Alex Mustard / Butterfish (Pholis gunnellus) portrait. Gardur, south west Iceland. North Atlantic Ocean.

Alex Mustard / Portrait of a butterfish (Pholis gunnellus) in seaweeds, on a chalk reef. Sheringham, north Norfolk, England, United Kingdom. North Sea

Brent Stephenson / Black guillemot (Cepphus grylle) with a Rock gunnel (Pholis gunnellus) in its bill. Vigur Island, Isafjardardjup, Iceland. July.

Alex Mustard / Butterfish (Pholis gunnellus) portrait. Gardur, south west Iceland. North Atlantic Ocean.

David Fleetham / Longfin gunnel (Pholis clemensi) resting on tubeworm covered rock, British Columbia, Canada, Pacific Ocean.

Terry Whittaker / Black guillemot (Cepphus grylle) brings butterfish (Pholis gunellus) prey to its nest within harbour wall, Portpatrick Harbour, Scotland, May.

Shane Gross / Crescent gunnel (Pholis laeta) peaking out from Colorful rock wall off Vancouver Island, British Columbia, Canada