Pacific Acorn Barnacle
ExploreInvertebrate
Pacific Acorn Barnacle
balanus glandula
The Pacific Acorn Barnacle is a tiny animal that sticks to rocks and shells in the ocean. They have a hard shell that looks like a little acorn, and they open up to eat tiny food from the water!
Habitat: Rocky shores and tidal pools along the Pacific coast.
Appearance
The Pacific Acorn Barnacle is a small, whitish-grey cone with a rough, often ridged surface. Its top has a diamond-shaped opening made of four movable plates. It looks like a tiny volcano glued to rocks, distinct from smooth, flat limpets.
KingdomAnimaliaPhylumArthropodaClassMaxillopodaOrderSessiliaFamilyBalanidaeGenusBalanus
Category
InvertebrateRarity
Common
Danger
0/5 · No known danger
Snaps
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Interesting facts
Barnacles are actually crustaceans, which means they are related to crabs and lobsters!
Some barnacles can live for many years, often ten times longer than a pet hamster!
They spend their whole adult life upside down, sticking their head to a rock!
Wow! Baby barnacles swim like tiny shrimp before finding a spot to glue down!
Special abilities
Ability
Super Glue Anchor
Pacific Acorn Barnacle can make an incredibly strong natural cement because of specialized glands that helps them stick to rocks forever.
Ability
Feathery Food Sweeper
Pacific Acorn Barnacle has feathery 'cirri' legs that helps them sweep tiny food particles from the ocean water.
Ability
Shell Fortress
Pacific Acorn Barnacle can close its shell plates because of strong muscles that helps them stay safe and moist during low tide.
Ability
Double Trouble
Pacific Acorn Barnacle has both male and female parts that helps them reproduce even when neighbors are scarce.
Measurements & details
- Length
- 1.5 cm
- Weight
- 0.5 g
- Lifespan
- 10 years
- Appendage Count
- 12
- Colony Size
- hundreds_to_thousands
- Shell Hardness
- 3 Mohs
Diet & Feeding
They sweep tiny ocean critters and plant bits from the water using their feathery legs.
Primary Foods
- plankton
- algae spores
- detritus
- larval invertebrates
Foraging Method
- Filter Feeding
Ecological connections
eaten by
Ochre Sea Star
Pisaster ochraceus
Pries open shells to eat the soft body.
eaten by
Emarginate Dogwinkle
Nucella emarginata
Drills a tiny hole through the shell.
eaten by
Tidepool Sculpin
Oligocottus maculosus
Nips at the feathery feeding legs.
Traits
Social
Social animals live in organized groups, cooperating for survival benefits such as foraging, defense, and raising offspring.
Filter Feeder
Filter feeders obtain nutrients by straining suspended food particles and small organisms from water.
Coastal
Coastal habitats are dynamic environments located along the interface between land and sea, influenced by tides, waves, and saltwater.
Aquatic
Aquatic habitats encompass environments where organisms live predominantly in water, including oceans, rivers, lakes, and wetlands.
Marine
Marine habitats encompass all saltwater environments of the Earth's oceans, supporting an immense diversity of aquatic life.
Also known as
Common BarnacleRock Barnacle
Collections
Safety
Danger
0/5 · No known danger
No special safety notes yet.
Frequently Asked Questions
How long is Pacific Acorn Barnacle?
1.5 cm
How much does Pacific Acorn Barnacle weigh?
0.5 g
How long does Pacific Acorn Barnacle live?
10 years
What does Pacific Acorn Barnacle eat?
They sweep tiny ocean critters and plant bits from the water using their feathery legs.
Where is Pacific Acorn Barnacle usually found?
Rocky shores and tidal pools along the Pacific coast.
How does Pacific Acorn Barnacle hunt?
Filter Feeding
How many arms does Pacific Acorn Barnacle have?
12
How large are Pacific Acorn Barnacle colonies?
hundreds_to_thousands
Snap Map
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Recent Snaps
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Where to spot
Park50 sightings7 species
British Columbia, CA
Porteau Cove Provincial Park
You might spot Barn Swallow, Pelagic Cormorant, and Sea Lion.
View guide →
Park42 sightings5 species
Washington, US
Magnolia Park
You might spot Arctic Butterbur, Red Valerian, and American Brooklime.
View guide →
Aquarium4 sightings4 species
British Columbia, CA
Hardy Island Marine Provincial Park
You might spot Evergreen Huckleberry, Salal, and Pacific Madrone.
View guide →
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