Invertebrates
Gooseneck Barnacle
Pollicipes pollicipes · also called goose barnacle, percebes, leaf barnacle
On the most storm-lashed rocks of the Atlantic coast, in the strip that is underwater one second and bare the next, grow clusters of what look like tiny reptilian feet: dark leathery stalks tipped with a knot of white plates. These are gooseneck barnacles, and on the coasts of Spain and Portugal people risk their lives to collect them.
Overview
Pollicipes pollicipes is a stalked barnacle — a crustacean, related to crabs, that cements its head to rock as a larva and lives the rest of its life upside down. Instead of the low cone of a common barnacle, it has a tough black muscular stalk that holds a plated feeding head up into the surf. When a wave washes over, the head opens and sweeps out a fan of feathery legs to comb plankton from the water.
The goose that came from a barnacle
The name records a medieval error. The barnacle goose nests in the Arctic, so Europeans never saw its eggs, and seeing long-stalked barnacles on driftwood they decided the geese grew from the barnacles — a belief serious enough that the bird was sometimes classed as fish for fasting days.
Percebes
The stalk is eaten as percebes, a costly delicacy in Galicia and Portugal. The best grow on the lowest, most exposed rock, and percebeiros scramble into the surf between waves to scrape them off — a job that kills and injures gatherers every year. Because the barnacles grow slowly, the fishery is managed with licences, closed seasons, and rotating zones.
Status
The gooseneck barnacle is Not Evaluated globally. It is abundant on suitable coasts but heavily fished in Iberia, where stocks near towns are depleted and held up only by active management and patrols against illegal harvesting.
Gooseneck Barnacle: common questions
Is a gooseneck barnacle a mollusc?
No, although the plated head looks a little like a shell. Barnacles are crustaceans, in the same broad group as crabs, lobsters, and shrimp. A barnacle begins life as a swimming larva that eventually settles head-down onto a hard surface, glues itself in place, and builds protective plates around its body. From then on it lives upside down and feeds by extending feathery legs to sweep plankton from the water. Most familiar barnacles sit in a low volcano-shaped cone, but the gooseneck barnacle instead has a long, muscular, flexible stalk that holds the feeding head up into the waves.
Why is it called a gooseneck or goose barnacle?
It comes from a medieval misunderstanding about birds. The barnacle goose breeds in the high Arctic, so people in Britain and western Europe saw the geese only in winter and never found their nests or eggs. Noticing clusters of long-stalked barnacles on driftwood and ship hulls, and seeing a rough resemblance between the barnacle's stalk and plates and a goose's neck and head, they concluded that the geese hatched from the barnacles. The belief was taken seriously enough that some church authorities classed barnacle goose as fish rather than meat for fasting days. The name stuck to both animals.
What are percebes and why are they expensive?
Percebes is the Spanish and Portuguese name for gooseneck barnacles eaten as seafood, specifically the fleshy stalk, which is briefly boiled in salted water, peeled, and eaten. They are prized in Galicia, Asturias, and Portugal for a concentrated taste of the sea and can sell for very high prices, especially around Christmas. The cost reflects the danger and difficulty of collection. The best barnacles grow on the lowest, most wave-lashed rock, and gatherers must time the swell, work fast between sets of waves, and often abseil or wade into the surf, which every year leads to rescues and deaths along the Atlantic coast.
How do gooseneck barnacles reproduce if they cannot move?
Each barnacle is a hermaphrodite, producing both eggs and sperm, but most still cross-fertilise with a neighbour rather than fertilising themselves. Since neither animal can move, a barnacle ready to breed extends a very long, thin, tube-like organ out of its shell and probes around for another barnacle within reach, often several times its own body length away, and deposits sperm inside it. The fertilised eggs are brooded inside the parent's plates until they hatch into swimming larvae, which drift as plankton for weeks before finding a rock of their own to settle on, usually close to established adults.