''Austromegabalanus psittacus'', the giant barnacle or ' as it is known in Spanish, is a species of large

barnacle Barnacles are arthropods of the subclass (taxonomy), subclass Cirripedia in the subphylum Crustacean, Crustacea. They are related to crabs and lobsters, with similar Nauplius (larva), nauplius larvae. Barnacles are exclusively marine invertebra ...

native to the coasts of southern

Peru Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the south and west by the Pac ...

, all of

Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...

and southern

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

. It inhabits the littoral and intertidal zones of rocky shores and normally grows up to tall with a mineralized shell composed of

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

. The ''picoroco barnacle'' is used in

Chilean cuisine Chilean cuisine stems mainly from the combination of traditional Spanish cuisine, Chilean Indigenous peoples in Chile, Mapuche culture and local ingredients, with later important influences from other European cuisines, particularly from Germa ...

and is one of the ingredients in curanto.

Description

''Austromegabalanus psittacus'' is a large sessile barnacle that lives in groups on hard substrates. It has a tall cone-shaped carapace composed of twelve large plates made of

microcrystals which are cemented together. The basal disc is firmly cemented to a hard surface. It grows to a height of . There is an opening at the top with a hinged operculum through which the thoracic limbs known as "cirri" protrude. The general colour is dull white with purple and brown markings.

Biology

''Austromegabalanus psittacus'' is a simultaneous

hermaphrodite A hermaphrodite () is a sexually reproducing organism that produces both male and female gametes. Animal species in which individuals are either male or female are gonochoric, which is the opposite of hermaphroditic. The individuals of many ...

. Individual barnacles are fertilised by sperm passed through a slender tube extended by a neighbouring barnacle. The eggs are retained inside the carapace where they are incubated for about three or four weeks. They then hatch into free swimming nauplius larvae which form part of the

plankton Plankton are the diverse collection of organisms that drift in Hydrosphere, water (or atmosphere, air) but are unable to actively propel themselves against ocean current, currents (or wind). The individual organisms constituting plankton are ca ...

. These pass through six stages over the course of about 45 days, the last being a cyprid stage. These larvae are about long and settle on the seabed, usually in the proximity of other barnacles. Often the larvae settle so close together that hummocks are formed as the juvenile barnacles grow. Under these circumstances the calcareous base becomes modified into a more porous, cylindrical form above which the carapaces tower, the central individuals being about twice as tall as the outside ones. The density of the barnacles in the hummocks can be more than 1000 individuals per square metre (11 sq ft). This ability to form hummocks give this species an advantage when they are competing for space with other species of barnacle. It is an

omnivorous An omnivore () is an animal that regularly consumes significant quantities of both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize ...

filter feeder Filter feeders are aquatic animals that acquire nutrients by feeding on organic matters, food particles or smaller organisms (bacteria, microalgae and zooplanktons) suspended in water, typically by having the water pass over or through a s ...

Distribution

''Austromegabalanus psittacus'' is a coastal species found in southern Peru, along the entire length of Chile (including offshore

Juan Fernández Islands The Juan Fernández Islands () are a sparsely inhabited series of islands in the South Pacific Ocean, reliant on tourism and fishing. Situated off the coast of Chile, they are composed of three main volcanic islands: Robinson Crusoe Island, R ...

) and southern Argentina in the intertidal and littoral zone. It is recorded at depths of , but is mostly found at . It is most common in the Los Lagos area in Chile and is harvested for human consumption, mainly in the towns of Calbuco, Carelmapu and

Puerto Montt Puerto Montt (Mapuche: Meli Pulli) is a port city and commune in southern Chile, located at the northern end of the Reloncaví Sound in the Llanquihue Province, Los Lagos Region, 1,055 km to the south of the capital, Santiago. The commune ...

Use by humans and oceanic organisms

Austromegabalanus psittacus 20180130 -Mercado Central fRF

This barnacle forms part of Chilean cuisine. Its meat is highly prized and is one of the ingredients of the Chilean dish curanto. This is traditionally made from various seafood ingredients cooked in a large pit preheated with red-hot stones. Modern cooking methods use a large pot, conventionally heated. Overfishing has reduced the quantities of ''Austromegabalanus psittacus'' available for commercial harvesting. There are plans to cultivate it along the coast of Chile and there are possibilities of exporting it to Japan. In addition to humans, the sea star '' Heliaster helianthus'' and the clingfish '' Sicyases sanguineus'' also eat this barnacle, although the clingfish can only prey on small animals (large ''Austromegabalanus psittacus'' are apparently safe).

References

{{Taxonbar, from=Q2706391 Barnacles Crustaceans of the eastern Pacific Ocean Edible crustaceans Crustaceans of Chile Crustaceans of Peru Crustaceans of Argentina Crustaceans described in 1782