer exist. (cf extant)
extirpate	To destroy or eliminate completely. Not necessarily synonymous with extinction, since extirpate may be applied to circumscribed populations within the range of a given species, so it might be said that such-and-such a population has been extirpated, even though the species as a whole is still extant. Although the term extinct may also be applied in a restricted sense, it is more often used to denote the fate of a species as a whole.
family	In the hierarchy of taxonomy, the rank or category below order and above genus. Unlike the names of genera, species, and subspecies, names at the level of family (and above) are not italicized or otherwise distinguish from surrounding text. The name of the family begins with an uppercase letter (for example, "the family Cyprinidae in Ohio..."), whereas references to the members of a particular family are lower cased (for example, "the cyprinids of Ohio ..."). The same conventions of style and usage apply to names used to designate taxa at the level of subfamily. For example, North America's pupfishes and their close relatives are contained in the subfamily Cyprinodontinae; they are referred to as cyprinodontines.
fecund (adj.; n. fecundity)	Prolific; producing or capable of producing many offspring.
floating mop	(see mop [spawning])
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genus (pl. -era)	In the hierarchy of taxonomy, the rank or category below family and above species. The genus name is the first part of the scientific binomial or trinomial. It always begins with an upper case letter, and is always italicized or otherwise distinguished from the surrounding text. The genus may contain any number of species. (see binomial)
gill arches	The supporting bony structures for the gill filaments.
gill raker	Bony projections from the concave anterior surface of the gill arches.
heterocercal	A term applied to the asymmetrical caudal fin of many primitive fishes (for example, paddlefishes and sturgeons), which is characterized by a larger upper lobe into which extend the last few vertebrae.
hetrospecific (n. and adj.)	Belonging to different species. A fish that is said to get along with heterospecific tankmates, for example, can be expected to do well with individuals of different species in captivity. (cf conspecific)
hybrid	The progeny of parents belonging to different species. Does not refer to progeny derived from matings between organisms that are recognized as differing at some level below that of species (for example, between different subspecies, populations, varieties, etc.). (cf intergrade)
hypersaline	Having a salinity greater than that of sea water.
-idae	A suffix indicating a taxon at the level of family. (see annotation accompanying family)
-inae	A suffix indicating a taxon at the level of subfamily. (see annotation accompanying family)
infusoria	A nonspecific reference to a heterogeneous assemblage of microscopic organisms, including but not limited to protozoans; cultured from decomposing organic material by fish breeders as a first food for very small fish fry. The term may also be used even in reference to relatively pure cultures of a single organism (for example, a particular species of Paramecium), and/or to relatively large one-celled organisms that, while small, are nevertheless visible to the unaided eye.
inter-/intra-	Denoting relationships between vs within taxa, respectively. For example, interspecific matings occur between different species of organisms, whereas intraspecific matings occur between organisms of the same species.
intergrade	An organism resulting from the union of parents that differ at a level below that of species. (cf hybrid)
International Code of Zoological Nomenclature	Published by the International Commission on Zoological Nomenclature, the Code consists of "provisions and recommendations designed to enable zoologists...to determine the valid name of a taxon to which an animal belongs at any rank in the [taxonomic] hierarchy" from subspecies through superfamily. Further suggests or stipulates elements of style and usage relating to taxonomic nomenclature.
International Commission on Zoological Nomenclature (abbr. ICZN)	A multinational scientific body, the "fundamental aim [of] which is to provide the maximum universality and continuity in the scientific names of animals," without restraining, regulating, or otherwise infringing upon taxonomic judgments pertaining thereto.
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junior synonym	(see synonym)
killifish	The vernacular term applied to the oviparous members of the order Cyprinodontiformes; i.e., any oviparous cyprinodontiform fish. Historically contained within the single family Cyprinodontidae, but presently construed as comprising a number of families, of which the Cyprinodontidae is only one.
Killifish Master Index (abbr. KMI)	A comprehensive overview of killifish taxonomy published by the American Killifish Association.
KMI	(see Killifish Master Index)
lateral line	A longitudinal row of pored scales along the mid-lateral surface that serves a sensory (tactile) function. Depending on the species, the lateral line may be complete, incomplete, or absent.
local abundance	A condition wherein organisms are found to occur in abundance at a specific locality or within a relatively circumscribed geographic region. Organisms that are found to be locally abundant may be plentiful at a particular site, even though they are rare over the rest of their range.
