MarLIN Glossary

Glossary items


Containing calcium carbonate; chalky. Of organisms - a species which accumulates calcium carbonate in its tissues.


Club-shaped sensory projections on antennules and antennae, in some gammaridean amphipods; not found outside Gammaridea


Plural of 'callosity'.


A distinct, often bulbous, roughened area of skin (OED, 2008).


Enlarged or swollen at the apex, with a 'head', clubbed. (Prescott , 1969).


The bulbous main hard body of organisms such as goose barnacles (OED, 2005).

cardinal teeth

Of bivalve mollusc shells - projections about the middle of the shell hinge, but not always, diverging from the beaks (Tebble, 1976).


Crustacean shell feature, typically a ridge on the surface of the exoskeleton. In barnacles the carina is the posterior compartmental plate.


A predator which feeds on animals


An early life-cycle phase of marine algae (Lincoln et al., 1998).


In crustacea, the limb segment basal to the propodus. Basic crustacean limb comprised of Coxa-basis-ischium-merus-carpus-propodus-dactylus.


A small fleshy outgrowth or appendage (OED, 1990).


Of fish - downward-running: spending most of their life in rivers and migrating downstream to the sea in order to breed (e.g. eels) (cf. 'anadromous').


'Catworm' or 'Cat worm' is the common name for polychaete worms belonging to the Family Nephtyidae, e.g. Nephtys hombergii.


Refering to the tail (OED, 2008).

caudal keel

A ridge either side of the caudal fin base. It is used for stability in some shark species (Lincoln et al., 1998)

caudal keels

Plural of 'caudal keel'.

caudal peduncle

The base of the caudal fin (OED, 2008).


A hollow normally eroded in a cliff, with the penetration being greater than the width at the entrance (based on Sunamura, 1992). Caves can also be formed by boulders. Not defined for the EC Habitats Directive, 'Submerged or partially submerged sea caves' (European Commission, 1995) but the UK interpretation considers them to take the form of tunnels or caverns, with one or more entrances, in which vertical and overhanging rock surfaces form the principal marine habitat.

Celtic Sea

Seas to the south of Ireland and west of Cornwall (south-west England).

centrodorsal ossicle

Of Crinoidea (crinoids); the largest of the ossicles of the calyx of a feather-star, to which the cirri are joined (adapted from Southward & Campbell, 2006).


Singular of 'cerata'.


Dorsal processes in some shell-less opistobranch molluscs, containing branches of the digestive tract. The cerata are often brightly coloured and bear defensive organs, either glandular in nature, or formed of batteries of stinging cells derived from their cnidarian prey e.g. hydroids, soft corals and sea anemones (based on Thompson & Brown, 1976 and Picton & Morrow, 1994).


(or setae) Chitinous bristles found in oligochaete annelids and especially in polychaete annelids.


A soft fine-grained sedimentary rock, normally white, consisting almost entirely of calcium carbonate.


1) Of characters - a distinguishing feature, the distinctive state or expression of a character (based on Lincoln et al., 1998). 2) Of species - special to or especially abundant in a particular situation or biotope. Characteristic species should be immediately conspicuous and easily identified (based on Hiscock & Connor, 1991).

chart datum

Set reference point on charts for water depth in relation to tides. On metric charts for which the UK Hydrographic Office is the charting authority, chart datum is a level as close as possible to Lowest Astronomical Tide (LAT), the lowest predictable tide under average meteorological conditions (from Ministry of Defence, 1987). This is not the same as Ordnance Datum, the fixed reference point for heights and contours shown on Ordnance Survey maps, which is based on mean sea level (MSL) as recorded at Newlyn (Cornwall) over a seven-year period from 1915 to 1921.


Appendage where the terminal segment (dactyl) forms a movable finger that moves against an immovable finger on the subterminal segment (propodus) (Ruppert & Barnes, 1996). [View image]


Plural of 'chela'.


