The purpose of this glossary is to define terms that are used both in the aquarium hobby as well as in online discussion boards and chat rooms. This glossary will help define most of the terms you come across on Aquarium Fish Home. If you are looking for a term that is not in the glossary, please contact me at john#aquariumfishhome.com(# to @). If the term fits, I will add it to the glossary.

• ABS – Acrylonitrile
• Abyssal plain – The deep ocean floor, an expanse of low relief at depths of 4,000 to 6,000 m
• Abyssopelagic zone – The 4,000 to 6000
• AC – Activated Carbon, or Alternating Current
• Acclimation – Given a change of a single parameter, a readjustment of the physiology of an organism, reaching a new steady state
• Acidic – A water condition which has a pH lower than 7.0 (7.0 being “neutral”)
• Actinic – Actinic03
• Activated Carbon – Solid carbon which is used to adsorb impurities from the water, fresh or marine
• Adipose Fin – This fin most often occurs on characins
• adipose fin – The small fin located between the dorsal fin and the caudal fin
• Aerobic – Oxygen loving or dependent
• AF – Aquarium Frontiers, an electronic magazine
• AFAIK – As far as I know
• AFK – Away from keyboard (also interpreted as A Free Kill in the game Quake)
• AFM – Aquarium Fish Monthly, magazine
• Age structure – The relative abundance of different age classes in a population
• Aggregated spatial distribution – A case where individuals in a space occur in clusters too dense to be explained by chance
• Ahermatypic – Non
• Air Pump – A pump which is used to deliver air to the aquarium
• Airstone – A block (comes in various shapes/sizes) of porous material (eg
• AISI – As I see it
• Albino – Any organism exhibiting deficient pigmentation, and typically having a milky white or translucent skin, and eyes with a deep red pupil and pink or blue iris.”
• Alevin – A juvenile eel.
• Algae – Algae are classified as plants, although they share many characteristics with monerans (fungus)
• ALK – Alkalinity, measure of buffering capacity of water
• Alkaline – A water condition which has a pH higher than 7.0
• Allele – One of several variants that can occupy a locus on a chromosome
• Allopatric speciation – The differentiation of geographically isolated populations into distinct species
• Allozyme – A variant of an enzyme type
• Amensal – Negatively affecting one or several species
• Amino acids – Basic structural unit of proteins
• Ammonia – NH 3
• Ammonia Tower – A biological filtration system which consists of a plastic chamber with a biological filtration media
• Amphipods – Amphipods (meaning “double life”) are tiny shrimp
• Ampullae of Lorenzini – Sensory organs found around the heads of some sharks.
• amyloodinium – Amyloodinium ocellateum is commonly called Oodinium, Marine Velvet, or Saltwater Ick
• Anabantids – A family of fish which possess an auxiliary breathing organ in the head
• Anadromous fish – Fish that spends most of its life feeding in the open ocean but that migrates to spawn in fresh water
• Anaerobic – Meaning, without oxygen
• Anal Fin – A fin found behind the vent of most fish.
• anal fin – Single fin mounted vertically below the fish.
• Andromous – Fish that spend most of their lives in saltwater but migrate into freshwater to spawn.
• Anoxic – Lacking oxygen.
• Anterior – Means located on or near the head or front of an animals body.
• anthostele – The lower part of the polyp, often stiffened, into which the distal portion of the polyp, the anthocodia (which includes the mouth and the eight tenacles) is withdrawn
• Aragonite – This composes the calcium carbonate skeletons of reef coral and some shells
• Arrow worms – Members of the phylum Chaetognatha, a group of planktonic carnivores
• Artemia – A very common food for fresh and marine water fish
• Artemia salina – Brine Shrimp
• AS – algae scrubber
• ASAP – as soon as possible
• asexual reproduction – Asexual means having no sex or sex organs, therefore asexual reproduction would be reproducing by means other than sex.
• Asexual reproduction – Reproduction of the individual without the production of gametes and zygotes
• Assimilation efficiency – The fraction of ingested food that is absorbed and used in metabolism
• Assortative mating – The mating of a given genotype mates with another genotype at a frequency disproportionate to that expected from randomencounter
• Atoll – A horseshoe or circular array of islands, capping a coral reef system perched around an oceanic volcanic seamount
• Attenuation (of light) – Diminution of light intensity; explained, in the ocean, in terms of absorption and scattering
• Auxotrophic algae – Algae requiring a few organically derived substances, such as vitamins, along with dissolved inorganic nutrients forphotosynthesis
• Bacteria – Small single celled organisms from the Moneran kingdom
• Ballast – The power supply for fluorescent and metal halide lighting
• Barbel – Fleshy appendages often found on the mouths of certain fishes such as carp, catfish, and loaches
• barbels – Barbels are the whisker
• Basihyal – A shark’s tongue is called a basihyal
• Bathypelagic – Bathypelagic means of, pertaining to, or living in the deep ocean.
• Bathypelagic zone – The 2,000 to 4,000
• benthic – Benthos and benthic refers to living on or under the substrate at the bottom of the ocean
• Berlin Method – A biological method of filtration which involves only live rock and a protein skimmer
• Berlin Method of Filtration – A biological method of filtration which involves only live rock and a protein skimmer.
• Berm – A broad area of low relief in the upper part of a beach
• Between – habitat comparison
• Biodiversity – See species richness
• Biogenic graded bedding – A regular change of sediment median grain size with depth below the sediment
• Biogenically reworked zone – The depth zone, within a sediment, that is actively burrowed by benthic organisms
• Biological Filtration – One component of a total filtration system
• Bioluminescence – Bioluminescence is the production of light by living organisms
• Biomass – See Standing crop
• Black Water – A very soft, acidic water found in regions of South America (typically)
• Bleach – In aquaculture, bleach (or sodium/calcium hypochlorite) can be used as an algaecide and also to disinfect plants. For plants, use a 5% solution in a bucket and be sure to rinse and dechlorinate when done.
