Until the end of the 1990s, this species was largely regarded as a curious holiday guest in our waters, and was rarely observed north of Trondheim. However, from 2004 to around 2007 the distribution was extensive -- both in space and volume. Snake pipefish moved from southern parts of the North Sea and headed north to establish populations in both the Norwegian Sea and the Barents Sea. During the last few years the distribution has been reduced and now is back to normal. In some areas such as the Norwegian Sea the snake pipefish has nearly disappeared again. Snake pipefish usually live hidden among seaweeds, but have also been observed in the open ocean. Its body is long and thin with a smooth surface and vertebrae which are partially covered with thick skin; this gives their body cavity an oval shape. Similar to other species of pipefish, mature individuals have but one dorsal fin. At larval stages, however, they also have thin, membrane-like ventral fins.
They are poor swimmers, but can swim both forward and backward.
The body color ranges from yellowish to brown, with light stripes on its side. Individuals with gray spots have also been observed.
Females can reach over 60 cm in length. Males are slightly smaller, and can reach lengths up to 40 cm.
Snake pipefish are most common in the coastal zone at depths of 10 m or greater. They have been observed at 100 m depths during winter; during summer they may occur at even greater depths.
Mating takes place during June-July, and mating pairs are monogamous. Male and female join vertically in the water while clinging to one another in an S-shape. The female then injects between 200 and 1,000 eggs into the male’s abdomen; he then fertilizes the eggs and retains them until they hatch.
Snake pipefish are not particularly nutritious and are barely edible for humans, fowl, or other fish. Birds feeding on them sometimes choke while attempting to swallow this long, thin, tough fish. Young nesting birds are particularly vulnerable as this fish becomes impossible for them to swallow. Dried snake pipefish skin becomes hard like a dry branch. It has been observed that nesting birds have used dried carcasses of this species as nesting material, although the snake pipefish was originally intended for consumption.