Fish
Gunnel
Pholidae · also called gunnels, butterfish
Turn over the right rock in a rocky tide pool at low tide, and a gunnel might be waiting underneath, thin and eel-like, perfectly content to sit out the hours until the water returns as long as its hiding spot stays damp. Most people walk right past one without ever knowing it was there.
Overview
The gunnel, family Pholidae, is a thin, eel-like intertidal fish found along rocky, cold-temperate coastlines of the North Pacific and North Atlantic. Its flattened body lets it slip into narrow crevices, and it can survive extended periods stranded out of water at low tide.
Built to wait out the tide
Rather than needing to stay submerged, a gunnel simply tucks itself beneath a wet rock or into damp seaweed when the tide recedes, an adaptation that turns what would be a crisis for most fish into a routine, twice-daily inconvenience.
Status
Least Concern — common and widespread across suitable rocky intertidal habitat throughout its cold-temperate range.
Gunnel: common questions
How does a gunnel survive being stranded out of water at low tide?
A gunnel can tolerate being out of water for a surprisingly long time provided it remains in a damp, sheltered location such as beneath a wet rock or within moist seaweed, an adaptation that allows the fish to simply wait out low tide in relative safety rather than needing to remain fully submerged at all times.
Why does a gunnel have such a thin, flattened body?
A gunnel's long, laterally compressed body shape allows it to slip into narrow rock crevices and beneath stones far more easily than a more typically shaped fish could manage, an adaptation well suited to its secretive, crevice-dwelling lifestyle within the rocky intertidal zone.
Do gunnels take care of their eggs?
In several gunnel species, a parent fish remains coiled around a mass of eggs deposited in a sheltered rock crevice, providing a degree of ongoing protection during development rather than abandoning the eggs immediately after laying, a parental care behaviour not universal among small intertidal fish.
Where can you find a gunnel?
Gunnel species are found along rocky, cold-temperate coastlines, particularly across the North Pacific and North Atlantic, generally sheltering beneath rocks, in seaweed, or within crevices in the intertidal and shallow subtidal zone, making tide pool exploration one of the more reliable ways to encounter one.