Terminology Description
Terminology Description
Aeolid A nudibranch belonging to the major group (suborder) Aeolidina.
Annulate A shape that consists of rings or ring
Anterior Toward the front of the body.
Aperture The single large terminal orifice of a shell through which the head foot is extruded.
Apertural sinus Recurved notch in margin of aperture of a shell.
Apex Narrow first formed part of shell, typically bearing a protoconch (the tip of the spire).
Apical Relating to the tip or apex.
Autotomy A defensive behaviour in which an animal deliberately casts off part of its body (usually the mantle or cerata).
Axial Describes direction of shell sculpture that is more or less parallel to the coiling axis.
Benthic Refers to an organism living on or in the substrate.
Bifid Divided by a deep cleft into two parts.
Bipinnate With small side branches arising on two sides of the main stem or axis (refers to the gill).
Bivalves An exclusively aquatic class of molluscs that has two shells that are typically symmetrical along the hinge line and feed by siphoning and filtering particles from the water.
Body whorl One complete spiral turn of a univalve shell.
Branchial pocket A cavity in the posterior midline of a dorid’s body into which the gills can be retracted.
Buccal Referring to the mouth or mouth cavity.
Carnivorous Literally a meat
Caryophyllidia Specialised spiculose tubercles on the mantle surface of some cryptobranchdorids.
Cerata (singular ceras) Finger
Caruncle Elevated ridge or lobe with presumed sensory function.
Caudal Relating to the tail.
Chloroplasts The plastid within a plant cell that contains chlorophyll and is the site of photosynthesis.
Cilia Fine hair
Clavus The distal portion of the rhinophore above the stalk. It is often expanded and ornamented with lamellae or papillae.
Club See clavus.
Cnidosac A small cavity at the apex of each ceras of aeolids in which unexploded nematocysts aquired from the cnidarian food are stored.
Columella The pillar forming the central axis of the shell around which the whorls spiral of a shell.
Columellar lip Inner lip of aperture of a shell.
Crenulate Finely notched; regularly indented.
Cryptic Body camouflaged to resemble part of the microhabitat; or possessing secretive behaviour.
Cryptobranch gill Gills of doridnudibranchs which can be retracted completely into a branchial pocket below the notum.
Distal That section of an organ or appendage which is most remote from the point of attachment to the body.
Digestive diverticulum A branch of the digestive gland within a ceras.
Dorid Nudibranchs with a circle of gills surrounding the anus in the midline towards the rear of the body, belonging to the major group (suborder) Doridina.
Dorsal The top surface of the animal.
Dorsum (= notum) The exposed back or top surface of a nudibranch mantle.
Endemic A species that is restricted to one or few localities in its distribution.
Epiphytic Referring to organisms living on the surface of a plant.
Filament A slender thread
Foot The large muscle mass on which gastropods move.
Fusiform Spindle shaped.
Gill (= branchia) The respiratory organ. Either in the form of single leaflets (hence pinnate) or with side branches (bipinnate or tripinnate).
Gizzard A modified region of the gut used for masticating food.
Habitat The natural environment in which an organism lives.
Herbivorous Feeding on plant material (e.g. Seaweed, encrusting microalgae).
Hermaphrodite Bisexual; an individual possessing functional male and female reproductive organs and capable of producing both sperm and eggs.
Hyponotum The under surface of the mantle.
In situ Refers to the natural environment of an animal.
Incised A deep etching or mark on the shell surface.
Infaunal Living within the substrate.
Infrapallial lobe Posterior fold of body enclosing shell of cephalaspideans.
Inner lip Inner margin of aperture overlying columellar of a shell.
Intertidal The area of foreshore that lies between high tide (when it is covered by water) and low tide (when it is exposed to the air).
Intraspecific variation Refers to natural variation in one or more charcters between individuals of the same species.
Involute Refers to the spire of the shell of the family Bullidae, which is sunk below the level of the apex.
Jaws Thickened, horny plates within the buccal cavity.
Lamellate (= perfoliate) Rhinophores bearing plates on the posterior face of the stalk or clavus.
Lappets Muscular plates or extensions associated with the mouth.
Last whorl The last most recently formed whorl of gastropod shell.
Lateral Relating to the side.