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micro worm	A species of Nematode in the genus Pangrellus, approximately one-sixteenth of an inch long and smaller than a human hair in diameter, that is easily cultured in a mixture of baby cereal and yeast. Because of its small size and ease of culture, it is a very popular food for young fishes.
monophyletic	Denoting a taxonomic group whose members are all more closely related to each other than to any organism outside of the group. (cf polyphyletic)
monotypic	Denoting a taxon that contains but a single representative. For example, the monotypic genus Amia contains only one species, the bowfin, A. calva. (cf polytypic)
mop (spawning)	A popular artificial spawning medium for killifishes and other species that in nature deposit or scatter adhesive eggs in or over vegetation; made by tightly tying a mass of synthetic yarn into various configurations. Three main types of mops are customarily utilized: 1) A floating or top mop has a cork or Styrofoam float attached; used for species that spawn in the upper water strata and/or near the water's surface; 2) A bottom mop is allowed to sink to the bottom; utilized for species that spawn in vegetation on or near the substrate; 3) A trailing mop is a combination of top and bottom mops, having a float but being long enough to stretch to and extend along the substrate; utilized for species that deposit eggs at all water levels.
mop-spawner	(see plant-spawner)
morphology	The study of the physical characters of an organism; pertaining to its form and structure, or any reference to same.
morph	A phenotypic variant of a species. Not restricted to variations in form and structure, but commonly encompassing variations in coloration as well. (see also polytypic)
mouthbrooder	A fish that incubates its egg orally, often continuing to provide oral protection for the fry post-hatching. The sex of the participating parent varies among taxa. Mouthbrooding as a reproductive strategy has evolved independently in many, distantly related groups of fishes.
nauplii (sing. nauplius)	The larvae of crustaceans, typically encountered in the aquarium literature in specific reference to the newly-hatched stage of the brine shrimp.
nape	The dorsal surface of a fish from the eye to the dorsal fin insertion.
neotropical	Living in tropical regions of the New World.
nomenclature	The standardized rules and provisions for the naming of organisms.
nominal species	A species name that is used independent of any critical determination regarding its validity.
non-annual (n. and adj.)	Referring to organisms--in these texts restricted to killifishes-- that do not exhibit annualism. (see plant-spawner)
nuchal	Pertaining to the nape.
ocellus	A circular or eye-like marking
operculum	The bony covering of the gill chamber; the gill cover.
oviparous	Egglaying. (cf viviparous)
oxbow	A lake that results when erosion cuts off the broad bend of a meandering river.
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panfish	The smaller, less sought-after game fishes that may be caught on hook-and-line; typically applied to the sunfishes in Lepomis and related genera.
patronym	A scientific name derived from the name of a person, almost always in honor or tribute.
peat-diver	(see peat-spawner)
peat-spawner	Usually used in reference to killifishes, denoting species that deposit their eggs within the substrate, which, in the aquarium, is usually composed of boiled peat moss. Typically used interchangeably with the term "bottom-spawner," and usually in reference to annual species. Species that typically dive beneath the substrate to deposit their eggs well below its surface are sometimes more specifically referred to as peat-divers. (see also annualism, plant-spawner, and temporary pool)
pectoral fins	A pair of fins situated on either side of the fish, immediately posterior to the operculum.
pelvic fins	A pair of fins on the ventral surface; inserted on either side of the midline, anterior to the anal fin. Less frequently referred to as ventral fins.
phylogeny	Ancestral (evolutionary) history.
piscine	Of or relating to fishes.
plant-spawner	Usually used in reference to killifishes, denoting species that deposit their eggs off of the substrate, typically, but not necessarily, in vegetation. Although the terms are used so uncritically that it is folly to debate whether or not they are synonymous, it should at least be noted that many hobbyists conflate the terms "plant-spawner," "top-spawner," and "non-annual" when referring to killfishes that lay their eggs in the middle and upper water strata, and/or that produce eggs that do not require drying or have extended incubations times. (see annualism and peat-spawner.)
polyphyletic	Not monophyletic.
polytypic	Denoting a taxon that contains more than one species; also referring to a species that contains more than one representative phenotype within or between populations. Has no standing in the ICZN Code. (cf monotypic; see also morph.)
population	A geographically discrete group of fish that may or may not exhibit corresponding physical, biochemical, or behavioral dissimilarities with other populations. Has no standing in the ICZN Code.
proximal	Nearest to the point of attachment or to the center. (cf distal)
pupfish	A common term for killifishes in the genus Cyprinodon; also very loosely (albeit, infrequently) applied to several obscure related genera such as Cualac and Megupsilon.
resting eggs	Eggs that have entered a state of arrested or slowed development. This term may be used to refer to eggs that have undergone diapause, but it may be used in a less restrictive sense as well to refer to eggs in which development is slowed, but which have not undergone the developmental arrest definitive of diapause. (cf diapause)
riffle	A relatively shallow, swift section of stream flowing over rocks and/or gravel, and typically with a choppy surface.
