THE BARNACLES OF BRITISH COLUMBIA

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.

Antennules

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).

Apex

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.

Basal

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.

Capitulum

The enlarged and usually flattened part of a pedunculate barnacle in which the body is enclosed.

Carina

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.

Carinal

Referring to the parts adjacent to the carina.

Carinolaterals

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.

Chitin

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.

Cirripedia

The subclass of the Crustacea that includes barnacles.

Compartments

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.

Cross-septa

The divisions between cells in the parietal tubes.

Cypris

The last free-swimming stage of the barnacle larvae.

Depressor muscles

Muscles attached to the crests on the terga for closing the opercular plates.

Epidermis

The outer non-sensitive layer of the skin.

Exaviation

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.

Ganglion

A mass or concentration of nerve cells.

Gnathites

Mouth parts.

Hermaphrodite

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.

Labrum

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.

Lacunae

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.

Laterals

The plates in the wall of Balanus between the carino-laterals and the rostrum. in Chthamalus between carina and rostrolaterals.

Latera

The plates forming the lower rows at the base of the capitulum.

Mandibles

The anterior pair of mouth appendages.

Mantle

The lining of the cavity in which the body lies.

Maxilla, pl. maxillae

Mouth parts set parallel with the mandibles, pointing toward the labrum.

Metanauplius

The larvaal stage following the nauplius.

Moulting

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.

Normal

Conforming to type. An ncrowded or free-growing specimen.

Oesophagus

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.

Operculum

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.

Paries

The wall-plates of sessile barnacles.

Palpus

Two club-shaped sensory organs attached to the upper margin of the labrum.

Pectinated

Having a comb-like edge.

Peduncle

The stalk or support of the capitulum. Also the support of the two rami of the cirri.

Prosoma

The soft rounded portion of the body. It is in the normal position of the head of an animal.

Protopodite

The segmented support or peduncle of the two rami of the cirri.

Radius

The part of hte wall-plate that overlaps the ala of the next plate

Ramus

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.

Rostral

Referring to the parts adjacent to the rostrum.

Rostrolaterals

These plates have radii on both sides.

Ruga

A wrinkle or fold.

Scutum

The two triangular opercular plates nearest the prosoma.

Septum

The walls dividing the parietal tubes into a series of cells. Also the walls between the parietal tubes.

Sheath

The parts of the shell surrounding the orifice.

Spinose

Covered with spines.

Splanchnic nerves

The two larger nerves connected to the oseophageal ganglion. The ganglion located above the oesophagus.

Suture

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.

Spur

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.