Spiny softshell

Apalone spinifera

SUBFAMILY

Trionychinae

TAXONOMY

Trionyx spiniferus LeSueuer, 1827, New Harmony, Posey County, Indiana, on the Wabash River. Six subspecies are recognized.

OTHER COMMON NAMES

English: Goose-neck turtle, leatherback turtle; French: Tortue luth, tortue-molle a épines; German: Lederschildkröte; Spanish: Tortuga-casco suave espinosa.

PHYSICAL CHARACTERISTICS

This is a medium-sized softshell with spiny protuberances on the anterior rim of a drab olive carapace. A pattern of dark circles, which is especially distinct among the males, fades in the adult females. At least two pairs of callosities (hyo-hypoplastral and xiphiplastral) are present in adults.

DISTRIBUTION

Northern Mexico across most of the southern, central, and eastern United States to the Great Lakes region of southern Canada.

HABITAT

Slow-moving rivers, shallow streams, and large ponds and lakes. BEHAVIOR

This species may remain buried at the bottom of its aquatic habitat for most of the day; however, it occasionally basks on sandbars or steep riverbanks. The spiny softshell remains submerged for long periods by absorbing oxygen through the skin and lining of the throat while carbon dioxide diffuses across the skin. In northern regions, this species hibernates beneath the ice for several months each winter.

FEEDING ECOLOGY AND DIET

These turtles are predominantly carnivorous, ingesting all available aquatic animals; however, plant material including acorns and leaves is also consumed. In Iowa, crustaceans, fish, and insects were the most important food items, but plant matter was found in 61% of all turtles sampled.

REPRODUCTIVE BIOLOGY

Mating occurs in the early spring and eggs are generally laid in June and July. The brittle, spherical eggs are approximately 1.1 in (28 mm) in diameter. At least one clutch of four to 32 eggs is produced annually. The eggs hatch in late summer and hatchlings emerge in the autumn to hibernate underwater.

CONSERVATION STATUS

Not threatened. The widespread distribution and relative abundance of this species in its preferred habitats suggest that it is not currently at risk. Because these turtles are dependent upon high levels of dissolved oxygen in their aquatic environment, water pollution may be the most significant threat to softshell populations.

SIGNIFICANCE TO HUMANS

This species may be consumed locally; however, it is collected in large numbers for sale in Asian food markets in large North American cities and for export. Hatchlings are often available in the pet trade. ♦

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