Ohio is home to two species of softshell turtle: the spiny softshell (Apalone spinifera) and the smooth softshell (Apalone mutica). The spiny softshell is the more widespread of the two, found across much of the state in rivers, large streams, and lakes, while the smooth softshell is far rarer and limited to a handful of river systems. Both look strikingly different from the hard-shelled turtles most Ohioans are used to seeing, with flat, pancake-like bodies covered in leathery skin rather than rigid scutes. That flexible shell is not a deficiency but rather the signature of a highly specialized aquatic lifestyle millions of years in the making.
Two Species, One State
The spiny softshell is the softshell you are most likely to encounter in Ohio. It lives in the Ohio River and many of its tributaries, the Muskingum, Scioto, Great Miami, and Little Miami river systems, as well as Lake Erie and some inland reservoirs. It gets its name from small, spiny projections along the front edge of its carapace, which are most pronounced in adult females. Females are also considerably larger, sometimes exceeding 40 centimeters in shell length, while males tend to be half that size or less.
The smooth softshell is a different story. In Ohio, it is considered a species of concern, found mainly in a few western river drainages. Its shell lacks the spiny projections and has a smoother texture overall. The smooth softshell is also somewhat more of a river specialist, preferring clean-bottomed, moderate-current waterways with sandy or gravelly substrates. Both species have long, snorkel-like noses, webbed feet, and a distinctly flat profile that makes them easy to distinguish from any other turtle in the state.
What Makes the Shell “Soft”
Softshell turtles still have bone underneath, so the shell is not as fragile as it looks. The flat bones of the carapace are structured like a sandwich, with compact bone layers on the outside and inside surrounding a spongy layer of cancellous bone in the middle. What makes the shell distinctive is the outer covering: instead of the keratinous scutes that hard-shelled turtles wear, softshells are covered in a tough, pliable skin reinforced by dense collagen.
Research on the microstructure of this shell has revealed a remarkably engineered arrangement. The outer bone layer contains a plywood-like pattern of structural collagen fiber bundles, with fibers oriented in alternating directions much like the layers in actual plywood. This design gives the shell considerable strength and resistance to puncture despite its flexibility.1Organisms Diversity & Evolution. A plywood structure in the shell of fossil and living soft-shelled turtles (Trionychidae) and its evolutionary implications Comparative studies of embryonic shell development show that softshell turtles lay down denser, more regularly organized collagen in their carapace than hard-shelled species do, and that this strong dermal layer compensates for the absence of rigid scutes. The tradeoff is real: the pliable covering allows greater flexibility and maneuverability in water, while a hard shell would provide better armor on land.2PubMed. Comparative study of collagen distribution in the dermis of the embryonic carapace of soft- and hard-shelled cryptodiran turtles
The result is a turtle built for speed and stealth in the water rather than defense on shore. Softshells are among the fastest-swimming freshwater turtles, and their streamlined shape helps them chase down prey and evade predators in a way that a box turtle or snapping turtle simply cannot match.
Life in Ohio’s Rivers and Lakes
Softshell turtles in Ohio are strongly tied to water. They spend the vast majority of their lives submerged and rarely wander far from a riverbank or lakeshore. Spiny softshells are frequently seen basking on sandbars, mudflats, or partially submerged logs, but they bolt for the water at the slightest disturbance, which makes them far harder to observe up close than a painted turtle sunning on a rock.
Habitat selection matters a great deal to these turtles. Spiny softshells gravitate toward complex river reaches with side channels, islands, and diverse bottom types including gravel and sand. In free-flowing rivers, they select habitats maintained by natural discharge patterns, overwintering in deep pools and spending summers in reaches with side channels and varied structure.3River Research and Applications. Riverine turtles select habitats maintained by natural discharge regimes in an unimpounded large river Juvenile spiny softshells are known to thermoregulate by burying themselves in sandy or gravelly substrate in shallow water, and laboratory tests have confirmed that young turtles actively seek out the warmest available water, preferring temperatures around 34°C when given a choice.4PubMed. Effect of acclimation temperature and substrate type on selected temperature, movement and activity of juvenile spiny softshell turtles (Apalone spinifera) in an aquatic thermal gradient
Smooth softshells in other parts of their range show similarly active movement patterns. Radio-tracking of smooth softshells in an Illinois river found an average daily movement rate of about 142 meters per day, with some individuals moving over two kilometers in a single day. Females tended to move more than males under most conditions, and movement peaked at moderate water temperatures early in the active season. Home ranges averaged about 18 hectares of river channel.5Diversity. Movement and Home Range of the Smooth Softshell Turtle (Apalone mutica): Spatial Ecology of a River Specialist Both species are opportunistic predators, feeding mainly on crayfish, aquatic insects, fish, and occasionally plant material. Their long, flexible necks allow them to strike quickly from ambush positions buried in sand.
