Tortuga Gazette 34(3): 1-4, March 1998

The Common Snapping Turtle,
Chelydra serpentina

by C. Dee Dillon

Drawing by Robert Savannah, USFWS

Snapping Turtles are not native to California. In fact they are illegal here. California Fish & Game regulations specifically forbid possession or release of any genus or species of snapping turtle. However, they keep turning up in our lakes and streams, sometimes even walking down the street. Because they are illegal (and a threat to native fauna), Fish & Game have a somewhat permanent solution to snappers when captured. When possible CTTC will adopt the otherwise condemned chelonians to knowledgeable people out of state. Because I find these creatures so fascinating I have been involved in the CTTC Snapper Relocation Program for the last few years. Basically I hold them until I can find a willing adopter out of state then make arrangements to have them airlifted to safety! More about the Snapper program later.

There are two genera of snapping turtles each with a single species, Macroclemys temminckii and Chelydra serpentina. The Alligator and Common Snapping Turtles respectively. I will confine this article to Common Snapping Turtles. My Latin interpretation of the name Chelydra serpentina is Serpent Turtle (surprise!). This is undoubtedly due to their long neck and fast strike capability. There are 4 subspecies recognized by both Pritchard and Iverson. I've had at least two if not three of the subspecies pass though my hands and they all seem to have similar characteristics (aggressive, mean and dangerous), so I will not make distinctions between subspecies here. I don't want to paint the wrong picture because these are truly amazing (and beautiful) creatures, but they are certainly dangerous to handle, so treat them with respect if you ever have to handle one.

Common Snapping Turtles have the largest distribution of any turtle in North America. They range from the Rockies east through Southern Canada and all of the US, through Mexico, Central America and into South America as far south as Ecuador, (west of the Andes). Their range is interrupted in a few places south of the border. The four subspecies are distributed geographically through this range.

Common Snappers have an oval shaped carapace that widens a bit toward the back where it is strongly serrated. Coloration of the carapace varies greatly from tan/brown to olive to almost black. I have seen beautiful caramel colored striations on light colored shells that rivaled the beautiful patterns seen on the plastrons of some Asian Spiny Leaf Turtles. The carapace has three keels running longitudinally. The keels are accentuated with knobs or tubercles under each scute. The keels and knobs' size varies by subspecies but all smooth out or wear out with age. Their skin on top is brown to dark brown often with many tubercles on the legs, neck and tail. The plastron is very reduced as in musk turtles with sort of a cross shape. It is light in coloration (yellowish) compared to the carapace. The bridge is very narrow. The skin underneath is light also being yellowish or cream colored. Snappers have large heads with two barbels on the chin. They have very long tails that are covered with three rows of plate like tubercles that remind me of the growths on Stegosaurus. No significant sexual dimorphism has been noted. They all can emit secretions that generate a strong musk turtle-like odor when threatened or aroused.

Snapping Turtles inhabit all bodies of water without too much discrimination. There may be some slight preference for muddy bottoms within which they can hibernate and/or lie in ambush for unsuspecting prey much like Soft Shelled Turtles. They are very cold tolerant and much of the literature contains references to observations of snapping turtle movements under iced up lakes, rivers or streams! They are a highly aquatic species that basks only occasionally in the southern portion of its range and somewhat more in the northern sections. They spend most of their time on the bottom, but do occasionally make long overland journeys.

Snapping turtles are not what I would classify as picky eaters. In the wild they eat just about everything they can catch, including but not limited to: fish, frogs, crabs, snails, insects, carrion, vegetable matter, water fowl and small reptiles and mammals. This includes other snapping turtles and snakes! My experience with them in captivity supports this fully. They are great for disposal of whatever our cats drag in the house! It is interesting to note that wild caught or deceased snappers have been found with as much as 40%-50% vegetable matter in their stomachs. The young pursue their prey with more vigor (or wasted energy) than adults, which spend more time lying in ambush for innocent prey. As do other aquatic turtles, snappers consume small prey whole and tear larger animals to pieces with their strong claws. They capture prey with a blindingly quick thrust and pharyngeal expansion very similar to Snake Necked and Side Necked Turtles. Adults will drag live prey into the water to drown, (this includes water fowl), which can be mildly hazardous to the snapper due to the clawing and biting done by the prey. Snappers have also been observed eating on land, though I suspect this is a rare occurrence.

