Prolonged dormancy – usually to avoid drying or cold.
Used for taxa or populations that occur in separate and non-overlapping geographic areas.
Pertaining to the front end of the animal.
At the apex.
Changed from the primitive state.
Relating to the base.
The community on the floor of a lake, river or stream (or on the ocean floor).
Concave above and below.
A structure divided into two projections.
Branching into two projections.
A cut-off lake formed by a meandering river (also called oxbow lakes).
With two lobes.
Divided into two branches.
Water with a salinity in between fresh water and seawater.
Relating to the gills.
One or more attachment threads produced by the byssal gland in the foot of many autobranch bivalves
Pouch-like projection from a chamber, such as the stomach.
Primarily consisting of the mineral calcium carbonate (CaCO3).
Forming a channel.
A prominent spiral ridge.
With one or more carinae.
The middle tooth of each row of teeth of the radula. Sometimes called the rhacidian tooth.
An inverted V-shape.
A polymer similar in structure to glucose. Combined with protein it forms the exoskeleton in many invertebrates.
Thin processes that extend from epithelial cells - usually motile but some are stationary.
A process of establishing, defining and ranking taxa within hierarchical series of groups.
Embryos or adults that share an identical common ancestry (i.e., not produced by sexual reproduction).
Lines with a common centre.
In the shape of a cone.
Tissue that connects, binds or supports organs and other tissues (usually rather amorphous).
Twisted or coiled.
A section or part of the body used to facilitate internal fertilisation by transferring sperm.
Distinct but fine ribbing.
Hidden or camouflaged.
A hyaline rod of mucoprotein found in the style sac of some gastropods and many bivalves.
A small projection.
Toothed, or with short ridges.
With two ducts.
Having separate sexes (male and female).
When an embryo develops through to hatching as a juvenile without going through a free-living larval stage.
Not joining or meeting. Often applied to distributions.
Away from the middle of the body or point of attachment.
Blind process or pocket.
The surface of an animal furthest away from the ground or other support, in other words upper surface.
On the upper sides of the animal.
On the lower sides of the animal.
Study of the relationship among organisms and that to their physical surroundings.
Process in which the relative movement of proteins is examined in an electric field.
Oval or egg-shaped.
Of a long shape.
Found only in a particular geographical area.
The union of a male and female gamete to form a zygote occurring outside the body of an animal typically in the water column.
No longer in existence, no longer living.
Waste material excreted from the gut of an animal.
The entire animal life of a given region, habitat, or geological stratum.
The union of a male and a female gamete to form a zygote, sometimes referred generally to the act of insemination, impregnation or pollination.
Split or cracked.
A whip-like structure on a cell. For single cells such as spermatozoa, it is the motile structure.
An organism, fragment, impression or trace of an organism preserved in a rock.
Water with a salinity of less than 0.5 parts per thousand, or alternatively, less than 2 parts per thousand (seawater is commonly around 35 parts per thousand).
Tapering at both ends; spindle-shaped.
A chitinous shield-like structure in the stomach.
A specialised respiratory surface. In molluscs, this is typically the ctenidium, however it may also be a secondary structure.
A duct transporting eggs or sperm.
Covered in granule-like pustules.
Where both male and female reproductive organs are present in the same individual. Consecutive hermaphroditism is where the male and female organs do not occur in the individual at the same time, but successively. Simultaneous hermaphroditism occurs when the male and female reproductive organs occur in the individual at the same time.
A larval stage is present in development.
The union of a male and female to transfer sperm enabling the gametes to form a zygote inside the body of an animal.
The part of the shore covered by high tide and uncovered at low tide.
Folded inwards like the finger of a glove.
Animal without a backbone or spinal column.
Showing a variety of colours when viewed from different angles.
The chitinous structure in the oral tube or outer part of the buccal cavity of gastropods – commonly primitively paired, but single (dorsal) in some.
An organism not yet fully developed, with features of both the larval stage and the adult stage.
Topography formed when rocks (typically limestone) are dissolved. Commonly rugged in shape.
Two pairs of flap-like structures on either side of the mouth in bivalves.
Raised thin ridges.
A developmental form of an organism, without adult characteristics and unable to reproduce.
From or on the side.
Still waters (as in lakes).
Spiral ridges or cords.
Flowing waters (as in streams or rivers).
Large aquatic plants (cf. algae).
Middle, or towards the middle.
The middle cusp or denticle on a radular tooth – equivalent to the main, median or central cusp.
Fine sculpture, often not visible in detail using an ordinary light microscope.
The form and structure of an organism, with special emphasis on the external features.
The slimy substance secreted by goblet cells onto the surface of a mucus membrane to protect, lubricate and trap bacteria, dust, etc.
The ring of ganglia and their connectives surrounding the buccal area or the oesophagus.
Pegs on the inner side of the operculum that provide additional surface for muscle attachment.
Pertaining to the mouth.
Pertaining to or derived from living organisms, or to compounds containing carbon as an essential component.
A normal coil.
An oval shape.
A structure that transports eggs from the gonad to the exterior. In gastropods with internal fertilisation, the eggs are fertilised in the duct and surrounded by nutrients and a covering secreted from associated albumen and capsule glands before being released.
Eggs are laid which develop outside the body of the parent.
Of an oval shape.
A gonad that produces both sperm and eggs.
Short finger-like structures (plural 'papillae').
The development of an organism from an unfertilised egg.
A female that can produce eggs that develop as embryos without the involvement of a male.
Relating to the foot.
A thin-walled chamber containing the heart.
The part of an animal that is towards the rear (i.e. that which follows when the animal is moving).
An organism that feeds by preying on other organisms, killing them for food.
A gland in the male genital tract.
Hermaphrodite that first develops as male and then becomes female.
Shaped like Pupa, a small, bullet-shaped land snail.
Small raised, rounded spots.
Covered with pustules.
Approximately square or rectangular.
An anatomical structure that is used by molluscs for feeding, sometimes compared to a tongue. It is a minutely toothed, chitinous ribbon, typically used for scraping or cutting food. Absent in bivalves and a few gastropods.
A gland-like structure in the kidney.
Of net-like appearance.
A muscle that, when it contracts, withdraws a structure.
An alternative name for the central radular teeth.
Main axis of shaft.
Rhombus-shaped (i.e., a flat shape with four equal straight sides, for example diamond-shaped).
Of rough texture.
The structure forming the tip of the everted preputium, through which the penis passes in copulation.
An undulating edge or fluted edge.
Particulate matter that has been transported by wind, water or ice and subsequently deposited, or that has been precipitated from water.
The division of a body or appendage into a linear sequence of similar units.
Stiff, minute hair-like structures.
When males and females differ in shape and/or size.
The hard outer covering of a wide variety of invertebrates and notably molluscs. Mollusc shells are mineralised with calcium carbonate (CaCO3).
A (typically large) hole in the ground (commonly in limestone).
Winding, with few to many bends.
Spatula or spoon-like.
A sac containing sperm in the female system.
A packet containing sperm that is passed from male to female in some molluscs.
Almost gone, or almost absent.
Near the umbone.
Above the anus.
Above the foot.
See filter feeder.
A radular configuration of seven teeth in each row.
The theory and practice of describing, naming and classifying organisms (also referred to as systematics).
With three cusps.
Shortened or cut off.
A single arm-like structure.
The terminal part of the female reproductive system in euthyneruans.
Describing the surface of an animal that is nearest or next to the ground or other support.
A swelling or pocket.
An expanded pouch.
Producing live offspring from within the body of the parent.
Microscopic green ‘algal’ cells that form symbiotic relationships with some molluscs (e.g. giant clams) and corals.