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scientific name	(see binomial and trinomial)
senior synonym	(see synonym)
siltation	The deposition of silt (very fine aggregate) along the substrate of an aquatic habitat (usually a stream), often with deleterious effects on its inhabitants. Can result from natural phenomena or from human activities such as land development.
spawning mop	(see mop [spawning])
species (abbr. sp.; pl. species, abbr. spp.)	The basic unit in taxonomy, the conceptual underpinnings of which vary among taxonomists, and which is thusly open to wide interpretation. The taxonomic category below genus.
species-complex	A monophyletic group of similar species that nevertheless do not differ enough from others in the genus to warrant separation at the level of genus or subgenus.
speciose	Denoting a taxon that contains many species. For example, Etheostoma is a speciose genus, containing more than one hundred and forty species
standard length	The length of a fish as measured from the tip of its snout to the base of its caudal fin, i.e., to the end of the last vertebra. (cf total length)
stenohaline	Lacking a tolerance for a waters of varying salinity. (cf euryhaline)
subfamily	Taxonomic designation within the family rank, below family.
subgenus (pl. -era)	Taxonomic designation within the genus rank, below genus.
subspecies (abbr. ssp.; pl. subspecies, abbr. sspp.)	Taxonomic designation within the species rank, below species.
swim bladder	(see air bladder)
sympatric	Having overlapping geographic ranges. (cf allopatric, allotopic, and syntopic)
synonym	Two or more names applied to the same taxon. The first established name is the senior synonym; later established names are junior synonyms.
syntopic (n. syntopy)	Living together at the same locality. (cf allopatric, allotopic, and sympatric)
systematics	(see taxonomy)
taxon (pl. -a)	A rank or category in the taxonomic hierarchy, such as family, genus, subgenus, etc.
taxonomy	The discipline concerned with naming and classifying organisms according to their natural relationships, and utilizing standardized rules and provisions.
temporary pools	In areas where rainfall is confined to a fairly circumscribed "rainy season," and absent from a subsequent "dry season," these ephemeral bodies of water may exist for only a few months. The biological constraints imposed by these dichotomous patterns of precipitation are manifest in the unusual life histories of the annual killifishes that inhabit them, most notably, their abbreviated life spans and the extended periods required for development of their eggs. (see annualism, diapause, peat-spawner, and plant-spawner)
top mop	(see mop [spawning])
top-spawner	(see plant-spawner)
total length	The length of a fish as measured from the tip of its snout to the posterior tip of its caudal fin. (cf standard length)
trailing mop	(see mop [spawning])
tribe	A rank or category in the taxonomic hierarchy below subfamily and above genus.
trinomial	The scientific name of a subspecies, in three parts: The first two parts consist of the binomial that denotes the species; the third part (like the specific name, never capitalized) denotes the subspecies. For example, the killifish Fundulopanchax gardneri nigerianus is a subspecies (nigerianus) within the polytypic species Fundulopanchax gardneri. (cf binomial)
trophic	Of or relating to feeding or nutrition.
type(s)	Used alone to loosely refer to the specimen(s) upon which the original description of a species or subspecies is based. More often used as part of a number of compound words to more specifically denote specimens within or apart from the original type series . Among these, the holotype is "the single specimen designated as the name-bearing type of a species or subspecies when it was established, or the single specimen on which such a taxon was based when no type was specified" (International Code of Zoological Nomenclature, 3rd Ed.). Related terms include lectotype, neotype, paratype, and syntype. (see type locale)
type locale (-ity)	The site of collection of the type specimen(s) or series on which the original description of a taxon is based. There is much variation with regard to the specificity with which type locales are designated: Some are very detailed, with precise measurements (for example, from highway mileage markers or other conspicuous landmarks) allowing definitive location of the original site of collection, while others may refer merely to a general area within a state or municipality. (see type)
type series	(see type)
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variety (abbr. var.)	An imprecise designation below the level of species. Has no standing in the ICZN Code.
ventral fins	(see pelvic fins)
viviparous	Livebearing; giving birth to living young. (cf oviparous)
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zoogeography	The study of the geographic distribution of animals.

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