• Blood pigment – A molecule used by an organism to transport oxygen efficiently, usually in a circulatory system (e.g., hemoglobin)
• Bloom – (phytoplankton) A population burst of phytoplankton that remains within a defined part of the water column
• BOD – Biological oxygen demand
• Bohr effect – When blood pH decreases, the ability of hemoglobin to bind to oxygen decreases
• Boreal – Pertaining to the Northern Hemisphere, north temperate zone
• Boring – Capable of penetrating a solid substratum by scraping or chemical dissolution
• Boundary layer – A layer of fluid near a surface, where flow is affected by viscous properties of the fluid
• brackish – water that is neither fresh nor saltwater, but is somewhere in between
• Brackish sea – Semienclosed water body of large extent in which tidal stirring and seaward flow of freshwater do not exert enough of a mixing effect to prevent the body of water from having its own internal circulation pattern
• Brackish Water – This is a zone where salt and fresh water meet
• BRB – Be right back
• Brine Shrimp – (see Artemia salina)
• Browsers – Organisms that feed by scraping thin layers of living organisms from the surface of the substratum (eg., periwinkles feeding on rock
• BTW – By the way
• Bubble Filter – (see Undergravel Filters)
• Bubble Nest – A term used for a nest which is suspended by a weave of tiny air bubbles
• Buffer – A substance used to treat the water and to counteract changes in the pH
• Buffer Agents – A substance used to treat the water and to stabilize changes in the pH
• Byssus Gland – The structure in clams that produces fibrous threads (byssus) that attach the clam to substrate
• Ca – Calcium
• Ca(OH)2 – Calcium hydroxide
• CaCl2 – Calcium chloride
• CaCO3 – Calcium carbonate
• calcyes – plural for calyx
• Cannister Filter – A motorized filter which passes water through an external canister which contains a variety of media
• carapace – A bony or hard shell that covers part or all of an animal
• Carbon Dioxide – A molecule known as CO2, which is a biproduct of respiration
• Carbonate Hardness – A measure of the total amount of both magnesium & calcium carbonates dissolved in water…excluding other salts
• carnivore – Animals who hunt and eat other animals; meat eater
• Carnivorous – Flesh eating.
• Carrying capacity – The total number of individuals of a population that a given environment can sustain
• Cartilaginous Fish – Non
• Catadromous fish. – Fish that spawns in seawater but feed and spends most of its life in estuarine or fresh water
• caudal – The single fin mounted vertically at the rear of the fish
• Caudal Fin – This is the tail fin of a fish.
• Caudal Peduncle – This is the area of the fish where its tails meets its body
• Caudal Penduncle – The long, narrow section which leads into the caudal fin (tail)
• caudal penduncle – The part of the body which attaches the caudal (tailfin) to the body
• CC – Counter current
• CFM – cubic feet per minute
• Chaetognaths – See Arrowworms
• Character displacement – A pattern in which two species with overlapping ecological requirements differ more when they co
• Chemical Filtration – The process of filtering or conditioning the water through chemical substrates, such as activated carbon, zeolite, or peat
• Chemosynthesis – Primary production of organic matter, using various substances instead of light as an energy source; confined to a few groups of microorganisms
• Chiller – A device that functions to cool the water of an aquarium
• Chloramine – A ammonia
• Chlorine – A substance added by municipal water treatment and storage facilities to treat water for the purpose of eliminating bacteria
• Chlorinity – Grams of chloride ions per 1000 grams of seawater
• Chloroplast – In eukaryotic organisms, the cellular organelle in which photosynthesis takes place
• Cichlid – A generic term referring to a group of freshwater fish commonly found in India, South America and Africa
• Cirri – Short, stubby organs located above the eyes of some Saltwater, and Fresh coldwater species
• Cl – Chlorine
• Cladogram – A tree
• Claspers – Claspers are modified organs that enable the two sexes to clasp to one another during mating
• cm/s – cubic meters per second
• CO2 – Carbon dioxide
• CO3 – Carbonate
• Coastal reef – A coral reef occurring near and parallel to a coastline
• coelenterate – an aquatic animal of the Phylum Coelenterata which is characterized by a central mouth usually surrounded by tentacles bearing stinging cells, and no anus; includes sea anemones, corals, and jellyfishes.
• coenenchyma – the tissue of a zoanthid that surrounds the polyps
• Comb jellies – Members of the phylum Ctenophora, a group of gelatinous forms feeding on smaller zooplankton
• comensal – A relationship where two or more different kinds of animals live together and one benefits while the other does not.
• Commensal – Having benefit for one member of a two
• Compensation depth – The depth of the compensation light intensity
• Compensation light intensity – That light intensity at which oxygen evolved from a photosynthesizing organism equals that consumed in its respirationCompetition
• Complex life cycle – A life cycle that consists of several distinct stages (e.g., larva and adult)Conformer
• Concave – Inward curving (used to describe the tail shape)
• conspecific – Refers to animals of the same species.
• Continental drift – Horizontal movement of continents located in plates moving via sea
• Continental Shelf – The continental shelf is the part of the ocean floor next to each of the continents
• Continental shelf – A broad expanse of ocean bottom sloping gently and seaward from the shoreline to the shelf
• Continental slope – See Slope
• Convergence – The contact at the sea surface between two water masses converging, one plunging below the other
• Convex – Outward curving (used to describe the tail shape)
• Copepod – Order of crustaceans found often in the plankton
• Coprophagy – Feeding on fecal materialCoral reef
• Coralline Algae – Desireable encrusting calcium containing algaes
• Corallivore – Any creature that subsits by eating coral
• Corer – Tubular benthic sampling device that is plunged into the bottom in order to obtain a vertically oriented cylindrical sample
• Coriolis effect – The deflection of air or water bodies, relative to the solid earth beneath, as a result of the earth’s eastward rotation
• Counter – illumination
• Countercurrent exchange mechanism – Mechanism by which two vessels are set side by side, with fluid flowing in opposite directions, allowing efficient uptake and retention of heat, oxygen, or gas, depending upon the type of exchanger
• Countershading – Condition of organisms in the water column that are dark
• Courtship Behavior – Instinctive behavior indicating the suitability & willingness to reproduce
• CPU – Central Processing Unit (Computer)
• CPVC – chlorinated poly
• Critical depth – That depth above which total integrated photosynthetic rate equals total integrated respiration of photosynthesizers
• Critical salinity – A salinity of approximately 5 to 8% that marks a minimum of species richness in an estuarine system
• Crustacean – Hard shelled marine animal (eg
• cryptocaryon – Cryptocaryon irritans is a parasitic infection where white spots appear on the body and fins
• CTA – Cellulose triacetate, type of RO membrane
• Ctenophora – See Comb jellies Daily estuary
• Cu – Copper
• CUL – See you later/catch you later
• CUL8R – See you later
• CYANO – Cyanobacteria
• Cyanobacteria – Blue
• cyanobacteria – Cyanobacteria is commonly referred to as red slime algae by hobbyists although it is not really an algae
• Cyclops – Crustaceans in the genus Cyclops
• Daphnia – Crustaceans in the genus Daphnia
• DC – Direct current
• DD – Downdraft, type of protein skimmer
• Deep – scattering layer
• Deep layer – The layer extending from the lowest part of the thermocline to the bottom
• Deionizer – A filtration device used to purify tap water
• Demographic – Referring to numerical characteristics of a population (e.g., population size, age structure)
• Denitrification – The “ideal” completion of the nitrification process…whereby the nitrates are reduced by bacteria (“fab”
• Density – (seawater) Grams of sea water per milliliter of fluid
• Deposit feeder – An organism that derives its nutrition by consuming some fraction of a soft sediment
• Dermal Denticle – Tiny teeth that make up a sharks skin
• Detritivore (Detrivore) – Organisms that feed upon detritus or organic debris. These inhabit the substrate and are generally present to some degree in “live sand.” They not only consume accumulated debris, but also stir the substrate, facilitating O2 potentials and the process of denitrification.
• Detritus – Accumulated, decaying, organic matter and other tiny particles, grains, or refuse.