In Pycnogonida, the first and anteriormost appendage, conisisting of one or two segments and the chela (Stachowitsch, 1992).


Plural of 'chelifore'.


The claw-bearing appendages of decapod crustaceans (see 'chela').


An organism that derives energy from endogenous light independent chemical reactions (Lincoln et al., 1998).

chlorinated hydrocarbon

A synthetic organic compound containing chlorine, highly toxic and the base for many pesticides. Includes PCBs (polychlorinated biphenyls).


Organelles present in seaweeds and plants containing chlorophyll and involved in photosynthesis (OED, 2008)


The pit or protection (of the shell hinge) to which the internal ligament is attached (Tebble, 1976).


One of numerous small pores on the column of anemones, occasionally on papillae and arranged in rows, through which acontia may be discharged (Stachowitsch, 1992).


Plural of 'cinclide'.


The subzone of the rocky sublittoral below that dominated by algae (the infralittoral), and dominated by animals. No lower limit is defined, but species composition changes below about 40m to 80m depth, depending on depth of the seasonal thermocline. This subzone can be subdivided into the upper circalittoral where foliose algae are present and the lower circalittoral where they are not (see Hiscock, 1985). The term is also used by Glémarec (1973) to refer to two étages of the sediment benthos below the infralittoral: a "coastal circalittoral category with a eurythermal environment of weak seasonal amplitude (less than 10°C) varying slowly" and a "circalittoral category of the open sea with a stenothermal environment". 1) lower The part of the circalittoral subzone on hard substrata below the maximum depth limit of foliose algae (based on Hiscock, 1985).
2) upper The part of the circalittoral subzone on hard substrata distinguished by the presence of scattered foliose algae amongst the dominating animals; its lower limit is the maximum limit of depth for foliose algae (based on Hiscock, 1985).


Slender hair-like filaments opften used during feeding (OED, 2005)


1) taxonomy - the placing of animals and plants in a series of increasingly specialized groups because of similarities in structure, origins etc., that indicate a common relationship (from Makin, 1991). 2) biotopes - the process of identifying distinctive and recurrent groupings of species with their associated habitat and describing them within a structured framework.


Latticed (Holmes, 1979).


1) Sediment particles less than 0.004 mm in size (Wentworth, 1922). 2) A soft very fine-grained sedimentary rock composed primarily of clay-sized particles.


Any slope, usually of bedrock but can be clay, steeper than 45°.


The totality of the weather conditions at a certain location over a certain period (conventionally 30 years) (from Baretta-Bekker et al., 1992).


An assemblage of organisms derived by asexual or vegetative multiplication from a single original parent - generally assumed to be genetically identical (from Lincoln et al., 1998).

coastal cell

A compartment of coastline, divided from neighbouring sections of coast in terms of longshore drift, current flow, and wave convergence and divergence (based on Motyka & Brampton, 1993).

coastal processes cell

See 'coastal cell'.

coastal zone

The space in which terrestrial environments influence marine (or lacustrine) environments and vice versa. The coastal zone is of variable width and may also change in time. Delimitation of zonal boundaries is not normally possible; more often such limits are marked by an environmental gradient or transition. At any one locality the coastal zone may be characterized according to physical, biological or cultural criteria, which need not, and rarely do, coincide (based on Carter, 1988).


A rock particle defined in two categories based on Wentworth (1922): large (128-256 mm); small (64-128 mm) (from Hiscock, 1990).


Common tissue mass connecting individual polyps, consisting mainly of mesoglea, and forming the main supporting structure of an anthozoan colony (Manuel, 1988).


The tube of living tissue of a hydroid, situated within the outer skeleton or perisarc (see perisarc) (Cornelius, 1995).


Descriptive of organisms produced asexually which remain associated with each other; in many animals, retaining tissue contact with other polyps or zooids as a result of incomplete budding (Barnes et al., 1993).


The process of establishing populations of one or more species in an area or environment where the species involved were not present before (from Baretta-Bekker et al., 1992).