Ernst, Lovich & Barbour report that male & female snappers reach sexual maturity at about 8 inches in carapace length. This varies with region but their appears to be a correlation between larger size at sexual maturity and the further north the animal. They mate from about May to November throughout the range but have been reported to nest almost exclusively between 15 May and 15 June with females in the Southern ranges starting somewhat earlier and females in the North starting somewhat later. This leads one to believe that the females may store viable sperm or fertilized eggs across seasonal boundaries, (they must be doing something with all that sperm!). Most nests are laid within to feet of water but some females have traveled as far as 2 miles round trip to lay their eggs. Twenty to forty eggs are typical with clutch sizes larger for larger females and in the more northern ranges, (to aid survival in the harsher climates no doubt). Incubation periods vary across the range significantly, from as little as 55 days to as much as 125 days. As with other turtle eggs the warmer they are the faster they "cook". Hatchling sex determination is temperature dependent as with many other species of turtles and tortoises. However, the relationship between temperature and sex ratio produced is not as straight forward as you might think. Ernst, Lovich & Barbour report that 20° C produces only females, as does 29-31° C. Temperatures in between the two extremes produce both sexes, except 23-24° C which produces only males.

The life span has been estimated at 30-40 years. They live longer in the northern reaches of their range. A 75 pound adult is a giant. Thirty pounds is the average adult size but 40-60-pounders are not uncommon (20 pounds is about the biggest I've handled). As hatchlings they are preyed upon by large birds, alligators, large fish, snakes and other snapping turtles! Adults are prayed on mostly by man, but alligators, otters, coyotes and bears also feed on snappers. Brooks et al., 1990, report that almost all snapping turtles have leeches attached to their skin, particularly in the limb sockets. Captivity must agree with snappers in this respect because of the 20-25 that I have adopted I've yet to find a leech. On the other hand, snappers don't encourage close inspection!).

The animals we hold/adopt come from a variety of sources. Some have come from Castaic Lake, some from private owners that lose interest in them when they get too big to turn around in the aquarium, some of them are found walking down the street, (having escaped from somewhere), and some of them come from the Humane Society, (origin unknown). We have had Common Snappers and Alligator Snappers ranging in size from 5 to 13 inches, the largest was about 20 lbs. Most of them are about 7 to 9 inches in carapace length and 5-8 lbs. This corresponds to the size where they go from cute to scary and really start to become unmanageable indoors or in small outdoor enclosures. They are very aggressive in their self-defense and will often snap/strike at anything. When approached or threatened the "hump up", hiss and emit a musky odor. They will also cock or rotate their carapace to face the danger much as a Nile softshell did to avoid the bite of a crocodile that I saw on a TV documentary. They can strike straight out or to the sides, but most amazingly, (and dangerously), they can strike back across their carapace toward the rear of the shell with their head upside down. Some I have handled have reached as far as two-thirds of the way back to the rear of the carapace. This can make handling them very exciting! Their shells are usually very slippery also. Handling them just by the tail is relatively safe but can severely injure the turtle. I use a combination of my left hand on the rear of the carapace and my right hand on the tail as a backup and I try to keep them close to the ground so they don't have for to fall if I lose my grip, (accidentally or intentionally!). The only close call we have had was when packaging a particularly unhappy 10-11 inch animal that didn't want to go into the burlap sack my wife was holding. It came within a 1/4 inch of her hand. Needless to say we have altered our bagging method. I find them to be incredible animals and very prehistoric looking even if they are New World chelonians. Not recommended as pets, especially by California Department of Fish and Game!

REFERENCES

Pritchard, Peter C. H. 1979. Encyclopedia of Turtles. T.F.H. Publications, Inc. Ltd., New Jersey.
Carr, Archie. 1952. Handbook of Turtles. Cornell University Press, Ithaca, New York.
Ernst, Carl H., Lovich, Jeffrey E. and Barbour, Roger W. 1994. Turtles of the United States and Canada. Smithsonian Institution Press, Washington, D. C.
Iverson, John B. 1992. A Revised Checklist with Distribution Maps of the Turtles of the World. Richmond, Indiana.