• DI – Deionisation, type of water purification
• diatom – A diatom is any of a class of microscopic one
• Diatom – Dominant planktonic algal form with siliceous test, occurring as a single cell or as a chain of cells
• Diatom Filter – Filters which use a diatomic filter media
• Diatoms – Single celled protists with silica shells
• Diffusion – The net movement of units of a substance from areas of higher concentration to areas of lower concentration of that substance
• Digestion efficiency – The fraction of living food that does not survive passage through a predator’s gut
• Dinoflagellate – Dominant planktonic algal form, occurring as a single cell, often biflagellate
• Dinoflagellates – Single celled, microscopic, flagella posessing organisms…some photosynthetic, others animal like
• Directional selection – Preferential change in a population, favoring the increase in frequency of one allele over another
• Dissolved organic matter – Dissolved molecules derived from degradation of dead organisms or excretion of molecules synthesized by organisms
• Disturbance – A rapid change in an environment that greatly alters a previously persistent biological community
• Diversity – A parameter describing, in combination, the species richness and evenness of a collection of species
• Diversity gradient – A regular change in diversity correlated with a geographic space or gradient of some environmental factor
• DIY – Do it yourself
• dKH – Degrees of carbonate hardness, measure of alkalinity
• DO – Dissolved oxygen
• DOC – Dissolved organic compound
• DON – dissolved organic nitrogen
• Dorsal Fin – This is the fin that is located along the fishes back.
• dorsal fin – The fin directly on the top of the body (it’s the fin that sticks out of the water when you see a shark)
• Dorsal Surface – The top part of the fish
• Dosing Pump – A pump which serves to maintain a specific water level in an aquarium
• DSB – Deep sand bed
• Egg – Layers
• Egg Spots – Marks located on the rear of the body, frequently on the anal fin of the male
• Ekman circulation – Movement of surface water at an angle from the wind, as a result of the Coriolis effect
• El Niño – Southern Oscillation (ENSO)
• element which is a building block for many organis -
• Emersed – Protruding from or rising above the water, especially pertaining to aquatic plants that grow in environments that are periodically submerged and exposed.
• Emigration – The departure of individuals from a given area
• endemic – Restricted to a particular place
• Endosymbiotic – Being symbiotic and living within the body of an individual of the associated species
• Environmental stress – Variously defined as (a) an environmental change to which an organism cannot acclimate and (b) an environmental change that increases the probability of death
• EPA – environmental protection agency
• EPDM – Ethylene Propylene Diene Monomer
• Epibenthic (epifaunal or epifloral) – Living on the surface of the bottom
• Epidemic spawning – Simultaneous shedding of gametes by a large number of individuals
• Epipelagic zone – The 0
• Epiphyte – Microalgal organism living on a surface (e.g., on a seaweed frond)
• Estuarine flow – Seaward flow of low
• Estuarine realms – Large coastal water regions that have geographic continuity,are bounded landward by a stretch of coastline with fresh
• Estuary – A semienclosed body of water that has a free connection with the open sea and within which seawater is diluted measurably with freshwater that is derived from land drainage
• Euphausiid – Member of an order of holoplanktonic crustacea
• Eutrophic – Water bodies or habitats having high concentrations of nutrients
• Evenness – The component of diversity accounting for the degree to which all species are equal in abundance, as opposed to strong dominance by one or a few species
• Exopthalmia – Protrusion of the eye, usually caused by disease. In fish, this can be caused by gram negative Pseudomonas sp., Aeromonas sp., and Flavobacterium sp. and maybe accompanied by bloody ulceration.
• Exoskeleton – An exoskeleton is a tough, structural body armor made of chitin
• External Filter – A filtration device which is kept outside of the aquarium.
• Faculative Anaerobic Bacteria (FAB): Bacteria capa – In anaerobic conditions, as found in the core of live rock, the FAB obtain O 2 from nitrates, and converts them back to nitrogen & nitrous oxide gases
• FAMA – Freshwater and Marine Aquaria, magazine
• Family – A scientific order of taxonomy which contains genera, or genus
• Fe – Iron
• Fecal pellets – See Pellets
• Fecundity – The number of eggs produced per female per unit time (often: per spawning season)
• FFE – Flying Fish Express, mail order company, United States
• Filmentous Algae – THE plague of marine reef aquarists
• Fingerling – An immature fish, fingerlings are usually larger than Fry
• Fins – An external appendage or “limb” of a fish, used for directing, stabilizing, or propelling it in the water
• FO – Fish only, type of marine aquarium
• Foliose coral – A coral whose skeletal form approximates that of a broad, flattened plate
• Food chain – An abstraction describing the network of feeding relationshipsin a community as a series of links of trophic levels, such as primary producers, herbivores, and primary carnivores
• Food chain efficiency – Amount of energy of some other quantity extracted from a trophic level, divided by the amount of energy produced by the next
• Food web – A network describing the feeding interactions of the species in an area
• Foraminifera – Protozoan group, individuals of which usually secrete a calcareous test; both planktonic and benthic representatives
• Form – Any significant distinguishing taxonomical difference in appearance or shape from the type classification, though not resulting in new species or subspecies recognition
• Founder principle – A small colonizing population is genetically unrepresentative of the source of population
• FOWLR – Fish only with Live Rock, type of reef aquarium
• Freshet – An increase of water flow into an estuary during the late winter or spring, owing to increased precipitation and snow melt in the watershed
• Front – A major discontinuity separating ocean currents and water masses in any combination
• Fry – See Fingerling.
• Fugitive species – A species adapted to colonize newly disturbed habitats Gametophyte
• FW – Freshwater
• FWIW – For what its worth
• FYI – For your information
• FYM – For your misinformation
• GAC – Granular Activated Carbon
• GAL – Gallon
• Gastropod – Gastropods are a class of mollusks that have a sucker
• GBR – Great Barrier Reef
• Generation time – The time period from birth to average age of reproduction
• Genetic drift – Changes in allele frequencies that can be ascribed to random effects
• Genetic locus – A location on a chromosome (possibly of a diploid organism with variants that segregate according to the rules of Mendelian heredity)
• Genetic polymorphism – Presence of several genetically controlled variants in a population
• Genotype – The genetic makeup of an organism, with respect to a given genetic locus, the alleles it carries
• Genus – A scientific order of taxonomy for related species, sharing similar or common characteristics
• genus – In the taxonomy classification, the genus is the category ranking below a family and above a species.
• Geostrophic flow – Movement of water in the oceans as a combined response to the Coriolis effect and gravitational forces created by an uneven sea surface
• Geotactic – Moving in response to the earth’s gravitational field
• Gill – Breathing organ in fish.
• Gill Cover – Operculum
• Gill Rakers – Gill rakers are bristly structures (the bristles are about 4 inches or 10 cm long) in a filter
• GIS – Geographic Information System
• Global warming – Predicted increase in the earth’s oceanic and atmospheric temperature, owing to additions of carbon dioxide to the atmosphere, as a result of human activities
• GMTA – Great minds think alike
• Gonopodia – Plural of gonopodium. See below.