1) A group of organisms of the same species living connected together in a common mass (Fitter & Manuel, 1986.) (cf. 'aggregation'). 2) A group of organisms connected by behavioural or sociological factors (e.g. seabird colony, seal colony).


Symbiosis (q.v.) in which one species derives benefit from a common food supply, whilst the other species is not adversely affected (Lincoln et al., 1998).


A group of organisms occurring in a particular environment, presumably interacting with each other and with the environment, and identifiable by means of ecological survey from other groups (from Mills, 1969; see Hiscock & Connor, 1991 for discussion) .


Curving inwards (OED, 2005).


A feeling of reliance or certainty (Thompson, 1995).


Belonging to the same genus, a congener (Lincoln et al., 1998).


Cone shaped e.g. limpet -shaped, patelliform (adapted from Stachowitsch, 1992).


"The regulation of human use of the global ecosystem to sustain its diversity of content indefinitely" (Nature Conservancy Council, 1984).


Belonging to the same species (Lincoln et al., 1998).


1) The frequency of occurrence of a species in samples from the same community (based on Makins, 1991). 2) The continued presence of a species or community at a particular location. (Cf. 'persistence', 'resilience', 'stability').


"An increase of background concentration of a chemical or radionuclide" (from Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection - GESAMP, 1995).

continental shelf

The seabed adjacent to a continent to depths of around 200 metres, or where the continental slope drops steeply to the ocean floor. Defined in law as "the sea bed and subsoil of the submarine areas adjacent to the a depth of 200 metres"; the legal landward limit is set at the outer limit of territorial waters (q.v.) (Geneva Conference on the Law of the Sea, Convention on the Continental Shelf, 1958).


Intricately folded, coiled or twisted (OED, 2008).


Relating to, or resembling, coral, especially any calcareous red alga impregnated with calcium carbonate.


Relating to the outer layer of an organism or organ (Abercrombie et al., 1973).


Of worldwide distribution (Brusca, 1980).


See 'pocket beach'.


In amphipod crustaceans a coxa is a hard ventral extension to thoracic segments, usually seven are found (Hayward & Ryland, 1995).


Plural of 'coxa'


Having a round-toothed or scalloped edge (OED, 2005).


Having a finely scalloped or notched outline or edge (OED, 2005).


Adjective of 'crenulate'


A narrow crack in a hard substratum <10 mm wide at its entrance, with the penetration being greater than the width at the entrance. Crevices often support a distinct community of species. Cf. 'fissure'.

critically endangered

IUCN Red List categories - a taxon is Critically endangered when it is facing an extremely high risk of extinction in the wild in the immediate future (International Union for the Conservation of Nature and Natural Resources 1994) (cf. 'Extinct', 'Endangered', 'Vulnerable').


Forming or resembling a crust (Thompson, 1995).


1) An animal which lives in hidden places, such as crevices, caves or beneath stones. 2) An organism whose appearance or colouration makes it difficult to see or recognise.


See 'cryptic'.


See 'cultch'.


A mass of broken stones, shells and gravel which forms the basis of an oyster bed (from Makins, 1991).


The Cumacea are a distinctive group of crustaceans with an inflated carapace, giving them the appearance of tadpoles (adapted from Hayward et al., 1996).


Belonging to the Order Cumacea.


Horizontal movement of water in response to meteorological, oceanographical and topographical factors (see also 'tidal stream') (from Ministry of Defence, 1987); a steady flow in a particular direction. 'Current' refers to residual flow after any tidal element (i.e. tidal streams) has been removed.


Prokaryotic like bacteria, lacking a cell nucleus, golgi apparatus, endoplasmic reticulum or mitochondria, but with the ability to photosynthesize. Also termed Cyanophyta.


see Cyanobacteria.


With straight sides and a circular section (Thompson, 1995).


A gonimocarp (collection of filaments of diploid cells that produce carpospores) enclosed within an envelope of tissue (pericarp) (Hoek van den et al., 1995).