Barnaclebill Blenny: A Face in a Barnacle Shell

The barnaclebill blenny is a tiny, charming reef fish that makes its home inside an empty barnacle shell, poking its little face out to watch the world go by. Spotting one takes a close look, but it's one of the reef's cutest residents. Here's how to find one near Jacó, plus five fun facts.

Barnaclebill Blenny · Hypsoblennius brevipinnis

How to spot the barnaclebill blenny near Jacó

Scan clusters of barnacles and small holes on rocks in the shallows. The barnaclebill blenny backs into an empty shell and leaves only its head showing, with its big eyes and little fringed crest. Look for a small face that suddenly ducks out of sight — that's your blenny pulling back into its shell.

5 fun facts about the barnaclebill blenny

• A shell for a house. It shelters and nests inside empty barnacle shells and small holes, backing in so only its head sticks out.
• A fringed crest. Like many blennies, it has small branched tabs, called cirri, above its eyes — a bit like tiny feathery eyebrows.
• Homebody with a view. It rarely strays far from its shell, darting out to grab food or chase a rival, then ducking right back in.
• A devoted dad. The male guards the eggs laid inside his shelter, fanning them with his fins to keep them clean and oxygenated until they hatch.
• Small but bold. For such a tiny fish, it's surprisingly feisty, defending its little shell home against neighbors much larger than itself.

The barnaclebill blenny is just one of many characters down there. See the whole cast in our Snorkel Jaco fish directory, or read real guest photos and reviews on the Snorkel Jaco reviews.