• Gonopodium – The modified anal fin of male live-bearers, such as guppies, which serves as a sex-organ for transferring sperm to the female fish.
• gorgonian – A Gorgonian is a tropical or subtropical octocoral with upright branchy plant
• GPD – gallons per day
• GPH – Gallons per hour
• GPM – gallons per minute
• GPS – Global Positioning System
• Grab – Benthic sampling device with two or more curved metal plates designed to converge when the sampler hits bottom and grab a specified volume of bottom sediment
• Gravid – A pregnant female fish
• Grazer – A predator that consumes organisms far smaller than itself (e.g., copepods graze on diatoms)
• Greenhouse effect – Carbon dioxide traps solar
• Gregarious settling – Settlement of larvae that have been attracted to members of their own species
• Gross primary productivity – The total primary production, not counting the loss in respiration
• Guild – A group of species, possibly unrelated taxonomically, that exploit overlapping resources
• Gut – The intestines of a fish
• Gyre – Major cyclonic surface current systems in the oceans
• H2S – hydrogen sulfide
• Hair Algae – (see Filamentous Algae)
• Halocline – Depth zone within which salinity changes maximally
• Hard Water – A water condition which has a lot of dissolved salts
• Hardy – Weinberg law
• HCO3 – Hydrogen carbonate
• head and lateral line erosion – Also known as hole
• Herbivore – Any plant eating animal
• herbivore – Animals whose diet consists mainly of vegetable matter.
• Heritable character – A morphological character whose given state can be explained partially in terms of the genotype of the individualHermaphrodite
• Hermaphrodite – Having the organs of both sexes.
• hermaphrodite – Refers to both male and female in the same organism.
• hermatypic – Refers organisms that contain zooxanthellae
• Hermatypic – Reef
• Heterotrophic algae – Algae that take up organic molecules as a primary source of nutrition
• Heterozygote – With respect to a given genetic locus, a diploid individual carrying two different alleles
• HID – High intensity discharge lighting (MH&MV)
• Highly stratified estuary – An estuary having a distinct surface layer of fresh or very
• Histogram – A multiple
• HO – High output fluorescent light
• HO lighting – High Output fluorescent lighting
• Holoplankton – Organisms spending all their life in the water column and not on or in the sea bed
• Homeotherm – An organism that regulates its body temperature despite changes in the external environmental temperature
• Homozygote – With respect to a given genetic locus, a diploid individual carrying two identical alleles
• HTH – Hope this helps
• Hydrogen Sulfide – H 2 S
• Hydrographic – Referring to the arrangement and movement of bodies of water, such as currents and water masses
• hydrometer – A Hydrometer is an instrument used to determine the specific gravity of a fluid
• Hydrophyte – A true aquatic plant, or one that is normally fully submerged, lacking stomatae or a thick cuticle surface on its leaves and the circulatory system and structural support in its stems, normally present in terrestrial or emersed plants.
• Hydrothermal vents – Sites in the deep ocean floor where hot, sulfur
• Hypothesis – A refutable statement about one or a series of phenomena
• I – Iodide
• I2 – Iodine
• IA – Inland Aquatics, store, detrivore kits
• Ichthyology – The study of Fish
• ID – Identity
• IE – Internet Explorer, WWW browser
• IME – In my experience
• IMEO – In my expert opinion
• IMHO – In my humble/honest opinion
• IMNSHO – In my not so humble/honest opinion
• IMO – In my opinion
• Infaunal – Living within a soft sediment and being large enough to displace sedimentary grains
• Infusorians – Rotifers, protozoans and other minute organisms that frequently form a fry’s first food stuff
• Internal Filter – A filtration unit which is kept and functions inside the aquarium
• Interspecific competition – Condition in which one species’ exploitation of a limiting resource negatively affects another species
• Interstitial – Living in the pore spaces among sedimentary grains in a soft sediment
• invertebrate – Commonly called inverts by many in the hobby
• Invertebrates – Animals without backbones
• IO3 – Iodate
• Iodine – A diatomic molecule consisting of two iodine elements
• IOW – In other words
• IPSF – Indo Pacific Sea Farms, store, detrivore kits
• IR – Infrared, type of light with longer wavelength than visible light
• IRC – Internet relay chat
• Isotonic – Having the same overall concentration of dissolved substances as a given reference solution
• ISP – Internet service provider
• KALK – Kalkwasser, German for calcium hydroxide solution or limewater
• Kalkwasser – Ca(HO) 2
• kalkwasser – German word meaning calcium water, kalkwasser is a mixture of calcium hydroxide in water
• Keystone species – A predator at the top of a food web, or discrete subweb, capable of consuming organisms of more than one trophic level beneath it
• kg/L – kilograms per liter
• KI – Potassium iodide
• Killifish – A very beautiful group of fish in the family, Cyprinodontidae
• KISS – Keep it simple stupid
• KMnO4 – The chemical formula for potassium permanganate. See below.
• Krill – A type of small, open ocean shrimp found in dense schools in cool and temperate waters.
• L8R – Later
• Labyrinth Fish – Members of the family Anabantidae
• Labyrinth Organ – This is an organ that enables fish to obtain oxygen from the air
• Laminar flow – The movement of a fluid where movement of the entire fluid is regular and with parallel streamlines.
• Larva – A discrete stage in many species, beginning with zygote formation and ending with metamorphosis
• Larvacea – A group of planktonic tunicates that secrete a gelatinous house, used to strain unsuitable particles (large particles are rejected)
• Larvae – Immature but active stage of growth.
• Lateral Band – A darkish colored longitudinal band along the sides of a fish
• Lateral Line – A row of sensory receptors along the flanks of some fish.
• lateral line – The lateral line is a line of perforated scales along the flanks of a fish which lead to a pressure
• Leaching – The loss of soluble material from decaying organisms
• Lecithotrophic larva – A planktonic
• Leeward – The side of an island opposite from the one facing a persistent wind
• LFS – Local fish store
• LHS – Local hardware store
• Life table – A table summarizing statistics of a population, such as survival and reproduction, all broken down according to age classes
• Litter – Accumulations of dead leaves in various states of fragmentation and decomposition
• Littoral – A coastal region or shore of an ocean or lake. It also refers to the region between the limits of high and low tide or the shallows near the shore of a body of water.
