Matamata
Photograph by Sean Baker
Introduction
I have always been fascinated by the matamata turtle (Chelus fimbriatus). Their gentle movements are reminiscent of a land tortoise or a chameleon's "leaf in the wind" walk. Their quick suction eating is like that of an alligator snapper and the matamata is one of the largest freshwater turtles.
I first saw a matamata at the Steinhart Aquarium in San Francisco's Academy of Sciences in the early 1970's. As a member of the now defunct Bay Area Turtle & Tortoise Society, I became more familiar with matamatas through talking with fellow cheloniophiles.
It wasn't until the fall of 1988 that I first acquired a 2.5 inch wild-caught matamata, given to me by a friend. I was apprehensive about taking care of this little exotic sideneck, so I wrote letters and called several people in an effort to learn what I could about this interesting turtle. This article is a compilation of what I learned from those communications, my own experiences, and a literature search.
Natural History
Description:
Carapace is rough and knobby. This turtle obtains a maximum straight-line shell length of 18 inches. Each scute is conical and bears well marked concentric growth rings. The head and neck are large and flat, and are covered with numerous protuberances, warts, and ridges. The mouth is extremely wide, and the snout is long. The eyes are small and situated very near the snout (Pritchard, 1967). Juvenile coloration of the carapace and neck is dark brown to mahogany; while the plastron is usually a brilliant salmon in color. As the turtle gets older, the salmon color fades on the plastron to yellows and browns. The throat stays a reddish brown but eventually changes to a tan or brown.
The purpose of the skin flaps on the head and neck is much debated. It is known that these flaps contain nerves that respond to at least two stimuli which are sent back to the brain. One is movement of the flap without being touched, while the other responds to touch. These findings lead to several theories as to how the turtle uses this information, but does not in itself make that determination (Hartline, 1967).
Taxonomy:
Matamatas (Chelus fimbriatus) were first described in 1741 by Barrere as: Testudo terrestris major putamine echinato et striato, sive raparapa. Of the 15 pre- and post-Linnaean names, Chelus fimbriatus was assigned in 1934 by Mertens and Muller. Matamatas represent a monotypic genus of the Family Chelidae in the suborder Pleurodira. Other South American sidenecks in the family Chelidae are the Hydromedusa and Phrynops. The genus Podocnemis from South America is in the Family Pelomedusidae. No subspecific identifications have been made, though some authors have noted color variations from those observed in the field and in captivity. Also observed were differences in shell shape, from oval-oblong to specimens with parallel sides, to others with straight sides that are not parallel but converge towards the head (Pritchard, 1967; Pritchard and Trebbau, 1984).
Range and Habitat:
Matamatas occur in northern South America, including both the Orinoco River and Amazon River basins. Matamatas are highly aquatic and rarely leave the water. Basking or overland movement have not been observed. They are poor swimmers for any distance and typically walk along the bottom. These turtles breathe by extending their neck so that their snout tip just breaks the surface of the water. Matamatas prefer standing or slow-moving water that is usually turbid. A few observations suggest that extended exposure to salt or brackish water is tolerable (Kearney, 1972; Pritchard and Trebbau, 1984).
Food and Feeding:
Matamatas have been reported as having nocturnal feeding habits on the island of Trinidad (Kearney, 1972). Food items include fish, amphibians, freshwater crustaceans, possibly birds and small mammals that get into the water. The matamatas' feeding technique is singularly unique among chelonians. They suddenly extend their head up to the prey, while simultaneously opening their mouth and expanding their throat. These combined movements create a suction action that draws the prey into their now expanded throat; the water is expelled and the prey is oriented for swallowing (Kearney, 1972; Pritchard, 1967; Pritchard and Trebbau, 1984).
Reproduction:
Copulation in the wild has not been described. Nesting takes place from October to December, when 12-28 eggs are laid. Eggs are nearly spherical and 3.5-4 cm in diameter. Length of incubation is approximately 200 days (Pritchard and Trebbau, 1984).