Breathing Through Their Skin
One of the most unusual traits of softshell turtles, and one directly relevant to their survival in Ohio’s climate, is their ability to absorb oxygen through their skin while submerged. That thin, vascularized shell covering is not just flexible armor; it functions as a respiratory surface. Blood vessels running close to the skin’s surface allow gas exchange with the surrounding water, supplementing or even temporarily replacing lung breathing.
This ability becomes critical in winter. Ohio’s rivers and lakes get cold, and softshell turtles, like all freshwater turtles in the state, must overwinter underwater. Many hard-shelled turtles can tolerate extended periods without any oxygen at all, switching to anaerobic metabolism and buffering the resulting lactic acid with calcium from their shells. Softshells cannot do this. Research has shown that spiny softshells are among the most anoxia-intolerant turtles in North America. In laboratory tests, five of eight spiny softshells died within 14 days of submersion in oxygen-free water at 3°C. Their blood became dangerously acidic, and lactate levels skyrocketed. Yet in oxygenated water at the same temperature, the same species survived more than 150 days with no problems.6PubMed. Hibernation in freshwater turtles: softshell turtles (Apalone spinifera) are the most intolerant of anoxia among North American species
The implication is that softshells absolutely depend on well-oxygenated water to make it through winter. They are superbly equipped to extract oxygen through their skin, but they have almost no backup plan if that oxygen disappears. This forces them to hibernate in places where the water stays oxygenated all winter: large rivers, deep lakes, and areas with steady current. Shallow, stagnant ponds that might freeze solid or lose their dissolved oxygen are death traps for a softshell.
Smooth softshells have been observed performing a distinctive “push-up” behavior on the river bottom during winter. They partially bury themselves in sand or mud, then periodically raise and lower the back part of their body into the water column. This motion appears to serve a respiratory purpose, flushing away the thin layer of oxygen-depleted water that builds up against their skin and replacing it with fresher water. In laboratory settings, smooth softshells performed these push-ups less frequently when dissolved oxygen levels were high and more frequently when oxygen was lower, strongly suggesting the behavior is a ventilation strategy.7Journal of Herpetology. Aerobic Pushups: Cutaneous Ventilation in Overwintering Smooth Softshell Turtles, Apalone mutica
Nesting and How Sex Is Determined
Softshell turtles in Ohio nest from late May through July. Females leave the water, sometimes traveling a surprising distance, to dig nests in sandy or gravelly banks and sandbars along rivers. A typical clutch contains anywhere from a dozen to over 30 eggs, depending on the species and the size of the female. The eggs are round and have a somewhat brittle shell compared to the leathery eggs of many other turtle species.
One fascinating difference between Ohio’s two softshell species is how the sex of their offspring gets determined. In many turtles, including painted turtles and snapping turtles, the temperature of the nest during a critical developmental window determines whether embryos become male or female. This is called temperature-dependent sex determination, and it means a warm nest might produce all females while a cool nest produces all males. The smooth softshell, however, uses chromosomal sex determination, more like mammals and birds. Its embryos carry sex chromosomes, and the temperature of the nest does not override this genetic instruction.
Research comparing these two systems has found that the gene networks underlying sexual development in turtles with chromosomal sex determination, like the smooth softshell, are more tightly coordinated and less sensitive to temperature variation. In contrast, turtles relying on temperature-dependent sex determination show gene expression that shifts significantly in response to incubation temperature.8Sexual Development. Multivariate Expression Analysis of the Gene Network Underlying Sexual Development in Turtle Embryos with Temperature-Dependent and Genotypic Sex Determination The spiny softshell also uses chromosomal sex determination, which means neither of Ohio’s softshell species is vulnerable to the sex-ratio skewing that climate change may cause in temperature-dependent species like painted turtles.
