Facts: The Rock Gunnel

The rock gunnel, also known as the butterfish because of its slippery skin, is a small, eel-like amphibious fish that inhabits the rocky coastlines of the North Atlantic Ocean. These fish are found from Iceland and Scandinavia and south to the northern bay of Biscay in Europe. They may also be spotted near Greenland and from Canadian waters to Delaware Bay in the United States. Rock gunnels have a long, laterally compressed body with a small head, thick fleshy lips, tiny conical teeth, and almost upward-looking eyes. A dark stripe runs through each eye, and their coloration ranges from yellowish to olive green to reddish brown, often with faint vertical bars or mottled markings. There is a row of 9 to 15 black spots outlined in white along the base of their long dorsal fin. Their spiny dorsal fin extends the entire length of their body. Their pelvic fins are minute. Their tail fin is rounded. Their underside is pale. This species is well adapted to life in the intertidal zone. Rock gunnels can be found hiding beneath rocks, among seaweed, inside crevices, and in tide pools. They most commonly occur in shallow coastal waters down to about 130 feet deep, but they have been recorded at depths approaching around 600 feet over rocky, sandy, and muddy bottoms. During the winter, intertidal individuals move into deeper water. They can survive out of water during low tide by breathing air and remaining hidden. Rock gunnels are most active during dawn and dusk, feeding on amphipods, shrimp, other crustaceans, marine worms, mollusks, and other small invertebrates. In turn, they are an important food source for many predators, including cod, pollock, seabirds, and otters. Breeding takes place during the winter months, typically from November through April. Females lay 80 to 200 eggs in sheltered locations, such as rocky crevices and broken shells. The parents take turns guarding the developing eggs, sometimes rolling the eggs into compact clusters for protection. In cold coastal waters, the eggs require approximately 8 to 10 weeks to hatch. The largest rock gunnels can reach about 12 inches long. They have been recorded to live up to 12 years. For more marine facts, click the SUBSCRIBE button!!