• Live Rock – A term used to describe the associated strains of bacteria on calcareous (primarily) rock which has been removed from part of a tropical reef
• Livebearer – A fish which gives birth to live young
• LMK – Let Me Know
• Locus – See Genetic locus
• Logistic population growth – Population growth that is modulated by the population size relative to carrying capacity
• LOL – Laughing out loud, or Lots of Luck
• Longshore current – A current moving parallel to a shoreline
• LPD – liter per day
• LPH – Litres per hour
• LPM – liters per minute
• LPS – Large polyped Scleractinian (stoney) coral
• LR – Live rock
• LS – Live Sand
• LSV – Living Sand Bed
• LT – Litre
• Ma – miliamps
• MACNA – Marine Aquaria Conference of North America, held annually
• Macrobenthos – (macrofauna or macroflora) Benthic organisms (animals or plants) whose shortest dimension is greater than or equal to 0.5 mm
• Macrofauna – Animals whose shortest dimension is greater than or equal to 0.5 mm
• Macrophyte – An individual alga large enough to be seen easily with the unaided eye
• Macroplankton – Planktonic organisms that are 200
• Mainstream flow – The flow in a part of the fluid (e.g., in a tidal creek) that is well above the bottom or well away from a surface and essentially not under the influence of the boundary layer (see boundary layer).
• Mangel – See Mangrove forest.
• Mangrove forest – A shoreline ecosystem dominated by mangrove trees, with associated mud flats.
• Mantle – Large, pigmented fleshy portion of tridacnid clams that is exposed to the light by gaping of the shell valves
• Marine protected area – A conservation geographic unit designed to protect crucial communities and to provide reproductive reserves for fisheries that hopefully will disperse over wider areas
• Marine snow – Fragile organic aggregates, resulting from the collision of dissolved organic molecules or from the degradation of gelatinous substances such as larvacean houses
• MASNA – Marine Aquarium Society of North America
• Mechanical Filtration – Filtration whose primary function is to eliminate particlulate matter from the water
• Megaplankton – Planktonic organisms that are greater than or equal to 2000 micrometers in size
• Meiobenthos (meiofauna or meioflora) – Benthic organisms (animals or plants) whose shortest dimension is less than 0.5 mm but greater than or equal to 0.1 mm
• Meiofauna – Animals whose shortest dimension is less than 0.5 mm but greater than or equal to 0.1 mm
• MEQ/L – Milli
• Meroplankton – Organisms that spend part of their time in the plankton but also spend time in the benthos (e.g., planktonic larvae of benthic invertebrates)
• Mesopelagic – The 150
• Metabolic rate – The overall rate of biochemical reactions in an organism
• Metal Halide Lighting – Metal halide is considered by many to be a best method of lighting reef tanks
• Metal Halide Lighting – Considered by many to be the best method of lighting reef tanks
• Metamorphosis – Major developmental change as the larva develops into an immature adult
• Metapopulation – A group of interconnected subpopulations, usually of subequal size
• Mg – Magnesium
• mg/L – Milligrams per litre. 1 mg/L = 1ppm (part per million)
• MH – Metal halide, lighting
• Microbenthos – (microfauna or microflora) Benthic organisms (animals or plants) whose shortest dimension is less than 0.1 mm
• Microfauna – Animals whose shortest dimension is less than 0.1 mm
• Milt – This is male fish sperm.
• mimicry – When an animal mimics, or copies the appearance of another animal in order to gain an advantage, like camouflage or a better defense
• Mixing depth – The water depth to which wind energy evenly mixes the water column
• Mixoplankton – Planktonic organisms that can be classified at several trophic levels
• MO – Mail order
• Moderately stratified estuary – An estuary in which seaward flow of surface low
• Mollusc – Soft
• Monophyletic – Refers to a group of species that all have a single common ancestral species
• Mouth Brooder – Fish, usually females, which protect unhatched eggs in the mouth or buccal cavity
• MTS – Malaysian Trumpet Snail
• Mucous – bag suspension feeder
• Mulm – (see Detritus)
• Mutualism – An interaction between two species in which both derive some benefit
• Mutualistic – Conferring reciprocal benefit to individuals of two different associated species
• Mv – milivolts
• MV – Mercury vapor, type of HID lighting
• Na – Sodium
• NaCO3 – Sodium carbonate
• Nanoplankton – Planktonic organisms that are 2
• NaOH – Sodium hydroxide
• Native Fish – Those species which occur naturally in an area.
• Neap tides – Tides occurring when the vertical range is minimal
• Nekton – Organisms with swimming abilities that permit them to move actively through the water column and to move against currents
• nematocysts – The cells at the tip of an anemones’ (corals) tentacles which “sting” when touched.
• Neritic – Seawater environments landward of the shelf
• Net primary productivity – Total primary production, minus the amount consumed in respiration
• Neuston – Planktonic organisms associated with the air
• NH3 – Ammonia
• NH4 – Ammonium
• Niche – A general term referring to the range of environmental space occupied by a species
• Niche overlap – An overlap in resource requirements by two species
• Nictitating Membrane – The white inner eyelid of some sharks which shuts to protect the eye while fighting and feeding.
• Nitrate – NO 3
• Nitrification – This is the process by which bacteria oxidize lethal ammonia into relatively harmless nitrates by going through 2 different stages. The first stage bacteria change NH3/NH4+ (ammonia/ammonium – toxic to fish) to NO2- (nitrite – toxic to fish). The second stage bacteria convert NO2- to NO3- (nitrate – harmless).
• Nitrifying Bacteria – Principally, Nitrobacter and Nitrosomonas
• Nitrites – NO 2
• Nitrogen Cycle – (see Nitrification)
• Nitrogen fixation – The conversion of gaseous nitrogen to nitrate by specialized bacteria.
• NNR – Natural nitrate reduction, reef setup technique
• NO – Normal output fluorescent light
• No – take Reserves
• NO2 – NitrIte
• NO3 – NitrAte
• NP – No problem
• NRN – No reply necessary
• NS – Netscape, WWW browser
• NSW – Natural seawater
• Nuchal Hump – This is an enlarged hump on some species of male fish.
• Nuisance bloom – A rapid increase of one or only a few species of phytoplankton, resulting in densities high enough to cause discoloration of the surface water, possible increase of toxins, and degradation of water quality aspects such as dissolved oxygen
• Nutrient cycling – The pattern of transfer of nutrients between the components of a food web
• Nutrients – Those constituents required by organisms for maintenance and growth (we use this term in this book in application to plants)
• O2 – Oxygen
• OBTW – Oh by the way
• Oceanic – Associated with sea
• Oceanic ridge – A sinuous ridge rising from the deep
• octocoral – Octocorals have eight tentacles on each polyp
• Oligotrophic – Refers to water bodies or habitats with low concentrations of nutrients
• omnivore – Animals who eat both meat and vegetables like marine angelfish.
• Omnivorous – Eating all foods, both plant and flesh.
• Omnivory – Being able to feed in more than one distinct way (e.g., an organism capable of carnivory and herbivory)
• Operculum – This is the hard gill cover or the gill plates.
• Optimal foraging theory – A theory designed to predict the foraging behavior that maximizes food intake per unit time
• Organic – Deriving from living organisms
• Organic nutrients – Nutrients in the form of molecules synthesized by or originating from other organisms
• ORP – Oxidative redox potential
• Osmoconformer – An organism whose body fluids change directly with a change in the concentrations of dissolved ions in the external medium
• Osmoregulator – An organism that regulates the concentration of dissolved ions in its body fluids irrespective of changes in the external medium
• Osmosis – The movement of pure water across a membrane from a compartment with relatively low dissolved ions to a compartment with higher concentrations of dissolved ions
• Otholiths – A pair of bones in the inner ear of fish which exhibit growth rings
• OTOH – On the other hand
• Outwelling – The outflow of nutrients from an estuary or salt
• Overdominance – Selection favoring heterozygotes
• oviparous – Producing eggs which are fertilized, develop and hatch outside the body.
