Balanus balanoides Linnaeus, 1767.
OTHER COMMON NAMES
English: Acorn shell, widespread barnacle, acorn barnacles, stalkless barnacle; French: Balane, gland-de-mer; Portuguese: Bálanos, bolotas-do-mar, caracas, glandes-do-mar.
Reaches 0.19–0.59 in (5–15 mm) in diameter. Carapace is conical, with six grey or white fused calcareous plates forming a lateral wall. The dorsal anterior plate is the biggest. The carine is posterior and two pairs of plates are placed laterally. On prime, two pairs of quick calcareous and articulated plates, the terga and scuta (one pair on both sides) type the operculum in a diamondshaped association; it encloses the mantle cavity and will be opened and closed by muscle groups. When rotated laterally, they type an aperture by means of which leads to the mantle cavity and the six pairs of birramous cirri bordered by chaetae, the primary three being shorter than different three. Tissue inside opercular aperture is normally white or pinkish. Attaches to rock utilizing the flattened and broad membranous attachment disc.
Found in intertidal rocky shores in North America, Europe, and the Arctic.
Common and considerable in rocky shores. It settles on all kinds of strong objects together with pilings, rocks, and shell crabs. Prefers low-tide areas sometimes splashed by water.
The calcareous carapace protects the animal, and the operculum hermetically seals the carapace; when the tide goes out, they shut the carapace. Survives freezing climate in the course of the winter in tide zones of the Arctic Ocean, in addition to the every day dry 6–9 hours between excessive tides throughout summer time. Eggs and nauplii within the mantle cavity additionally survive. In very dense colonies, younger don't discover sufficient house to develop, so the wall plates turn out to be elongate, resembling stalks, elevating the feeding place as in pedunculate barnacles; on rocky coasts, they type a large band that may stretch for miles. Turbulence and waves are of significance for the reason that present brings plankton for feeding. Fewer people settle in areas with out sturdy waves.
FEEDING ECOLOGY AND DIET
Feeds solely throughout excessive tide when the carapace is roofed by water. Food is small and picked up by filtering; animal opens operculum and extends the final three lengthy pairs of cirri, that are unfold and curved outward resembling a fan-shaped internet. It rhythmically extends and retracts the cirri and collects materials, transferring it to mouthparts. Cirri can do 33–37 beats per minute to gather food. Preyed on extensively by the canine whelk, Nucella lapillus, and the shanny, Lipophrys pholis.
Hermaphrodite; has an extensible penis that fertilizes neighboring people. Eggs are fertilized within the mantle cavity; gravid people every comprise 6,000–13,000 nauplii in mantle cavity. After some levels as a nauplius, a cyprid larva begins to search a spot of attachment. The antennae and cement glands make the attachment onto objects. During metamorphosis animals can develop to a diameter of 0.23–0.27 in (6–7 mm) in 58 days. Lives for 3–eight years. In some localities, all younger molt synchronously. Individuals in identical place hatch nauplii at identical time; a great variety of larvae settle in identical place, assuring cross-fertilization.
Not listed by the IUCN.