Distinguishing Characteristics |
Shell conical, made of 6 triangular plates (parietes) fused together with walls (radii) between plates; walls (radii) narrow at top, disappear at base with plates (parietes) touching or nearly so; plates are whitish, smooth; no horizontal striations; base plate is calcareous, usually stays on hard substrate when barnacle is removed; base plate with radial patterns; aperture diamond-shaped; opercular plates at the aperture with radial grooves; internal plate tergum with long spur (rounded extension), less than 1/4 the width of the basal margin. |
Similar Species |
May be confused with B. subalbidus. The walls (radii) of B. subalbidus are usually more narrow, sometimes almost nonexistent, at least in the conical specimens. B. improvisus has a radially grooved base. The best way to distinguish these two is by looking at the terga. B. improvisus has a long spur, and B. subalbidus has a short, wide spur. Though sometimes found together, B. improvisus prefers less saline waters than B. subalbidus. |
Habitat |
Bay, in lower salinities |
Maximum Size |
2 cm (3/4 in), usually less than 1 cm |
Other Common Names |
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Previous Scientific Names |
Amphibalanus improvisus |
Comments |