• Ovipositor – A tube, extended from the anal area of a female fish, used to deposit eggs
• ovoviviparous – Producing eggs (usually with yolk) that are fertilized internally
• Oxygen dissociation curve – A curve showing the percent saturation of a blood pigment, such as hemoglobin, as a function of oxygen concentration of the fluid
• Oxygen minimum layer – A depth zone, usually below the thermocline, in which dissolved oxygen is minimal
• Oxygen technique (primary productivity) – The estimation of primary productivity by the measurement of the rate of oxygen increase
• Ozone – O 3
• PA – Premium Aquatics, mail order company, U.S
• Paludarium – A tank environment that includes both land and water (part terrarium, part aquarium) for animals that are amphibious, or for a shared habitat of land-dwelling and aquatic creatures. This also includes littoral environments or those simulating the edge of brackish waterway or salt marsh.
• Parapatric speciation – The differentiation into distinct species of populations experiencing some gene flow
• Parasite – An organism living on or in, and negatively affecting, another organism
• Particulate organic matter – Particulate material in the sea derived from the decomposition of the nonmineral constituents of living organisms
• Patchiness – A condition in which organisms occur in aggregations
• PC – Power compact, high intensity fluorescent light
• Pearling – The production of oxygen bubbles on plant surfaces during active photosynthesis due to stimulation by light. The tiny oxygen bubbles resemble small “pearls.”
• Peat – Peat moss is used to soften water and to decrease (acidify) pH
• Pectoral Fins – Pectoral fins are the paired fins located behind the head and on the lower side of the fish.
• Peduncle – Where the body of the fish and the tail meet.
• pelagic – Refers to living in the water of the ocean above the bottom
• Pellets – Compacted aggregations of particles resulting either from egestion (fecal pellets) or from burrow
• Pelvic Fins – These are the fins that are located just forward of the anal fin.
• Penetration anchor – In hydraulically burrowing organisms, any device used to penetrate and gain an initial purchase on the sediment so that the body can be thrust in farther
• Peptides – Chains of amino acids; often portions of a protein molecule
• pH – Measure of the concentration of hydrogen ions
• PH – Powerhead, water circulator
• Pharyngeal Teeth – Sometimes known as false
• Phenotypic plasticity – The capacity of an individual to produce different phenotypes under different conditions
• Phi scale – Scale used for measuring the grain size of sediments
• Phosphate – Although an important trace element in the marine tank, excessive quantities can result in rampant algae growth! Control of phosphates is critical to maintaining a successful reef aquarium
• Phosphorous – An important trace element in the marine tank
• Photic zone – The depth zone in the ocean extending from the surface to that depth permitting photosynthesis
• Photoperiod – Refers to the number of sequential hours that light and dark are applied to an aquarium
• Photorespiration – Enhanced respiration of plants in the light relative to dark respiration
• Photosynthate – A substance synthesized in the process of photosynthesis
• photosynthetic – The process by which organisms, usually plants, use the energy contained in light, usually sunlight.
• Photosynthetic quotient – In photosynthesis, the moles of oxygen produced, divided by the moles of carbon dioxide assimilated
• Photosynthetic rate – The rate of conversion of dissolved carbon dioxide and bicarbonate ion to photosynthetic product
• Phototactic – Moving in response to light
• Physiological race – A geographically defined population of a species that is physiologically distinct from other populations
• Phytoplankton – The photosynthesizing organisms residing in the plankton
• pinnate – Feather like
• Pl*co – Another name for Pleco, or Plecostomus
• Planktivorous – Feeding on planktonic organisms
• Plankton – Myriad forms of tiny marine life.
• plankton – Plankton are the drifters of the sea
• Planktotrophic larva – Planktonic
• Planula – The planktonic larval form produced by scleractinian corals and coelenterates
• Plate – Major section of the earth’s crust, bounded by such features as mid
• Pleistocene – Period of time, going back to approximately 2 million years before the present, in which alternating periods of glaciation and deglaciation have dominated the earth’s climate
• Pleuston – Refers to plankton that have a float protruding above the sea surface, such as the Portugese man
• PLS/PLZ – Please
• PO4 – Phosphate
• Poikilotherm – An organism whose body temperature is identical to that of the external environment
• polyp – A polyp is the living unit of a coral.
• Polyp – An individual of a solitary coelenterate or one member of a coelenterate colony
• Polyphyletic – Refers to a group of species that do not have one common ancestor species
• Population density – Number of individuals per unit area or volume
• Porifera – The phylum comprising the sponges.
• Potassium Permanganate (KMnO4) – Potassium permanganate is a strong oxidizer and disinfectant used to maintain water quality, eliminate harmful organisms, and disinfect plants. In aquaculture, a 5ppm (mg/L) solution for 10 minutes at room temperature should be effective at killing snail eggs and many other harmful organisms that exists on plants and other “found” tank ornaments (rocks, etc.).
• Powerfilter – Powerfilter is a common name used to describe any type of filtration that is powered by an electric pump to pass water through filter media
• Powerhead – A power head is a small, submersible pump which is used to power UGF’s (undergravel filters), and to provide general circulation and turbulence
• ppm – Parts per million, equivalent to mg/L(milligrams per litre) 1 ppm = 1 mg/L.
• PPT – parts per thousand
• predaceous – This means the animal will hunt and eat other animals
• Predation – The consumption of one organism by another
• Predator – An organism that consumes another living organism (carnivores and herbivores are both predators by this definition)
• Prefilter – A simple mechanical filter, designed to remove large particles as the water leaves the tank
• Primary producer – An organism capable of using the energy derived from light or a chemical substance in order to manufacture energy
• Primary production – The production of living matter by photosynthesizing organisms or by chemosynthesizing organisms
• Protein polymorphism – Presence of several variants of a protein of a given type (e.g., a certain enzyme, such as carboxylase) in a population
• Protein Skimmer – Also known as a Foam Fractionator
• protozoan – A protozoan is a single
• Province – A geographically defined area with a characteristic set of species or characteristic percentage representation by given species
• Pseudofeces – Material rejected by suspension feeders or deposit feeders as potential food before entering the gut
• PSI – Pounds per square inch
• Pteropods – Group of holoplanktonic gastropods
• PVC – Poly vinyl chloride, used for piping/plumbing
• Pycnocline – Depth zone within which sea
• Q10 – Increase of metabolic rate with an increase of 10ºC
• Quantitative genetics – The study of the genetic basis of traits, usually explained in terms of the interaction of a group of genes with the environment
• Radiocarbon technique (primary productivity) – The estimation of primary productivity by the measurement of radiocarbon uptake
• Radiolaria – Protistan phylum, whose members are planktonic and secrete an often elaborate siliceous test
• RAMR – Usenet newsgroup rec.aquaria.marine.reefs
• Random spatial distribution – Situation in which individuals are randomly distributed in a space; probability of an individual’s being located at any given point is the same irrespective of location in the space
• Ray – The bones which make up the tissue supporting skeleton in the fins
• Rays – Fin rays are the bony support structures of the fins on a fish
• Reactor – A device used to force a specialized controlled reaction with a substance
• Recruitment – The residue of those larvae that have: (1) dispersed; (2) settled at the adult site; (3) made some final movements toward the adult habitat; (4) metamorphosed successfully, and (5) survived to be detected by the observer
• red Slime – see cyanobacteria.
