The Argentine Snake-necked Turtle, Hydromedusa tectifera
by C. Dee Dillon
The Argentine snake-necked turtle (Hydromedusa tectifera) is one of two South American snake-necked turtles in the genus Hydromedusa (Family - Chelidae). While they appear, at least externally, to resemble the
Australian snake-necked turtles in the genus Chelodina, they are probably more closely related to my personal
favorite, the bizarre Matamata (Chelus fimbriatus). The Hydromedusa genus is characterized by the
extremely long neck and flattened head and neck. It is distinguished from the Australasian snake-necked genus
Chelodina by the nuchal scute which is pushed back completely behind the marginal scutes into the row of vertebral
scutes. Also, an intergular scute completely separates the gulars.
Two species of Hydromedusa are recognized: the Argentine or South American snake-necked turtle
Hydromedusa tectifera, (Cope 1869); and the Brazilian or Maximillian's snake-necked turtle Hydromedusa
maximiliani, (Mikan, 1820). The Hydromedusa tectifera range includes: northern Argentina, Uruguay, Paraguay
and southern Brazil. The range of Hydromedusa maximiliani seems to be limited to the area in and around the
Brazilian state of Sao Paulo, in southeastern Brazil. The two species are easily distinguished. Hydromedusa
tectifera is larger (to over 11 inches), and is strongly keeled with rough vertebral and coastal scutes, becoming
smoother with age. It has a black line on the side of its head and a yellowish-white streak running from its nostrils
to the end of its neck. The smaller H. maximiliani has a smooth carapace reaching a little over 8 inches in
Sexual dimorphism is minimal in H. tectifera. Females reach a larger size, and mature males exhibit a plastral concavity centered on the midline of the rear plastral scutes.
In the wild, H. tectifera uses its snake-like neck to snorkel and dabble in the bottom. It is carnivorous,
preying on small fish, amphibians and snails. The weak jaws are not suited to crushing the shells, but its flat narrow
head helps it clean out the contents by allowing it to place its jaw right inside the shell opening. It is reported to
be nervous and shy and to retain these characteristics in captivity.
My wife and I currently have two specimens in our possession: a female approximately 4 years of age, and a male (we
hope!) that is younger. We just recently acquired the male so I will restrict my comments to the female which we have
had for nearly two years. We have kept her outside from April to November and inside the rest of the year. Pritchard
writes that H. tectifera hibernates during the colder months in the wild. My initial research regarding the
climatic conditions in their home range indicates that it might be possible for them to remain outside all year round
in parts of Southern California. However, I don't intend to risk leaving them outside in the winter until I have
independent confirmation of this.
When housed in our outside pond/enclosure the female comes out of the water to bask infrequently. For the most part
she remains under water and develops a thick blanket of algae on her very sculptured carapace. Somewhat contrary to
other reports she has lost enough shyness to "hand-feed" rather aggressively, and competes well for food even with our
more aggressive Australian snake-necked turtles. Her captive diet consists basically of the same ingredients we offer all of
our aquatic/exotic carnivores: raw and cooked meat (beef, pork and chicken [no raw chicken!]); raw and cooked fish and
shell fish (they love shrimp); feeder goldfish; crickets; and the commercially prepared reptile and fish foods, Tetra
ReptoMin, Purina Trout Chow and All Tropicals.
Feeding time is usually exciting. H. tectifera uses a method of food "capture" that is a combination of the
vacuum action displayed by the Matamata and the snake-like striking of other snake-necked turtles. They are quite
adept at catching free swimming fish, especially in the close quarters of an aquarium!
Both of our specimens seem to be doing well in captivity and have lost some of their shyness. Through hand feeding
them I have discovered that they do indeed have a weak bite and there is no danger to the "hand-feeder" as there can
be with some other chelonians. Overall, they are active, aware, hardy and enjoyable animals.
Pritchard, P. C. H. Encyclopedia of Turtles. New Jersey: T.F.H. Publications Inc., Ltd., 1979.
Obst, F. J., Richter, K., and Jacob, U. The Completely Illustrated Atlas of Reptiles and Amphibians for the Terrarium.
New Jersey: T.F.H. Publications Inc., Ltd., 1988.
Obst, F. J. Turtles, Tortoises and Terrapins. New York: St. Martins Press, 1988.
Originally published in the Tortuga Gazette 28(5): 1-2, May 1992