Threats Facing Ohio’s Softshells
Softshell turtles face a distinctive set of threats that stem directly from their reliance on river habitats and exposed sandbars. Their nesting sites on sandy river banks are particularly vulnerable. A study of softshell nest survival along a river in Louisiana found that all-terrain vehicle traffic was the single most common source of nest destruction, crushing about a third of nests. Nest mortality increased with heavier ATV traffic, and shallower nests were the most vulnerable.9BioOne / Journal of Herpetology. The Impact of ATVs on Survival of Softshell Turtle (Apalone spp.) Nests Ohio’s softshells face similar risks anywhere recreational vehicles are driven on riverine sandbars during nesting season.
Dam construction and hydropower management present a more systemic problem. Dams alter the natural flow of rivers, reducing the sediment mobilization that creates and maintains the sandbars softshells need for nesting. A comparison of spiny softshell populations in a free-flowing river versus a hydropower-regulated river found that the unregulated river supported over seven times more potential nesting habitat. In the regulated river, nearly 80 percent of nests were concentrated at just nine sites, and demographic indicators suggested the population was struggling to recruit young turtles.10River Research and Applications. Hydropower Operations Reduce Alluvial Nesting Habitat and Alter Riverine Turtle Population Demographics Ohio’s rivers are heavily dammed, and these findings are directly relevant to understanding why softshell populations may be declining in some watersheds.
Predation on nests by raccoons, skunks, and other mammals is also significant, and water pollution can reduce prey availability and degrade the clean sand and gravel substrates softshells prefer. Unlike snapping turtles or painted turtles, which tolerate a wide range of water quality, softshells tend to disappear from degraded waterways. Their presence is often considered an indicator of relatively healthy river conditions.
Encounters and Misconceptions
If you spend time fishing or canoeing on Ohio rivers, you will eventually spot a softshell, usually as a flat shape rocketing away from a sandbar as you approach. People sometimes mistake them for something other than a turtle entirely, since the flat leathery body and elongated snout look nothing like the domed, armored turtles they are used to. Others encounter them on a fishing line and are surprised by how aggressively a softshell can bite and scratch when handled. Their long necks give them considerable reach, and they do not hesitate to use it. Handling a large female spiny softshell bare-handed is a good way to get cut by the sharp edges of her shell or bitten by a surprisingly powerful jaw.
A common misconception is that the soft shell makes these turtles fragile or sickly. In reality, the flexible shell is an evolutionary advantage in their aquatic niche. Another misconception is that softshells are easy to keep as pets. Both Ohio species grow large, require spacious aquatic setups with clean water and sandy substrate, and are far more demanding than a red-eared slider. Ohio regulates the collection and possession of wild reptiles, and anyone considering keeping a softshell should check the current Ohio Division of Wildlife regulations before collecting any animal from the wild.
It is also worth noting that softshell turtles are edible and historically were harvested for food and commercial sale. Harvest regulations in Ohio set size limits, season dates, and bag limits to prevent overharvest, but these rules change periodically, so checking the most recent Ohio fishing regulations is essential if you intend to keep one.
An Ancient Group With Deep Roots in North America
Softshell turtles are not recent arrivals to the continent. The family Trionychidae has a fossil record in North America stretching back tens of millions of years. Paleontological work on a group called the plastomenids, known from fossils spanning the late Cretaceous through the Eocene, has revealed that these extinct North American turtles are early relatives of one of the two main softshell lineages. Their discovery significantly closed a gap in the fossil record, reducing an estimated 80-million-year gap in one softshell subgroup’s history down to roughly 30 million years.11Palaeontology. A neglected lineage of North American turtles fills a major gap in the fossil record
The plywood-like bone structure found in modern softshell shells has also been identified in fossil trionychid specimens, suggesting this engineering solution is ancient and has been conserved across the family’s evolutionary history.12Organisms Diversity & Evolution. A plywood structure in the shell of fossil and living soft-shelled turtles (Trionychidae) and its evolutionary implications The softshell body plan, in other words, is not a recent experiment. It is a deeply tested strategy for life in rivers and lakes, one that has persisted through major climate shifts, mass extinctions, and the rise and fall of entire ecosystems. Ohio’s spiny and smooth softshells carry that legacy in every layer of their unusual shells, quietly thriving in the state’s rivers as they have for epochs.