• Red tide – A dense outburst of phytoplankton (usually dinoflagellates) often coloring water red brown
• Redox – Reduction
• Refuge – A device by which an individual can avoid predation
• Regulator – An organism that can maintain constant some aspect of its physiology (e.g., body temperature) constant despite different and changing properties of the external environment
• Renewable resource – A resource that can be regenerated (e.g., a growing diatom population that is being exploited by a copepod)
• Reproductive effort – The fraction of assimilated nutrients that are devoted to reproductive behavior and gamete production
• Resource – A commodity that is required by an organism and is potentially in short supply
• Respiration – Consumption of oxygen in the process of aerobic metabolism
• Respiratory pigment – A molecule, polymer, or other complex adapted to bind and transport oxygen efficiently, usually in a circulatory system (e.g., hemoglobin)
• Respiratory quotient – The ratio of moles of carbon dioxide produced to oxygen consumed in respiration
• Rete mirabile – A countercurrent exchange structure of capillaries that allows gas uptake in a fish swim bladder
• Reverse Bohr effect – Effect that occurs when lactate builds up in the blood of certain invertebrates and pH decreases, increasing the affinity of hemocyanin for oxygen
• Reverse Osmosis – Also refered to as RO units
• Reynolds number – A number that represents the relative importance of viscous forces and inertial forces in a fluid
• Rip current – A concentrated rapid current moving offshore from a beach fronting a longshore current
• Rise – Bottom of low relief at the base of the continental slope
• RO – Not propper but sometimes refers to regular output
• RO/DI – Reverse osmosis, followed by deionisation, type of water purification
• Roe – Fish eggs.
• ROFL – Rolling on the floor laughing
• ROFLOL – Rolling on the floor laughing out loud
• ROTFL – Rolling on the floor laughing
• ROTFLMAO – Rolling on the floor laughing my *** off
• ROV – Abbreviation for remotely operated vehicle, usually a submersible tethered to a ship, with facilities for video, remote sampling by grabbing arms, and precise navigation
• RTN – Rapid tissue necrosis
• RUGF – Reverse flow undergravel filter
• SAL – Salinity
• Salinity – Number of grams of dissolved salts in 1,000 g of seawater
• Salps – A group of pelagic tunicates (phylum Urochordata), either colonial or solitary, with buccal and atrial siphons on opposite sides of the body
• Salt – A common term which chemically refers to a cation and an anion compound
• Salt marsh – A coastal habitat consisting of salt
• Sashimi – Japanese
• Scale – The small bony plates that cover most fish
• Scalpel – A spine which is located on the tail base (caudel peduncle) of surgeonfish (tangs)
• Scalpel Marking – A spine which is located on the tail base (caudel peduncle) of surgeonfish (tangs)
• Scavenger – An organism that feeds on dead or decomposing animals or macrophytes
• School – A term used to identify a group of fish moving together.
• Scleractinia – Order of coelenterates, usually producing calcareous skeletons with hexameral symmetry
• Scope for growth – The surplus of energy available for growth beyond that required for maintenance
• Scute – A type of scale most common in catfish, modified to resemble large armored plates
• Scutes – Sharp, modified scales along the lateral lines of some fish (eg
• Scyphozoa – the true jellyfish, members of the phylum Cnidaria
• Sea – floor spreading
• Seasonal estuary – An estuary in which salinity at any one geographic point changes seasonally (e.g., decreases during the spring melt)
• Seaward – Side of an island that faces the direction of wave action generated either by winds or by currents generated by more indirect forces
• Secondary production – The production of living material per unit area (or volume) per unit time by herbivores
• Selection – A change in allele frequency over time in a population
• Sequential hermaphrodite – An individual that sequentially produces male and then female gametes or vice versa
• sessile – Sessile means the organism is attached to the substrate at the bottom of the ocean and therefore cannot move around
• Sessile – Immobile because of an attachment to a substratum
• Seston – Particulate matter suspended in seawater
• Setules – Chitinous projections from copepod maxillipeds that trap food particles
• Sexual Dichromatism – Difference in coloration between males and females within a species…Not relating to Form
• Sexual Dimorphism – Difference in shape & size between males and females within a species…Not relating to Form
• SG – Specific gravity
• Shelf – slope break
• Shellfish – See Mollusc.
• SHO – Super high output fluorescent light, equivalent to power compact fluorescent
• Si – Silicon
• Sibling species – Closely related species that are so similar that they are nearly indistinguishable morphologically
• Sigma – Parameter expressing the seawater density: and equal to 1 minus the density of seawater, measured at a given temperature and at a pressure of l atmosphere
• Silicon – A trace element in the marine system
• SiO2 – Silicon dioxide
• Siphon – The inhalent and exhalent siphons of tridacnid clams are used to allow for gas exchange and to expel wastes.
• Siphonophores – A group of specialized hydrozoan cnidarians, consisting of large planktonic polymorphic colonies
• SITD – Still in the dark
• Sled – A benthic sampling device designed to slide along the sediment surface, digging into the bottom to a depth of at most a few centimeters
• Snow – See marine snow
• SO – Significant other
• Sodium/Calcium Hypochlorite – Household bleach (see above.)
• Soft Water – A water quality, characterized by containing very small amounts of dissolved salts
• Somatic growth – Growth of the body, exclusive of gametes
• Sorting (of a sediment) – The range of scatter of particle sizes about the median grain size of a sediment
• Space limited – Description of a situation in which space is a limiting resource
• Spatial autocorrelation – A situation in which some parameter at any location (e.g., population density) can be predicted through a knowledge of the values of the parameter in other locations
• Spatial distribution – The arrangement of individuals in a space
• Spawning – A term that refers to the act of fish reproduction
• Speciation – The process of formation of new species
• Species – This is the scientific, taxonomic name of a living thing.
