Critter Corner No. 25 – The Spiny Softshell Turtle by George Sly
Previous Critter Corner episodes have discussed the common snapping turtle and red-eared slider. Another interesting turtle species documented during the 2010 Biodiversity Survey at Goose Pond FWA is the eastern spiny softshell turtle. Softshell turtles are so-named because their carapace is covered by a thick, leathery skin rather than the large, keratinized scutes (scales) of other turtles.
This species is quite fascinating because of its interesting adaptations to a highly aquatic lifestyle. Compare the photo above to the bulky stoutness of our eastern box turtle. The softshell is clearly more streamlined with its highly flattened carapace. Reducing friction drag, and thus energy demands, is a significant advantage for animals that move through both water and air. The softshell turtle’s forelimbs are powerfully adapted for paddling through the water. For a turtle, they are quick, agile runners too. It is not unusual, while paddling along in one’s canoe, to be taken by surprise as a group of basking softshells hightail it down an embankment and into the water at your approach.
The nostrils of all the softshell turtle species are set at the end of an elongated, tubular snout and the eyes are placed high on the head. These are in fact common adaptions among highly aquatic animals; think frog and hippopotamus for example. Such features allow the turtles to see and breathe while exposing little of their body to potential predators. Thus equipped, they can hide their body in shallow sands and muds and still have a portion of their head above water for breathing and surveying their surroundings. Additionally, spiny softshell turtles can extract oxygen from the water via blood vessels in their pharynx and cloaca. As a result, they can remain submerged for extended periods of time if so desired.
Indiana is home to two species of softshell turtles; the aforementioned eastern spiny softshell and the midland smooth softshell. Note the spiny, bumpy projections along the front of the carapace or upper shell in the close-up photo. These give the former species its name.
The eastern spiny softshell turtle inhabits large ponds, ditches, lakes, creeks, and rivers. The midland softshell turtle, on the other hand, prefers larger streams and its appearance in small streams or lakes is not common. This species has not been found at GPFWA.
Softshell turtles in our area hibernate during the winter by burrowing into bottom sand or mud. They emerge in the spring and soon mate. Females subsequently lay an average of 12 to 18 eggs. Nests are dug into sand or loose soil near the water during June and July.
The eastern spiny softshell is primarily carnivorous and preys upon crayfish, aquatic insects and sometimes worms, amphibians, and terrestrial insects that fall into the water.
I have found juvenile softshell turtles to be rather complacent but adults are said to be of cranky disposition and prone to bite. Their long necks and horny, keratinized jaws allow them to chomp down with agility. Their claws can also inflict a painful scrape.
Threats to the spiny softshell include pollution of their waters by industrial or chemical wastes, being struck by boats, and loss of nesting sites due to development. Eggs and young are also subject to predation by mammals such as raccoons and skunks.
This species represents just one more of the many interesting, non-avian animals to be seen at Goose Pond FWA. Perhaps during the summer months at Goose Pond, you might want to search the levees and embankments for the sight of this fascinating reptile enjoying a pleasant sun bath.
Spiny softshell turtle by USFWS @ commons.wikimedia.org
Spiny softshell close-up by Kim Padi @ commons.wikimedia.org
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