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Glossary of Terms

Source: Cornwall, Ira E. 1955. The Barnacles of British Columbia. Royal British Columbia Museum, Victoria.

Acorn Barnacle
A barnacle without a stalk, attached directly to its support
Adductor muscle or adductor scutorum
The main muscle for closing the operculum; it is attached to each scutum at the adductor muscle.
Adductor ridge
A ridge on the interior of the scutum between the tergal margin and the pit for the attachment of the adductor muscle.
Ala, pl. alae
The thin portion of the wall-plate which projects from the side and is overlapped by the radius and part of the adjoining plate.
Anal opening or anus
The posterior opening of the alimentary canal. It opens through the dorsal base of the penis.
Two segmented organs which protrude between the valves during the free-swimming stage. The third segment of each forms a sucker-like disk connected with the cement glands, and serves for the first attachment of the animal.
Antenna, pl. antennae
Articulated organs of sensation present during part of the free-swimming stagtes of barnacles.
Apical ridge
A ridge on the interior of the scutum (found only in species of Verruca of tropical seas).
The upper angle of the scutum and of the tergum. The upper part of the plates forming the wall.
Articular furrow
A furrow on the tergal margin of the scutum and the scutal margin of the tergum, for the articulalation of the two valves.
Articular ribs
Ribs on the interior of the scutum of Verruca below the articular furrow; variable in number and position.
Articular ridge
The ridge on the scutum and also on the tergum which helps to lock the two valves together.
Basis or base
The floor-like part of the barnacle which is attached to the rock or other support; calcareous in some species, membraneous in others.
Referring to the parts adjacent to the basis or base.
Basal margin
The margin of the scutum between the tergal margin and the occludent margin.
Branchia, pl. branchiae
Respiratory organs. One or more pair are always present in the Balanidae.
The enlarged and usually flattened part of a pedunculate barnacle in which the body is enclosed.
The compartment or plate in teh shell of Balanus with two alae. IN Chthamalus the carina and rostrum both have alae. The long posterior cirri are next to the carina. IN pedunculate barnacles it is the keel-like plate extending up between the terga.
Referring to the parts adjacent to the carina.
The narrow compartments of the shell of Balanus next to the carina. They have alae on one side and radii on the other.
Carinal latus
The plate projecting under the carina of the capitullum of Scalpellum
Carinal margin
The margin of the terga next to the carina.
Caudal appendages or caudal furca
The simple of segmented appendages seated over the anus; present, with few exceptions, in all the Lepadidea and Verrucidea.
An amorphous horny substance forming the harder part of the outer integument of Crustacea.
Cirrus, pl. cirri
The thoracic appendages or legs of the barnacle. They consist of the peduncle, or protopodite, bearing two segmented rami. The cirri form the sweep that captures the food.
The subclass of the Crustacea that includes barnacles.
The plates forming the wall of the shell.
Complemental males
Small male barnacles that assist in the fertilization of some species of barnacles.
Crests for the depressor muscles
These crests, or grooves, run from the basal margin or the tergum toward the apex.
The divisions between cells in the parietal tubes.
The last free-swimming stage of the barnacle larvae.
Depressor muscles
Muscles attached to the crests on the terga for closing the opercular plates.
The outer non-sensitive layer of the skin.
The moulting of the membraneous covering of the body.
Filamentary appendages
Tapering appendages attached to the bases of several cirri in some species; to the prosoma in others. They are believed to be respiratory organs.
A mass or concentration of nerve cells.
Mouth parts.
An individual having both male and female organs of reproduction.
Inframedian latus
The plate on the capitulum of a pedunculate barnacles set below the scutum and upper latus.
Infra-aesophageal ganglion
The ganglion located beneath the aesophagus.
The organ which acts as an upper lip. In the pedunculate barnacles it is thick and rounded. In Balanus it is not thick and has a central notch.
Spaces between tissues that serve in place of vessels for the circulation of the body fluids.
Lamina, outer and inner
The shelly wall forming the compartments of sessile barnacles. The parietal tubes, when present, are between them.
The plates in the wall of Balanus between the carino-laterals and the rostrum. in Chthamalus between carina and rostrolaterals.
The plates forming the lower rows at the base of the capitulum.
The anterior pair of mouth appendages.
The lining of the cavity in which the body lies.
Maxilla, pl. maxillae
Mouth parts set parallel with the mandibles, pointing toward the labrum.
The larvaal stage following the nauplius.
The casting-off of the membranous covering of the body and of its appendages; exuviation.
Nauplius, pl. nauplii
The first free-swimming stage of crustaceans.
Conforming to type. An ncrowded or free-growing specimen.
The gullet.
Outer maxilla or second maxilla
Those organs set close together on a prominence facing the labrum and serving as an under-lip.
Occludent margin
The margin of the opening through which the cirri are protruded.
The movable plates, scuta and terga and the membrane connecting them, that form the cover of the opening through which the cirri are protruded.
Opercular membrane
The membrane surrounding the opening through which the cirri are protruded.
Ovigerous lamellae
Delicate, transparent membranes which hold the eggs or ova in sheets; the ova lie in layers from two to four deep on each side of the sack in pedunculate barnacles.
The wall-plates of sessile barnacles.
Two club-shaped sensory organs attached to the upper margin of the labrum.
Having a comb-like edge.
The stalk or support of the capitulum. Also the support of the two rami of the cirri.
The soft rounded portion of the body. It is in the normal position of the head of an animal.
The segmented support or peduncle of the two rami of the cirri.
The part of hte wall-plate that overlaps the ala of the next plate
A branch of the cirrus; each cirrus has two rami, anterior and posterior.
Rostral latus
The lateral plate under teh basal margin of the sctum and partly under the rostrum; not present in all pedunculate barnacles.
Referring to the parts adjacent to the rostrum.
These plates have radii on both sides.
A wrinkle or fold.
The two triangular opercular plates nearest the prosoma.
The walls dividing the parietal tubes into a series of cells. Also the walls between the parietal tubes.
The parts of the shell surrounding the orifice.
Covered with spines.
Splanchnic nerves
The two larger nerves connected to the oseophageal ganglion. The ganglion located above the oesophagus.
The line or seam formed by the union of two plates. In some species the edges of the plates are toothed and interlocked, giving the whole structure great strength.
The projection on the basal margin or the tergum.
Tegral margin
The margin of the sctuum adjacent to the tegrum.
Trophi or ghathites
The mouth parts--labrum, mandibles, maxilla and outer maxila.
Upper latus
The valves, or plates, on the capitulum of a pendunculate barnacle which project between the lower margin of the tergum and the scutum.
Whale barnacle
An acorn barnacle found on certain species of whales.


Please cite these pages as:

Author, date, page title. In:   Klinkenberg, Brian. (Editor) 2023. E-Fauna BC: Electronic Atlas of the Fauna of British Columbia []. Department of Geography, University of British Columbia, Vancouver. [Date Accessed]

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