• Species richness – The number of species in an area or biological collection
• Specific Gravity – A scientific term which is used to describe the salt content of water
• specific gravity – As a hobbyist definition, specific gravity is the amount of salt in the water
• Sporophyte – Diploid stage in the life cycle of a plant
• Spring diatom increase – The major rapid population increase of diatoms, occurring in the spring in temperate
• Spring tides – Fortnightly tides occurring when the vertical tidal range is maximal
• SPS – Small polyped Scleractinian (stoney) coral
• Sr – Strontium
• Stability – time hypothesis
• Standing crop – The amount of living material per unit area or volume; may be expressed as grams of carbon, total dry weight, and so on
• Stock recruitment models – Fishery models that predict the amount of juvenile recruitment as a function of the parent stock
• Strain – A variety of a certain species
• Stratification – In benthos, the presence of different infaunal species at distinct respective horizons below the sediment
• Strontium – A trace element which is essential to the growth of reef coral
• Subspecies – A scientific breakdown of organisms of a particular species
• Substrate – The land below any water body
• Substratum – The many different layers of substrates found in nature or in the aquarium
• Subtropical – Refers to the portion of the temperate zone closest to the equator
• Succession – A predictable ordering of a dominance of a species or groups of species following the opening of an environment to biological colonization
• Sump – A collection container mainly used in marine tanks
• Surface layer – The layer of the ocean extending from the surface to a depth above which the ocean is homogeneous due to wind mixing
• Survivorship curve – The curve describing changes of mortality rate as a function of age
• Suspension feeder – An organism that feeds by capturing particles suspended in the water column
• SW – Saltwater/seawater
• Swash rider – Invertebrate that can migrate up and down shore with the rising and falling tide, in order to maintain station at a level that is moist but not overly washed by the waves
• sweeper tentacle/polyp – A coral tentacle or polyp that has an increased number of nematocysts and elongates in order to ‘sting’ neighboring corals and sessile invertebrates
• Swim Bladder – usually an air or fat filled organ that is used by fish to maintain neutral water buoyancy
• symbiotic – A relationship where two or more different kinds of animals live together and both benefit in some way from the other’s company
• TAT – Thiel Aqua Tech, mail order company, United States
• taxonomy – The classification of organisms in an ordered system that indicates natural relationships.
• TBS – Tampa Bay Saltwater, mail order company, United States
• TDS – total dissolved solids
• Teleplanic larva – Larva capable of dispersal over long distances, such as across oceans
• Temperate – Pertaining to the latitudinal belt between 23º 27′ and 66º 33′ north or south latitude
• Tentacle – Elongated, flexible organ of some animals (eg
• Terminal anchor – In hydraulically burrowing organisms: any device used to anchor the leading portion of the burrower, permitting muscular contraction to drag the rest of the body into the sediment
• Territoriality – Defense of a specified location against intruders
• Territory – The space required, in cubic dimensions (HxWxL), by either a solitary fish, pair, or harem
• Tertiary production – The production of living material per unit area (or volume) per unit time by organisms consuming the herbivores
• TFC – Thin film composite, type of RO membrane
• TFN – Thanks for nothing
• Thallus – A plant body undifferentiated into stem, root, or leaf.
• Thermocline – Depth zone within which temperature changes maximally
• Thermohaline circulation – Movement of seawater that is controlled by density differences that are largely explained in terms of temperature and salinity
• TIA – Thanks in advance
• TIC – Tongue in cheek
• Tidal current – A water current generated by regularly varying tidal forces
• Tides – Periodic movement of water resulting from gravitational attraction between the earth, sun, and moon
• Total Hardness – A measure of the total amount of both magnesium & calcium salts dissolved in water…including carbonates
• Trace Elements – A term used to describe the many necessary elements in a marine aquarium, although usually in very small amounts
• Trade winds – Persistent winds at low latitudes in both the Northern and Southern hemispheres, blowing toward the west and the equator
• Trench – Deep and sinuous depression in the ocean floor, usually seaward of a continental margin or an arcuate group of volcanic islands
• Trickle Filter – A biological filtration system which consists of a plastic chamber with a biological filtration media
• Trophic level – In a food chain, a level containing organisms of identical feeding habits with respect to the chain (e.g., herbivores)
• Tropical – Being within the latitudinal zone bounded by the two tropics (23º 27′ north and south latitude)
• TTYL – Talk to you later
• Tubercle – Small white pustules on the gill covers which exists mainly on freshwater cyprinids
• Tudifex Worms – Small reddish
• Turbidity – The weight of particulate matter per unit volume of sea water
• Turbulence – Refers to how rapid and strong the water movement is
• TY – Thank You
• UGF – Under gravel filter
• UHMW – Ultra High Molecular Wieght plastic
• Ultraplankton – Planktonic organisms that are less than 2 micrometers in size
• ultraviolet (UV) light – Ultraviolet is a high energy, short wavelength of light
• Ultraviolet Sterilizer – A purification method which uses ultraviolet light to kill harmful bacteria and micro organisms
• Umbo / Umbones (plural) – The apparent “apex” or “beak” of each valve around which “radial” growth has proceeded.
• Undergravel Filter – (see UGF)
• Uniform spatial distribution – Situation in which individuals are more evenly spread in space than would be expected on the basis of chance alone
• Upwelling – The movement of nutrient
• UV – Ultra violet, type of light, shorter wavelength than visible light
• UV Sterilizer – A purification method which uses ultraviolet light to kill harmful bacteria and micro organisms
• UV sterilizer – A UV Sterilizer is a device that uses ultraviolet light to make the water treated with it free of microorganisms which may cause disease.
• VBG – Very Big Grin
• Ventral Fin – (see Pelvic Fins)
• Ventral Surface – The bottom area of the fish
• Vents – See Hydrothermal vents
• Venturi – A popular protein skimmer design
• Vertically homogeneous estuary – An estuary in which, at any given location, wind or tidal mixing homogenizes salinity throughout the water column
• VHO – Very high output fluorescent light
• VHO Lighting – Very High Output fluorescent lighting
• Vitamin – Chemical substances required in trace concentrations acting as a cofactor with enzymes in catalyzing biochemical reactions
• Viviparous (development) – Refers to development of an organism through the juvenile stage within a parent
• W – Watts
• Wash zone – The depth zone in which sediments are disturbed by wave action near the shoreline
• Water mass – A body of water that maintains its identity and can be characterized by such parameters as temperature and salinity
• Watershed – The land area that is drained by a river or estuary and its tributaries
• Weber’s apparatus – described in 1820 by E
• Westerlies (prevailing westerlies) – Persistent eastward
• Wet/Dry Filter – A biological filtration system which consists of a plastic chamber with a biological filtration media
• Windward [side] – The side of an island that faces a persistent wind
• Within – habitat comparison
• WMC – Western Marine Conference, United States
• Wrack zone – A bank of accumulated litter at the strandline
• WYSIWYG – What you see is what you get
• YMMV – Your mileage may vary
• YVW – You’re very welcome
• YW – You’re Welcome
• Zeolite – An ammonia removing substance
• Zonation – Occurrence of single species or groups of species in recognizable bands that might delineate a range of water depth or a range of height in the intertidal zone
• zooplankton – see plankton.
• Zooplankton – Animal members of the plankton
• Zooxanthellae – A group of dinoflagellates living endosymbiotically in association with one of a variety of invertebrate groups (e.g., corals)