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Sculpins in the Great Lakes fauna are characterized by wide, flattened heads and by expansive pectoral fins. The lower 2 or 3 preopercular spines on the cheek are short; the upper one is elongate. Adults are benthic fishes with the swimbladder reduced. They are spiny-rayed, but the spines are flexible. Scales are lacking, but may be represented by small dermal prickles, especially on the sides behind the pectoral fin bases. There are scores of species in the North Pacific, smaller numbers in the Arctic Ocean and in the North Atlantic. The large genus Cottus is exclusively freshwater. Myoxocephalus is rarely in fresh water but Myoxocephalus thompsoni inhabits cold fresh waters in the Great Lakes, northern North America and northern Eurasia. Sculpins are bottom dwellers. Various species are found in the Great Lakes and tributaries. The four species divide the lake by depth zonation, from inshore habitats, to intermediate depths, to the deepest waters. The deepwater sculpin adults are restricted to the cold bottom waters of the hypolimnion, where they live in the soft sediment, trying to avoid lake trout and burbot predators by swimming in short bursts near the bottom, then hiding by burrowing just beneath the surface. Deepwater sculpins are descendants of an ancient lineage with a preglacial fossil record in Idaho and modern distribution in glaciated regions. The mottled sculpin lives in the shallowest zone of the Great Lakes and streams throughout the basin. The slimy sculpin lives in cold waters of trout streams and in deeper Great Lakes waters than the mottled sculpin. The spoonhead sculpin lives between the slimy and the deepwater species. In streams, sculpins live on rocky bottoms where they hide under stones in the daylight hours. In the spring, females are attracted to male nest cavities, where they attach the eggs in clusters on the underside of stones, then leave. The male parent then guards the eggs. Sculpins feed on aquatic insect larvae and crustaceans. Larger individuals eat fish and fish eggs, when available.
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