The spiny softshell turtle, with its distinctive flat, leathery shell and a pointed, snorkel-like snout, is one of North America’s largest freshwater turtle species. This unique appearance often sparks curiosity about their dimensions. Their size is a common point of interest, particularly given their relatively large adult measurements compared to many other turtles.
Typical Size and Key Differences
Spiny softshell turtles exhibit a notable difference in size between males and females, a characteristic known as sexual dimorphism. Females grow significantly larger than males. The carapace, which is the upper part of their shell, is measured to determine their length. For softshell turtles, the carapace is flattened and covered with leathery skin rather than hard, bony plates, distinguishing it from other turtle species.
Male spiny softshell turtles typically reach a maximum carapace length of about 20.3 to 22 cm (8 to 8.7 inches). Their body weight can be around 130 grams (4.6 ounces) at maturity. In contrast, female spiny softshell turtles can grow much larger, with carapace lengths ranging from 43.2 to 54 cm (17 to 21.3 inches). Some females have been recorded weighing as much as 11.3 kg (25 pounds).
Factors Influencing Growth
Several elements contribute to a spiny softshell turtle’s growth and eventual size. Environmental conditions play a significant role, including the availability and quality of food. These turtles are opportunistic feeders, consuming a variety of invertebrates like crayfish and aquatic insects, as well as fish and plant material.
Habitat conditions also influence their development. Spiny softshells prefer freshwater environments such as rivers, lakes, and streams, particularly those with soft, sandy, or muddy bottoms. Water quality, adequate space, and suitable water temperatures are important for their metabolic processes and overall health. The presence of good basking areas, such as sandbars or logs, allows them to regulate their body temperature, which is important for digestion and growth. Genetic predispositions also play a part, as some individuals may naturally have the capacity for greater growth.
Observing Growth and Development
The growth of spiny softshell turtles is a dynamic process that changes throughout their lifespan. Hatchlings typically emerge with a carapace length of approximately 3 to 4 cm (1.2 to 1.6 inches). Juvenile turtles experience a period of rapid growth, which is characteristic of many freshwater turtle species.
As spiny softshell turtles approach maturity, their growth rate begins to slow down. Males typically reach sexual maturity around their fourth or fifth year, while females mature much later, usually in their twelfth or thirteenth year. Once they reach adulthood, growth becomes significantly slower, sometimes almost immeasurable in the largest and oldest individuals. While older turtles are generally larger, growth eventually plateaus.
Spiny softshell turtles can live for over 50 years. Visual cues of their development include changes in shell coloration; hatchlings often have distinct dark spots that may become more blotched or mottled in adult females, while males tend to retain the juvenile patterning.