Sculpin, pygmy

Cottus pygmaeus (or Cottus paulus)

phylum: Chordata

class: Osteichthyes

order: Scorpaeniformes

family: Cottidae

status: Critically endangered, IUCN Threatened, ESA

range: USA (Alabama)

Description and biology

The pygmy sculpin is a small freshwater fish, averaging less than 2 inches (5 centimeters) long. It has a large head and spotted fins. Young pygmy sculpins have a black head and a grayish-black body. The adult sculpin has a lighter body and a white head with a few dark spots. These fish feed on a variety of insects, snails, and small crustaceans such as crabs.

Male and female pygmy sculpins both darken in color while breeding. Males become almost black and have a reddish-orange tinge along their dorsal (back) fin. Females may spawn (lay eggs) at any time during the year, but do so mostly in spring and summer. Sometimes two or three females form a communal nest by laying all their eggs on the underside of a single rock. Biologists (people who study living organisms) believe a male then guards this nest until the eggs hatch.

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Habitat and current distribution

Pygmy sculpins are found only in Coldwater Spring in Calhoun County, Alabama. Biologists estimate that about 1,000 sculpins inhabit the spring run (small stream or brook) and another 8,000 inhabit the spring pool. Both the pool and the run have sand and gravel bottoms. The temperature of the water in each is a constant 61° to 64°F (16° to 18°C).

History and conservation measures

The pygmy sculpin was discovered in 1968. Because of its restricted range, it is especially vulnerable. Even though its population numbers seem high, the species could be wiped out if a natural or man-made disaster occurs at its site.

Conservationists (people protecting the natural world) believe the pygmy sculpin is indeed in danger. Evidence indicates that the aquifer (underground layer of sand, gravel, or spongy rock that collects water) that feeds the Coldwater Spring is becoming polluted.