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Adductor muscle |
large muscle (or muscles) that pull the two shell valves together |
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Algae |
aquatic plants that reproduce by spores |
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Anterior |
front or head |
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Auricle |
with respect to scallops, the ear or wing-like projections at the hinge of a scallop (can also refer to the chamber of heart that receives blood from the body) |
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Axenic |
culture of a single species in bacteria-free conditions |
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Biting |
condition where shell margins of two scallops become interlocked, and subsequently damage the inner soft parts |
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Bivalve |
mollusc of the Class Pelecypoda, having a shell of two valves that are joined by a hinge |
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Byssus |
thread-like filaments used by bivalves to attach themselves to a substrate |
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Cilia |
hair-like structures whose rhythmic beat induces a water current in bivalves |
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Ctenidia |
leaf-like appendages that function in respiration and filtration of food from water (used interchangeably with the term gills) |
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Cultch |
material used to collect bivalve spat |
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Demibranch |
single plate or leaf of a bivalve gill |
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Detritus |
fragmented or decomposing organic material from plant and animal remains |
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Diatom |
a single-celled alga of the Class Bacillariophyceae; cells are enclosed in a siliceous shell called a frustule, cells can form chains |
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Dimyarian |
bivalves with two adductor muscles, e.g. clams and mussels |
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Dioecious |
organisms in which male and females reproductive organs occur in different individuals |
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Diploid |
the normal number of chromosomes (2n) in cells |
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Dorsal |
the back or part of an organism away from the ground |
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Downwelling |
in hatchery terminology, a growing system in which the flow of water enters at the top of a spat holding container (compare with upwelling) |
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D-larva |
the early veliger larval stage of bivalves, also known as straight-hinge larva |
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Embryo |
organism in early stages of development; in bivalves, prior to larval stage |
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Exhalant |
area of bivalve where water currents have an outward direction |
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Exotic |
introduced from foreign country or geographic area |
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Eyespot |
simple organ that develops near centre of mature larvae of some bivalves and is sensitive to light |
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Fertilization |
union of egg and sperm |
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Flagellate |
group of single-celled algae characterized by having a locomotory organ called a flagellum |
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Frustule |
siliceous shell-like covering of a diatom |
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Gamete |
mature, haploid, functional sex cell capable of uniting with the alternate sex cell to form a zygote |
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Gametogenesis |
process by which eggs and sperm are produced |
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Gill |
a leaf-like appendage that functions in respiration and filtration of food from water (see ctendia) |
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Growout |
the process of growing seed produced in hatcheries to market size |
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Halocline |
a zone of sharp vertical salinity change |
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Hinge |
dorsal area of bivalve shell where two valves are joined together |
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HUFA |
a highly unsaturated fatty acid, referred to also as polyunsaturated fatty acid (PUFA) |
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Indigenous |
native, not imported |
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Inhalant |
area of bivalve where water current have an inward direction |
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Larva |
a stage of bivalves from the embryo to metamorphosis |
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Ligament |
fibrous spring-like material joining two valves of a bivalve at the hinge |
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Mantle |
the soft fold enclosing the body of a bivalve which secretes the shell |
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Mean |
average |
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Meiotic Division |
process in which normal number of chromosomes (2n) is reduced to the haploid (n) number |
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Metamorphosis |
in bivalves, the period of transformation from the larval to the juvenile stage |
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Microalgae |
small cell-size algae, either single celled or chain forming diatoms, cultured as foods for larvae and spat in a hatchery |
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Microlitre (µl) |
one millionth of a litre or one thousandth of a ml |
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Micrometer (µm) |
one millionth of a metre or one thousandth of a mm |
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Monoecious |
organisms in which both male and female reproductive organs occur in the same individual |
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Monomyarian |
bivalves with one adductor muscle, e.g. oysters and scallops |
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Natural Set |
in bivalves, obtaining spat from spawning of natural populations |
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Pallial Line |
faint circular line on inner surface of shell of bivalves showing location of attachment of mantle to shell |
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Palp |
a sensory appendage near the mouth used to assist in moving food into the mouth |
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Pedal |
pertaining to the foot |
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pH |
a measure of acidity |
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Plankton |
floating or weakly swimming aquatic organisms, can be phytoplankton (plants) or zooplankton (animals) |
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Planktotrophic |
organisms that feed on phytoplankton |
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Polar Body |
minute cells released during meiotic division of the egg after the sperm has penetrated the egg; contains excess chromosomal material to produce a haploid egg |
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Polyploid |
animals having more than the usual number of diploid (2n) chromosomes |
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Posterior |
the rear, away from the head |
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Pronuclei |
in the egg, the haploid nucleus after completion of meiosis but before infusion with the sperm nucleus |
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Pseudofaeces |
false faeces, waste material not taken into the digestive tract |
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PSU |
a measure of salinity, equivalent to parts per thousand |
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Resilium |
internal portion of the ligament located centrally along the hinge of a bivalve; causes the valves to open when the adductor relaxes |
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Salinity |
the salt content of seawater usually measured in parts per thousand (ppt) or practical salinity units (PSU) |
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Seed |
a hatchery term for spat of a size ready for sale |
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Settlement |
behaviourial process when mature bivalve larvae seek a suitable substrate for attachment |
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Shell Height |
the straight line distance measured perpendicularly from the umbo to the ventral margin of the shell |
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Shell Length |
the straight line distance from the anterior to the posterior margins of the shell |
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Spat |
a newly settled or attached bivalve (also termed post larval or juvenile in bivalves) |
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Straight-hinge larva |
early part of larval stage, sometimes termed D-stage |
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Tentacle |
long, unsegmented threadlike protuberance from edge of mantle that has specialized sensory function |
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Tetraploid |
polyploid animal with twice the normal complement of chromosomes (4n) |
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Thermocline |
a zone of sharp vertical temperature change |
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Triploid |
a polyploid animal with an extra set of chromosomes (3n) |
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Trochophore |
planktonic stage of bivalve embryo |
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Umbo |
beak-like projections at the dorsal part of the shell; it is the oldest part of a bivalve shell (also called the umbone) |
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Upwelling |
in hatchery terminology, a growing system in which a flow of water is induced through the base of a spat holding container (compare with downwelling). |
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Urogenital System |
system with organs concerned with excretion (kidney) and reproduction (gonad) |
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Valve |
one of the two parts of a bivalve shell, two valves make up one shell |
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Veliger Larva |
the larval stage of most molluscs, characterized by the presence of a velum |
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Velum |
ciliated locomotory organ of the larva |
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Ventral |
pertaining to the under or lower side of an animal |
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Zygote |
diploid (2n) cell resulting from union of male and female gametes |
