About Pholis gunnellus (Linnaeus, 1758)
This species, commonly known as both the rock gunnel and the butterfish (scientific name Pholis gunnellus (Linnaeus, 1758)), is frequently confused for an eel because of its flattened, elongated body shape. Fully grown adult rock gunnels can reach up to 30 cm in total length, while the maximum published standard length for this butterfish is 25 cm (9.8 in). A long dorsal fin runs along the creature’s body starting just behind the head, and this fin is supported by soft spiny rays. Its anal fin starts approximately halfway along the length of the body. The rock gunnel has a relatively small head, with a protruding lower jaw and an upward-turned mouth. Its body coloration is extremely variable, ranging across shades of yellow-green, brown, and crimson. A row of 9 to 13 dark spots, each outlined by a pale ring, runs along the length of the dorsal fin. The rock gunnel occurs in the coastal waters of North America and Europe. In the western Atlantic Ocean, its range extends from Labrador and Greenland south to Delaware Bay; in the eastern Atlantic Ocean, it ranges from the Kanin Peninsula south to the Bay of Biscay. Across this range, the species can be found from the intertidal zone down to depths of more than 100 m. Rock gunnels occupy sheltered habitats hidden by rocks and algae, both above and below the waterline. This shelter likely protects them from their natural predators, which include seabirds, other fish, and marine mammals.
