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2020 Year of the Turtle – the mud turtles

This is a new one for many of you… mud turtles.  Most have never heard of them.  They are very small turtles with oval shaped, domed shells that have hinges similar to box turtles.  There are actually two genera within this family of small turtles, the mud turtles (Kinosternon) and the musk turtles (Sternothurus).  There are two species of each found in Florida and they differ in that the mud turtles have two hinges on their plastron (belly shell) and the musk only have one.  In this post, we will focus on the mud turtles.

The small, but cool, eastern mud turtle.
Photo: Charles Bartlett

As mentioned above, mud turtles differ in that they have two moveable hinges on their plastron.  Also, the scutes (scales) anterior of the anterior most hinge is triangle in shape instead of square.  There are two species of mud turtles in Florida.  The Striped Mud Turtle (Kinosternon baurii) is a resident of peninsula part of our state.  Found from the Apalachicola River to the Florida Keys, this turtle differs from the Eastern Mud Turtle in having three yellow longitudinal stripes on the carapace (though these stripes be faint or missing in the northern part of the state).  The carapace has a concave depression on each side of the backbone and the head is usually striped.  The length of the carapace is usually not more than 4”.

 

The Eastern Mud Turtle (Kinosternon subrubrum) has three subspecies.  The Eastern Mud Turtle (Kinosternon subrubrum subrubrum) is found in northern Florida and differs from the Striped Mud in having a mottled head in lieu of a striped one.  The Florida Mud Turtle (Kinosternon subrubrum steindachneri) also has a mottled head but is found in the peninsula part of the state (but not the Keys).  The Mississippi Mud Turtle (Kinosternon subrubrum hippocrepis) has two stripes on the head and is only found in the far western panhandle.  This species lacks the stripes and concaved carapace.  They too are small, with carapace lengths from 3 – 5 inches.  This species has a much-reduced plastron, similar to snapping turtles.

 

The striped mud can be found in either quiet or flowing waters, where the eastern mud(s) prefer quiet waters with lots of vegetation.  In the Florida Keys numerous striped muds have been found in ditches and roadside ponds.  They have been in brackish water up to 15 ppt.  Stripes are known to make long overland movements during rain and can remain there for several weeks.  It is believed they are seeking nesting areas.  Eastern muds have been known to make overland movements but not to the extent of the striped muds, and many eastern muds are known to not make these trips at all.

 

Both species are known to nest in the spring, but the striped muds have a fall nesting season as well.  Unusual for turtles, male eastern muds are larger than the females.  Male striped muds will have a concave plastron, similar to what the terrestrial turtles (gopher tortoise and box turtles) have.  Both will find sandy spots and lay between one and eight small eggs.

 

Both species are omnivorous.  Striped muds like seeds, leaves, and insects.  Eastern muds consume primarily insects, crustaceans, and mollusks.  Predators are numerous.  As with all turtles, just about everyone consumes eggs and hatchlings.  Being small, adults have their predators as well.  Alligators, snakes, opossums, raccoons, crows, gars, and even blue crabs have been known to take them.  The long wanderings of the striped mud have brought many of them into contacts with cars on highways.

 

The population status is not well known for this group.  There are many research gaps that need to be filled.  They are not currently listed in Florida, though the striped mud is listed as endangered in the Florida Keys.  It appears the primary cause of their decline has been development.

 

These are small turtles but have a big heart!  They can retract into their shells but will take a snip at one’s hand if not careful.  They are pretty cool really and one of the special turtles in our state.