Softshell turtles share a similar general appearance to their hard-shell counterparts, but the similarities end there. They have different diets, habitats, and lifestyles, and despite still having a shell, are noticeably different shapes than their distant cousins. So, what are softshell turtles, and how did they come to be?
What are softshell turtles?
Softshell turtles are simply members of the turtle family who traded in their classic hard-shell for a sleeker and softer shell, more suited to an aquatic lifestyle. Their scientific name is Trionychidae, which translates to “three-clawed” and references their distinct three-clawed, webbed feet.
Types and locations
Members of the softshell turtle family are found in North America, Africa, and Asia. There are over 30 subspecies of softshell turtles located across these three continents, each having adapted slightly different characteristics based on their local aquatic habitats.
In North America, softshell turtles are mostly found in freshwater lakes, rivers, and ponds. In Asia, they are found in these locations as well as rice paddies. In Africa, there are softshell turtles that live in the Nile and some have adapted to live brackish water (a mix of fresh and saltwater). Typically, the larger the body of water they inhabit, the larger they will grow to be.
Physical appearance
Softshell turtles are characterized by their sleek appearance, long necks, pointy noses, webbed feet, muddy brown and tan coloring, and lack of hardened scales on their shell. Their flatter shape allows them to be much faster in the water than a hard-shell turtle. Their long necks and pointy noses are used to breathe when they burrow into the sand to rest. They can remain safely camouflage in the mud or sand while keeping their nose above water for air.
While their soft shells provide less defense, they allow them to better regulate body heat and swim through the water at speed. Combined with their webbed feet, their body shape allows them to move up to (and possibly faster than) 22mph in the water. You can think of them as turtle-shaped fish once they are in the water, and this speed allows them to hunt their favorite foods without much trouble.
The soft shells on their backs are described as feeling similar to the back of one’s ear, or supple leather. Although the shells themselves lack the hardened scales present on hard-shell turtles, they still possess a similarly strong ribcage underneath their shells that can protect them from attacks. Due to their preferred habitat being freshwater lakes and streams, the need to play defense against predators declined. Once a softshell turtle has reached maturity, it’s only predators are the occasional alligator and humans.
The coloring of the softshell turtle is primarily a mix of muddy brown and tan. These colors allow them to camouflage themselves when they burrow into the mud or sand at the bottom of their preferred aquatic habitat. It also acts as camouflage when they are swimming and hunting prey, making it harder for them to be spotted until it is too late.
Habitats
Softshell turtles are primarily found in freshwater lakes, rivers, and ponds, but there are two known subspecies in Africa that prefer brackish water and live in rivers close to the ocean. The turtles can adapt to living in fast or slow-moving rivers, and their size is generally related to the size of their chosen body of water. Those found in large, deep rivers or lakes, can grow to be over 3 feet in length.
Asian softshell turtles are also often found in rice paddies as the shallow waters provide a perfect place to hide and rest. Combined with a lack of natural predators, they are able to flourish in these manmade farming plots.
While softshell turtles are faster on land than their hard-shell cousins, they rarely leave the safety of the water. On land, there are predators who would make quick work of a softshell turtle. In the water, they have almost no natural predators. A fully grown softshell turtle only has to worry about running into an alligator when they are in the water as they can easily overpower most other marine life. In fact, humans are responsible for killing the most softshell turtles, whether it be on purpose for food, or inadvertently through agricultural runoff such as pesticides.
Diet
Without any true natural predators, softshell turtles are free to eat what they please. They are almost entirely carnivorous and will eat any fish, tadpoles, mollusks, frogs, worms, or insects that they can get their beaks on. Certain types of softshell turtles, such as the spiny softshell, will also eat any water vegetation available to them, although this is less common across the subspecies.
Hunting strategy
Being the apex predators in their aquatic habitats, soft-shelled turtles hunt food at their own leisure. They are fast and agile enough to chase down fish, and their beaks are incredibly strong. Given the opportunity, a softshell turtle could remove your finger in one bite which means their prey rarely have an opportunity to escape without being mortally wounded.
In addition to actively hunting prey, they will also burrow into the sand or mud and use surprise attacks to catch their prey. They can reveal themselves incredibly fast, and even the most skittish fish are caught off guard by their attacks.
The last feeding strategy employed by the softshell turtle is that of the opportunistic eater. Turtles will swim down to the bottom of the lake, pond, or river, and eat any fish remains they can find. By scavenging the bottom of the water, they can save energy and still find a nourishing meal.
Reproduction and nesting
Softshell turtles are similar to other turtles in their reproductive habits and they lay their eggs on land. The turtles will mate in the water, and the female will move onto land only long enough to lay her eggs. The process involves digging a suitable nesting hole that resides above the flood line of their chosen body of water. Towards the later stages of their development, baby turtles in their eggs begin to breathe through the egg’s membrane and would not survive being underwater during this time.
The female softshell turtles are known to dig several holes before finding one that they feel is suitable for their babies, and the number of eggs laid varies between subspecies. The number of eggs can be as low as 3, or over 50 per nest. Some subspecies will lay eggs 2-3 times a year, and Florida Softshell turtles are known to lay the most eggs of any reptile per year.