Larvae (singular: lava) The juvenile stage of an animal prior to its undergoing metamorphosis into an adult. Its form can be completely different to the adult.
Lecithotrophic Relates to the type of development in which larvae utilise only the reserves of yolk in the egg to nourish themselves.
Mantle The organ secreting the shell of molluscs. It develops into the layer that covers the body in opisthobranchs without a shell.
Margin The outer edge of the mantle.
Medial Towards the middle or midline.
Metamorphosis A biological process whereby an animal develops by undergoing a physical and abrupt change in form often accompanied by a change in habitat and behaviour.
Metapodium – Posterior extension of the mantle.
Nekton Permanently floating at the surface of the ocean.
Nematocyst The stinging organ of the Cnidaria (a microscopic capsule with a coiled thread that rapidly unwinds on discharge). Present in hydroids, sea anemones, corals, etc. Aeolidnudibranchs separate the nematocysts from the remainder of the hydroid tissues and pass them, unexpoded, through the digestive diverticulum in the cerata to the cnidosac at the tip where they are used for the aeolid’s own defense.
Nocturnal Active at night.
Notum (= dorsum) The exposed back or top surface of a nudibranch mantle.
Nudibranch Technically a member of the order Nudibranchia of the subclass Opisthobranchia (sea slugs). Equivalent of Opisthobranch in much popular literature.
Operculum A horny or calciferous plate that partially or completely closes the aperture
On retraction into the shell.
Opisthobranch Technically a member of the subclass Gastropoda (includes bubble snails, sea hares, sea butterflies, caddis slugs, sap
Oral tentacle Tentacle (or flap) around the mouth; used for food location and recognition.
Oral veil A membranous extension of the head above the mouth.
Outer lip Outer edge of aperture of a shell.
Palmate Having a shape in the likeness of a hand with the fingers extended.
Papilla (plural papillae) A small, delicate, finger
Parapodia Flap
Pelagic Passively drifting or floating at the sea surface; drifting with currents or winds.
Pericardium Sac
Periostracum The horny outermost layer of gastropod and bivalve shells.
Phanerobranch gill Gills of doridnudibranchs that cannot be withdrawn into a branchial pocket beneath the notum. They can only be contracted into a tight group above the notum.
Pinnate Bearing side branches; branched as to resemble a feather.
Planktotrophic Relates to the type of development in which larvae actively feed on micro
Plicate Folded.
Posterior Towards the rear of the body.
Propodial Located at the anterior part of the foot.
Protoconch Larval shell of a gastropod. Smallest spiral tip of a shell.
Pustule (= tubercle) A low, conical, rounded or uneven swelling on the notum.
Radula A flexible, cuticularised feeding organ contained within the buccal cavity; bears numerous minute teeth.
Respiration Exchange of gases between the environment and the organism.
Reticulum Network; any reticulated system or structure.
Rhinophore Sensory tentacle on the head, or anterior section of the mantle, of opisthobranchs.
Rhinophoral pocket The cavity into which the rhinophore of a doridnudibranch can be withdrawn.
Rhinophoral sheath Upstanding flange from the antero
Sculpture Surface structure and ornamentation on shell surface.
Siphon Elongation of mantle edge to form a tube for water flow.
Shell The molluscan shell is a calcareous exoskeleton which encloses, supports and protects the soft parts of the animal. It is formed, repaired and maintained by the mantle. In opisthobranchs it may be reduced, internal or completely lost in the adult.
Spawn Mass of eggs embedded in transparent jelly.
Spicule A minute rod or star
Spire The visible part of all the whorls except the last (shell body) whorl.
Striate Marked with fine grooves.
Subapical Section below the apex or tip.
Substrate The type of sea floor on which a benthic organism lives and grows.
Symbiosis Describes a close and often long term interaction between different species usually where both organisms benefit.
Tentacle Projecting sensory appendage associated with the head or mouth.
Tripinnate With small side branches arising from three sides of the main stem or axis (refers to the gill).
Truncate shortened abruptly, squared off.
Uniseriate In relation to the arrangement of teeth in the radula where there is a single tooth in each row.
Ventral The underside of the animal.
Viscera The soft interior organs of the body.
Whorl One complete spiral turn of a univalve shell.
Zooxanthellae Symbiotic dinoflagellates in many