Balanus

Definition and stakes

Portrait of Hugh Miller Hugh Miller,  The Foot-prints of the Creator (1850)

“ The immature Lepas is furnished with members well adapted for swimming, and with which it swims freely; as it rises towards maturity, these become blighted and weak; and, when fully grown,—fixed by its fleshy pedicle to the rock or floating log to which it attached itself in its transition state,—it is no longer able to swim. The immature Balanus is furnished with two eyes: in its state of maturity these are extinguished, and it passes its period of full development in darkness. ”
Source: Gutenberg

Portrait of Charles Darwin Charles Darwin,  A Monograph on the Sub-class Cirripedia…

“ Balanus balanoides and Chthamalus stellatus, I have observed that, when left uncovered by water, they kept the orifice of their operculums a little open, with a bubble of air within their sacks, so that the orifice was in fact closed by a thin septum of water, with air beneath; when disturbed, they closed their operculums with force, and expelled the bubble of air with a clicking noise, which has been noticed by Dr. Coldstream, [27] and has been thought to be made by the movement of the operculum itself. Bal. crenatus, a deep-water species, when out of water, keeps its operculum closed. ”
Source: Gutenberg

George Brettingham Sowerby II,  A Conchological Manual (1842)

“ The operculum always consists of more than one piece, generally of two pairs: they are either articulated to each other by serrated edges, and placed against each other conically, as in Balanus, or they lie flat in two pairs against each other. Through the ventral pair the cirrhi protrude.
The parietal valves, composing the principal part of the shell, vary in number, form and position. The anterior valves are placed on the same side with the cirrhi; the posterior, those on the opposite side; and those which remain between on each side are the lateral valves.
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Source: Wikisource

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