The eggs vary in incubation time based on subspecies, but most eggs hatch between 8-11 weeks. Once a mother turtle has laid her eggs, she covers up the hole and never returns. The baby turtles are on their own from this point forward and face many predators on their journey to adulthood. There are animals that find turtle eggs to be nutritious snacks and will actively seek them out. Once they are born, the small turtles are susceptible to attacks from large fish, and will not be truly safe until they reach adulthood.
Interestingly, hard-shelled turtle genders are determined by the temperatures they are subjected to during their incubation period. This is known as TSD, or, Temperature-dependent Sex Determination. This is not the case for softshell turtles whose genders are determined at the time of conception by their genes, similar to humans. Humans and soft-shelled turtles exhibit GSD, or, Genetic Sex Determination.
Evolutionary adaptations
The softshell turtle originated around 250 million years ago when the turtle species was just beginning. Over the past several hundred million years, they have evolved and adapted to their aquatic homes in more ways than one.
Hard and soft shells
Turtles that developed hard shells did so to protect themselves from predators primarily found on land. By spending more time in the water, these early proto-softshell turtles adapted unique qualities that better suited their aquatic habitats. The first and most distinct adaptation, the soft shell, is how we identify them by name today.
The change to a soft-shell allowed several beneficial traits to develop. The thin, soft-shells allowed these turtles to move through the water quickly and made it possible for them to hunt fish. The loss of their hard shells also caused a change in their respiratory systems, which no longer needed to support a heavily armored body. With their change in composition, they were able to hold their breath longer, and dive deeper to find food. They honed this ability over many years, and are able to hold their breath for around 45 minutes to 1 hour today.
This limit changes based on the turtle’s activity level, and a turtle who spends an hour underwater is usually resting. If a turtle is stressed, hunting, or otherwise active, they typically come up for air every 5 minutes. On the other side of the spectrum, a turtle who is brumating (hibernating) will be able to stay underwater for upwards of 8 hours.
Underwater breathing
While softshell turtles living in temperate climates remain active all year long, those in North America will brumate during the colder months. During brumation, a reptile substantially reduces its heart rate and need for oxygen and nutrients. In order for softshell turtles to remain safe and at an appropriate temperature during their brumation period, they have to remain underwater. The turtles cover themselves in mud or sand and keep their head underwater as well.
Turtles do not have gills, so in order to survive colder months, they evolved the ability to take oxygen from water in other ways. The species living in colder climates evolved to absorb oxygen through their skin from the surrounding water. They get 70% of their oxygen this way, and the remaining 30% is obtained by a process called pharyngeal breathing. Even when brumating, the turtle can pump water in and out of its pharynx where a surplus of blood vessels are waiting to extract oxygen from the water. This means that several species of softshell turtles can remain underwater indefinitely.
Swimming speed
Soft-shelled turtles adapted for life in the water, and being able to swim upwards of 22 mph is rare outside of dedicated marine animals. Their sleek, soft shells allow for surprising speed and agility in the water allowing them to catch most prey with ease. In addition to their softer shells, the turtles evolved to have webbed feet which improved their underwater prowess. Their size, swimming ability, and powerful beaks make them apex predators in their habitats.
Human interaction
Softshell turtles can be kept as pets, and are eaten as a delicacy in Asia. Human interaction has left certain species endangered.
Softshell turtles as pets
Softshell turtles are sometimes kept as pets and can be happy in the right conditions. They are more for watching than interacting with, however, as their beaks can break bones. In order for a softshell turtle to be happy as a pet, it will need a large enclosure and the proper environment.
Because these turtles spend most of their time burrowed in the sand or mud, you will need to maintain a space that is not too far from the water’s surface for them to feel safe and to rest. In addition to a shallow section, you will want to also provide them with enough deeper water for them to swim around in. Softshell turtles are cold blooded and need a constant source of heat to keep temperatures in a safe range.
As they tend to be fragile, and aggressive when threatened, these turtles are not usually recommended as pets for families with small children. It is also recommended that you do not hold two turtles in the same enclosure as they are territorial and may kill each other.
Overall, they are expensive, high maintenance, and low interaction for a pet. You should really be a major turtle enthusiast before considering owning one.
Eating softshell turtles
Eating softshell turtles is common in Asia, and is considered a delicacy. Typically, turtles are used to make soup. In China, the use of softshell turtles for soup is so extensive that the Chinese softshell turtle is the most commonly raised species among their turtle farms. Its use in food makes it the “world’s most economically important turtle”.
Other countries also have turtle soup as a delicacy, but opt for hard-shelled turtles such as the snapping turtle.
Endangered species
While softshell turtles are considered apex predators, humans are responsible for certain subspecies becoming endangered. One notable sub specie is the Yangtze giant softshell turtle, located primarily in China. The Yangtze giant softshell turtle is the largest freshwater turtle in the world and became endangered primarily due to pollution and habitat destruction.
Until 2021, there were only 3 recorded Yangtze turtles left in the world, all of whom were male. Recently, it is believed that another female was found in Vietnam, which may save the species.
While this is a sad story, it is fortunately not the case for most species of softshell turtles. Most exist happily in their ecosystem and are not at risk of being endangered. The Chinese softshell turtle is currently listed as vulnerable but is expected to maintain its population due to turtle farms and their economic importance.
