Balanus perforatus
Encyclopedia
Balanus perforatus is a species of barnacle
in the family Balanidae
. It is found on the lower shore and in the neritic zone
in the warm temperate parts of the eastern Atlantic Ocean.
including the Mediterranean Sea
and the English Channel
. Its most northerly extent is in southern areas of England
and Wales
, and at this limit of its range it can be greatly affected by severe winters. It has been expanding its range with the rises in temperature that have been occurring in recent decades. It is found on rocks and man-made structures from mid-shore to the neritic zone
and also forms part of the fouling
community on the hulls of ships.
.
Breeding takes place between May and September in the English Channel when the quantity of planktonic food for the larvae is at its greatest. Initially the larvae are brooded by the adult and after their first moult are released into the water column. There are five further nauplius stages during which the larvae feed, grow, moult, drift with the currents and form part of the zooplankton
. The last stage cyprid larvae then settle out and attach themselves to a suitable substrate
.
on shady overhanging rocks and cave entrances and also bryozoa
ns and ascidians
in deeper shade.
The isopod
crustacean
Crinoniscus equitans
is an ectoparasite
of B. perforatus. Another isopod crustacean, Naesa bidentata, normally lives in rock crevices and under seaweed and stones but with the spread of B. perforatus, it has adopted the empty shells of the barnacle as its home.
Barnacle
A barnacle is a type of arthropod belonging to infraclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in erosive settings. They are sessile suspension feeders, and have...
in the family Balanidae
Balanidae
Balanidae is a family of barnacles of the order Sessilia.- Genera :* †Alessandriella Carriol, 2001* Amphibalanus Pitombo, 2004* Arossia Newman, 1982* Austromegabalanus Newman, 1979* Balanus Da Costa, 1778* †Concavus Newman, 1982...
. It is found on the lower shore and in the neritic zone
Neritic zone
The neritic zone, also called coastal waters, the coastal ocean or the sublittoral zone, is the part of the ocean extending from the low tide mark to the edge of the continental shelf, with a relatively shallow depth extending to about 200 meters...
in the warm temperate parts of the eastern Atlantic Ocean.
Description
B. perforatus is a large barnacle which grows up to 30 millimetres (1.2 in) in both diameter and height. Its shape resembles a volcano with steep sloping sides. The six fused lateral calcareous plates are pale purplish-brown and often ridged vertically. They often separate near the top leaving jagged ridges. Tissue inside the operculum is brightly coloured. Two pairs of moveable plates cover the operculum which can be sealed by a purplish-brown flap when the barnacle is exposed above water or it is not feeding.Distribution
B. perforatus is found on coastlines along the eastern side of the Atlantic OceanAtlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
including the Mediterranean Sea
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...
and the English Channel
English Channel
The English Channel , often referred to simply as the Channel, is an arm of the Atlantic Ocean that separates southern England from northern France, and joins the North Sea to the Atlantic. It is about long and varies in width from at its widest to in the Strait of Dover...
. Its most northerly extent is in southern areas of England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
and Wales
Wales
Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...
, and at this limit of its range it can be greatly affected by severe winters. It has been expanding its range with the rises in temperature that have been occurring in recent decades. It is found on rocks and man-made structures from mid-shore to the neritic zone
Neritic zone
The neritic zone, also called coastal waters, the coastal ocean or the sublittoral zone, is the part of the ocean extending from the low tide mark to the edge of the continental shelf, with a relatively shallow depth extending to about 200 meters...
and also forms part of the fouling
Fouling
Fouling refers to the accumulation of unwanted material on solid surfaces, most often in an aquatic environment. The fouling material can consist of either living organisms or a non-living substance...
community on the hulls of ships.
Biology
When submerged, B. perforatus extends its cirri and beats then rhythmically at a rate of between two and twenty-four beats per ten seconds. The cirri are less extended when the beat rate is faster. It feeds on plankton and as well as catching food particles, it pumps water through its mantle cavity. The faster the beating, the more water is pumped and the volume may reach one litre per hour. Slow beat rates are linked to pauses while the cirri are retracted rather than a reduction in the speed of movement of the cirri. B. perforatus is well adapted to life as an efficient current-producing suspension feederFilter feeder
Filter feeders are animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feeding are clams, krill, sponges, baleen whales, and many fish and some sharks. Some birds,...
.
Breeding takes place between May and September in the English Channel when the quantity of planktonic food for the larvae is at its greatest. Initially the larvae are brooded by the adult and after their first moult are released into the water column. There are five further nauplius stages during which the larvae feed, grow, moult, drift with the currents and form part of the zooplankton
Zooplankton
Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word "zooplankton" is derived from the Greek zoon , meaning "animal", and , meaning "wanderer" or "drifter"...
. The last stage cyprid larvae then settle out and attach themselves to a suitable substrate
Substrate (biology)
In biology a substrate is the surface a plant or animal lives upon and grows on. A substrate can include biotic or abiotic materials and animals. For example, encrusting algae that lives on a rock can be substrate for another animal that lives on top of the algae. See also substrate .-External...
.
Ecology
In the habitats occupied by B. perforatus it is often associated with sponges and encrusting red seaweedsCoralline algae
Coralline algae are red algae in the order Corallinales. They are characterized by a thallus that is hard because of calcareous deposits contained within the cell walls...
on shady overhanging rocks and cave entrances and also bryozoa
Bryozoa
The Bryozoa, also known as Ectoprocta or commonly as moss animals, are a phylum of aquatic invertebrate animals. Typically about long, they are filter feeders that sieve food particles out of the water using a retractable lophophore, a "crown" of tentacles lined with cilia...
ns and ascidians
Ascidiacea
Ascidiacea is a class in the Tunicata subphylum of sac-like marine invertebrate filter feeders. Ascidians are characterized by a tough outer "tunic" made of the polysaccharide tunicin, as compared to other tunicates which are less rigid.Ascidians are found all over the world, usually in shallow...
in deeper shade.
The isopod
Isopoda
Isopods are an order of peracarid crustaceans, including familiar animals such as woodlice and pill bugs. The name Isopoda derives from the Greek roots and...
crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
Crinoniscus equitans
Crinoniscidae
Crinoniscidae is a family of isopod crustaceans in the suborder Cymothoida. The original description was made by Bonnier in 1900. Members of this family are parasites, mostly on other crustaceans...
is an ectoparasite
Parasitism
Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred to organisms with lifestages that needed more than one host . These are now called macroparasites...
of B. perforatus. Another isopod crustacean, Naesa bidentata, normally lives in rock crevices and under seaweed and stones but with the spread of B. perforatus, it has adopted the empty shells of the barnacle as its home.