Common acorn barnacle

Semibalanus balanoides

The common acorn barnacle is a tiny crustacean cemented permanently to hard surfaces. It feeds by sweeping feathery limbs through the water.

Not a fish · an aquatic neighbor

Water

Saltwater

Rocky intertidal shores and other hard surfaces exposed to moving seawater.

Temperature

Range not established

A dependable species-specific wild temperature range was not established from the reviewed sources, so both values are null.

Size

Up to about 1.5 cm (0.6 in) across

About the size of a pea

Lifespan

About 1–7 years.

Life expectancy varies with place, conditions, and what scientists have been able to observe.

01 · Signature adaptation

What does it do?

Adults remain fixed in place and must live close to neighbors for cross-fertilization. It opens its plates when submerged and withdraws when exposed or threatened.

Its superpowerIt seals itself inside calcareous plates during low tide and danger.

02 · Home coordinates

Where does it live?

North Atlantic and Arctic coastlines, including Europe and eastern North America.

Regions: North Atlantic · Boreal and Arctic coasts

03 · The menu

What does it eat?

Six pairs of cirri form a food-catching net that pulls particles into the mouth.

Filter-feeder: phytoplankton, zooplankton, detritus.

04 · Remember this

Two wow facts

Crustacean cement

An adult barnacle is a crustacean permanently glued to rock rather than a mollusk.

Sources [1]

Living filter

Its feathery cirri capture plankton and suspended particles from passing water.

Sources [1]