California smoothtongue

Leuroglossus stilbius

FAMILY

Microstomatidae

TAXONOMY

Leuroglossus stilbius Gilbert, 1890, Pacific off northwestern Mexico, Albatross sta. 2997, 221 fathoms (1,326 ft/400 m).

OTHER COMMON NAMES

English: Esperlan, smoothtongue, southern smoothtongue; Spanish: Esperlan, esperlan de lengua suave.

PHYSICAL CHARACTERISTICS

Length about 7.9 in (20 cm), small to moderately sized, elongate; dorsal fin medially placed; adipose fin present; eyes large. Body light to dark, may be silvery.

DISTRIBUTION

Eastern Pacific from Oregon, United States, in the north, to Gulf of California, Mexico, in the south.

HABITAT

Marine. Deep waters, oceanic at depths between surface and 2,265 ft (690 m).

BEHAVIOR

Gregarious, forms large schools.

FEEDING ECOLOGY AND DIET

Benthic and planktonic crustaceans, worms, and tunicates have been recorded in the guts of juveniles. Reported to be preyed upon by tunas off the coast of the United States. Likely to have specialized eyes as those of some close relatives. Eyes are positioned on the top of the head to increase binocular vision, and in each eye a gap in front of the lens increases illumination of the retina, which itself has specialized photoreceptors. These specializations ensure great visual sensitivity in the forward plane and spatial perception, attributes particularly relevant when searching for prey in dim environments.

REPRODUCTIVE BIOLOGY

Spawning occurs in the California Current between December and May. Eggs and larvae are pelagic.

CONSERVATION STATUS

Not listed by the IUCN.

SIGNIFICANCE TO HUMANS

None known.