Pollicipes pollicipes
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The barnacle (Pollicipes pollicipes) is a barnacle crustacean of the Pollicipedidae family that grows on rocks beaten by waves. It feeds by filtering, since, due to its lack of limbs, it remains motionless attached to rocks throughout its adult life.
Anatomy
The adult barnacle has two clearly differentiated parts, the upper part or capitulum, and the lower part or peduncle, which would be the part that is attached to the rock.
The upper part, the capitulum, is commonly known as the barnacle's nail, due to the appearance of a series of greyish-white calcareous plates. This claw protects the animal from the attack of a possible predator and, on the other hand, protects it from drying out at low tide when the water level drops and the animal is exposed to the air.
That this part is specially protected is no coincidence: most of the barnacle's vital organs appear under these plates, in what is known as the barnacle's prosoma. Six pairs of cirri and the mouth stand out, the first link in the animal's digestive system. The cirri act as mobile appendages whose function is to capture food from the environment and transport it to the mouth. It is believed that originally they acted as legs that allowed the animal to move.
The chapter presents three movements responsible for coordinating the feeding of the barnacle. A muscular bundle, the cirral, is in charge of the movement of the cirri to search for and capture food; another group of muscles is in charge of elevating the prosoma in order to extend the cirri outside the nail and thus facilitate its function, and a third muscle, the lateral one, allows the flexion of the prosoma and facilitates the transport of food to the mouth. On the other hand, the chapter has another muscle, the adductor, which makes it possible to open and close the nail, facilitating the functioning of the special circulatory system of barnacles, animals that do not have a heart.
The chapter also develops the respiratory function. Through the surface of the thorax, it captures dissolved oxygen from the water and, because it has a low capacity for oxygen transport, the barnacle must develop in rocky coastal areas strongly beaten by the waves, therefore, highly oxygenated.
The barnacle is a hermaphrodite animal, so each individual has two reproductive systems: one male and one female. The male reproductive system is located in the prosoma. It consists of a pair of testicles and a penis that is between the last pair of cirri. The female reproductive system is located on the peduncle and is made up of two ovaries.
Although it may be thought, the barnacle is not capable of self-fertilization, since to reproduce it is necessary for two different individuals to intervene, one acting as a male and the other as a female.
As for the peduncle, it has a cylindrical shape and is covered by a strong skin. Its flexibility allows it to contract, stretch and move in any direction thanks to the action of three muscle bundles. These movements, on the one hand, facilitate the feeding of the barnacle, since they allow it to orient itself in the direction of the current, and, on the other hand, they are of great importance at the time of reproduction, facilitating the approach of the reproductive systems of the two. adults involved in copulation.
The cement gland also appears on the peduncle. When the barnacle is attached to the rocky substrate, this gland secretes a cement that solidifies outside, contributing to a strong adhesion of the animal to the substrate.
The dimensions of the peduncle, contrary to what is believed, are not directly related to the age of the animal, since both its thickness and its length are variable depending on the state of relaxation of the muscles and, mainly, of the place where the barnacle lives (thicker and shorter in areas more beaten by the sea, thinner and longer the barnacles located in cracks or places where the water current hits them laterally).
Many species of barnacles have the largest penises, in proportion to body size, in the entire animal kingdom.
Life Cycle
The reproductive period of the barnacle in Galicia begins in March and ends in September. Between February and March, 10-20% of adult barnacles mate, but it is the second reproductive period, at the beginning of summer, in which the vast majority of the adult population participates.
The larvae released at hatching are incorporated into the marine plankton and after passing seven larval stages they will present a structure that will allow them to adhere to the substrate in a process called fixation. This entire process, from the hatching of the larva to its establishment as a juvenile, lasts approximately two months. This fixation is not yet definitive, this occurs a couple of months later and it is from here when the development of the barnacle begins. It is estimated that they take approximately six months to reach commercial size (25 mm width of head, 4 cm length).
It is important to know that sexual maturity is reached at a shorter length, so it still would not be of commercial interest to barnacles and these allow them to copulate and spawn before being extracted. This problem, so important and detrimental in other marine species, does not present this type of complications here.
Larvae
It has a free-living nauplius, which when it develops becomes a cypris larva. Both are pelagic, and belong, during this stage of their lives, to plankton (specifically meroplankton).
Distribution
It is distributed along the coasts of Peru, Mexico, the British Isles, France, mainland Spain, Portugal, the Canary Islands (Spain), Cape Verde, and Senegal. It is also rarely found in the Mediterranean Sea.
Gastronomy
It is exploited mainly from the north of Spain (Galicia, Asturias, Cantabria, and the Basque Country), Portugal and France (especially in Belle Île), with the Galician coast being one of the best places for this species, which constitutes a product typical of its gastronomy. It is collected manually from the rocks located in the intertidal zone of the estuaries, cliffs, islands, etc., with considerable risk for the operators, locally called percebeiros in Galician or lanpernariak in Basque. Throughout the Cantabrian Sea, barnacles is a fishery with a significant number of shellfish collectors.
The most common way to consume barnacles is by cooking them in salted water, preferably seawater, for just two minutes, enriching the cooking with a bay leaf. They can also be pan-fried.[citation required]
The edible part is the one that forms the peduncle. Its American edible equivalent is the picoroco.
Beliefs
In Europe, until well into the Modern Age it was believed that some species of geese (those of the genus Branta) were the mature metamorphosis of barnacles (called barnacle(s) in English). both these barnacles and those birds); This was one of the ways in which people mocked the meat fast during Lent, since according to Christianity during this period the only meats that can be eaten are fish and shellfish. In this way, the birds called in the same way and even, on occasion, other similar ones (geese, ducks) were classified as fish. Among the arguments for such a curious taxonomy was the fact that barnacles have appendages that resemble feathers and that, as they are migratory birds, their nests and young were not known.[citation needed ]