The Shorthorn Sculpin (Myoxocephalus scorpius) is found in Northern Atlantic waters and throughout most of the Baltic, ranging in sizes from 20 to 30 centimeters. It’s a benthic living fish, which means that it lives on the bottom of the sea, where it lays its eggs between the rocks and feeds on crustaceans and small fish. As with many other fish, its eggs are guarded by the male and not the female.
We’ve regularly encountered this fish during our expeditions in the Baltic, all the way up in the Bothnian Bay, which is the most northern part of the Baltic Sea, and a very harsh environment for marine life. The sea in the area is covered by ice for at least four months a year, and because many rivers wash into the bay, salinity is incredibly low. In fact, given that salinity can get as low as 3 to 5‰ (parts per thousand) freshwater species are more common in these waters.
The Shorthorn Sculpin is one of few marine fishes that can survive in these tough conditions.
It is very effective at osmoregulation which controls the balance of water and salts in the body, keeping its body fluids from becoming too dilute or concentrated. This makes it possible to survive in so fresh waters. But the Sculpin also has a very interesting way of adapting to the freezing environment of the Bay: it has anti-freezing proteins! These generally work by binding to small ice crystals to inhibit their growth and recrystallization, thus lowering the freezing point and enabling the Sculpin to survive in subzero temperatures.