Goose barnacles, also known as stalked barnacles, are a type of crustacean that attaches itself to hard surfaces like rocks, ships, driftwood, and pilings. Their name comes from the goose-neck shaped fleshy stalk that supports their shells. Goose barnacles are found in oceans around the world and have been eaten by humans since ancient times.
What do goose barnacles look like?
Goose barnacles have a fleshy stalk called a peduncle that attaches them to surfaces. At the end of this stalk is a calcareous shell made up of plates. The plates surround the barnacle and protect its soft body parts. Goose barnacles come in different colors like green, blue, gray, and pinkish. Their shells can be smooth or ribbed and may have algae or debris growing on them. The size of goose barnacles varies by species, but they are generally 2-10 cm long.
Where are goose barnacles found?
Goose barnacles are found attached to hard surfaces in the intertidal zone of temperate oceans around the world. Some of the most common locations to find goose barnacles include:
- Rocky shores along the Atlantic coasts of Europe and North America
- Pilings of piers, docks, and harbors
- Ships, buoys, driftwood, and other floating debris
- Coastal areas and estuaries of the North and South American Pacific Coast
- Southern coasts of Australia and New Zealand
Goose barnacles need strong wave action or tidal currents to sweep food into their feeding appendages. For this reason, they are rarely found in areas with soft sediment or sheltered bays. Goose barnacles can survive depths up to 600 feet.
How do goose barnacles attach to surfaces?
Goose barnacles cement themselves permanently to surfaces during their larval stage. After fertilization, free-swimming larvae descend to the bottom. They use their antennules to test surfaces and select a suitable place to attach. Then they produce a quick-drying cement from glands in their antennae to glue themselves to the surface. This cement is incredibly strong and flexible enough to withstand wave shock and tidal forces. Once attached, the barnacle cannot move for the rest of its life.
What do goose barnacles eat?
Goose barnacles are suspension filter feeders, meaning they trap tiny food particles floating in the water. Their calcareous plates surround a feathery thorax containing specialized appendages called cirri. The cirri catch plankton like crustaceans, protozoans, fish eggs/larvae, and even bacteria from the water. Barnacles continually wave their cirri to create a feeding current that brings food within reach. Interestingly, goose barnacles can actually change the speed of their cirral beating depending on food availability.
How do goose barnacles reproduce?
Like other barnacles, goose barnacles are hermaphroditic, meaning each individual functions as both male and female. To reproduce, they use their long penis to fertilize nearby barnacles while also receiving sperm from their neighbors. After internal fertilization, the female barnacle broods fertilized eggs inside her mantle cavity until they hatch into nauplius larvae.
These tiny larvae swim and drift with the currents, molting several times as they grow. Within weeks, they find suitable habitat, attach themselves, and metamorphose into the adult form. Goose barnacles reach sexual maturity after about a year. Their lifespan is generally 5-10 years.
Are goose barnacles edible?
Goose barnacles have been eaten by humans since ancient times and are still considered a delicacy in Spain, Portugal, and France. To prepare them:
- The fleshy stalk is removed.
- The body is removed from the shell plates.
- Internal organs are removed.
- The remaining muscle mass and cirri are cooked.
When cooked, the barnacle has a sweet, tender texture and flavor compared to lobster or crab. However, harvesting goose barnacles poses some health risks:
- Eating raw or undercooked barnacles can cause foodborne illness.
- Barnacles are sessile filter feeders and can accumulate toxins or microplastics from the environment.
- Only harvest goose barnacles from unpolluted waters.
Harvesting of goose barnacles
Goose barnacles have traditionally been harvested by rugged individuals who gather them during low tides. However, due to their high value and overharvesting, several countries now regulate the practice.
Spain and Portugal
In Spain and Portugal, goose barnacle harvesting is carefully regulated with licenses and quotas. There is an annual closed season from January 1 to April 30 to allow populations to recover. Both boat and shore gathering are permitted if harvesters have a license. There are size limits, and harvesters must return a certain percentage of undersized barnacles to the sea to support breeding stocks. Enforcement officers monitor activities and dish out hefty fines for violations.
France
France also has an annual closed season from May 1 to September 30 along its Atlantic coast. Gathering is restricted to the intertidal zone within 12 nautical miles from shore. Minimum size limits are enforced. As in Iberia, harvesters must return undersized individuals to replenish breeding stocks. There are also quota limits per region.
United Kingdom
The UK prohibits the removal or disturbance of goose barnacles on shorelines through the Wildlife and Countryside Act 1981. However, it issues a limited number of licenses each year for controlled harvesting from boats beyond low tide mark. All size and catch limits must be observed.
South America
Peru and Chile allow goose barnacle gathering by small-scale fishermen with some regulations. The harvest season coincides with the reproduction season before the closed season from September to December. Minimum size limits are enforced in Peru.
Goose barnacle population threats
Several factors threaten goose barnacle populations globally:
- Overharvesting – Excessive gathering without proper management depletes populations.
- Habitat loss – Coastal development removes rocky intertidal areas.
- Pollution – Contaminants from wastewater, agriculture, and industry can accumulate in barnacles.
- Non-native species – Invasive marine species may outcompete native goose barnacles.
- Climate change – Ocean warming and acidification degrade habitat quality.
Conservation efforts aim to better regulate harvesting, improve water quality, and protect coastlines. Researchers continue monitoring goose barnacle populations for signs of decline. Some groups are investigating barnacle farming as an alternative, sustainable supply to meet demand without harvesting wild populations.
Unique facts about goose barnacles
- Goose barnacles were once thought to be the embryonic form or eggs of geese since they appeared to “grow” on trees and rocks. It was a common medieval belief that geese or barnacle geese hatched from these barnacles.
- While goose barnacles permanently cement themselves to surfaces, some species like Lepas anatifera occasionally use a muscular stalk to reattach themselves in a better location.
- Young Charles Darwin was fascinated by goose barnacles. Studying their life cycle helped formulate his theory of natural selection.
- Because they remain fixed in place, goose barnacles can’t avoid predators like sea stars. Instead, their stalks have abrasive plates to prevent sea stars from climbing up.
- Humans have unintentionally introduced goose barnacles around the world by transporting them on ship hulls. Non-native species are now found in Australia, New Zealand, and the west coast of North America.
Conclusion
Goose barnacles are intriguing crustaceans perfectly adapted to rocky coastal habitats. Their unique morphology and lifecycle has fascinated both scientists and chefs for centuries. While historically overharvested, better management practices in recent decades have helped conserve goose barnacle populations. Looking ahead, a greater understanding of their ecology will be key to monitoring the impacts of climate change and maintaining goose barnacles as a sustainable seafood source.