Captive Maintenance
Food and Feeding:
Food of captive matamatas is probably one of the most contested issues in chelonian care. Goldfish are at the center of the debate. I have been told that live goldfish will erect their dorsal fins when sucked up, and that eventually a fin bone will puncture the throat lining, leading to infection and finally killing the turtle. Many goldfish are mass raised in outdoor ponds into which copper sulfate is added to stop the growth of algae. It has been suggested that the build up of copper sulfate in the fish, and therefore the turtle, can lead to a toxic level that kills the turtle. I have been told that goldfish, in addition to many other fish, have thiaminase, a vitamin B1 enzyme which can cause vitamin B1 deficiencies. Also, many fish in the pet trade have a plethora of microscopic pathogens that can infect and kill the turtle. However, I have spoken with one keeper who had fed frozen goldfish exclusively for five years without problems (Formanowicz et al., 1989).
An interesting note on the feeding habits of the matamata was an observation made by individual at a zoo. He saw what appeared to be a herding behavior in one of three turtles in a crescent shaped pool. The turtle would "herd" the fish by walking at an angle along one edge of the pool, causing the fish to swim to one end. Some fish would get by while some ended up between the turtle and the end of the pool, where they were eaten. The other matamatas co-housed with the "herder" also used this same technique later (Holmstrom, 1978). A researcher ran an experiment in a laboratory setting to test this observation, but unfortunately chose to use round tanks. The researcher concluded that matamatas do not herd their prey. I feel that this experiment is moot on this one point. A round tank would not allow the herding into a corner or an end. This same feeding study concluded that with few fish available or other turtles present, each matamata would move around more in search of food (Formanowicz et al., 1989).
Reproduction:
I am aware of only one private turtle owner in the U.S. that has bred matamatas in captivity. His observations are very briefly described here. Two adult turtles, one male and one female, housed together, were observed courting and then mated (unobserved). Eggs were laid in a chamber adjoining the tank. They were incubated and then hatched. One of many significant discoveries revealed in his articles is the need for mild acidification of the egg shell to help decompose the egg, so as to allow the hatchling to escape (Drajeske, 1982; 1983).
Literature Cited
Drajeske, P. W. 1982. Captive breeding of the mata mata turtle (Chelus fimbriatus). 6th Ann. Rep. Symp. Captive Propagation Husbandry July 28-31, 1982.
Drajeske, P. W. 1983. Husbandry and captive reproduction of the mata mata, Chelus fimbriatus (Schneider), Bull. Chicago Herpetol. Soc. 3-4:73-81.
Formanowicz, D. R., Jr., E .D. Brodie, Jr., and S. C. Wise. 1989. Foraging behavior of matamata turtles: the effects of prey density and the presence of a conspecific. Herpetologica 45(1):61-67.
Hartline, P. 1967. The unbelievable fringed turtle. Int. Turtle Tortoise Soc. J. 1(6):24-29.
Holmstrom, W. F. 1978. Preliminary observations on prey herding in the matamata turtle, Chelus fimbriatus (Reptilia, Testudines, Chelidae). J. Herpetol. 12:573-574.
Kearney, P. 1972. Nocturtles of Trinidad. Int. Turtle Tortoise Soc. J. 6:10-33.
Mertens, R. and L. Muller In Rust, H. T. 1934. Sytematische liste der lebenden schildkroten. Blatt. Aquar.-u.-Terrar. Kunde. 45:42-45, 59-67.
Pritchard, P. C. H. 1967. Living turtles of the world. T.F.H. Publications Inc., New Jersey.
Pritchard, P. C. H. and P. Trebbau. 1984. The turtles of Venezuela. SSAR Contrib. Herpetol. 2:101-110.
For Further Reading
Hausmann, P. 1968. Mata mata. Int. Turtle Tortoise Soc. J. 2(4):18-19, 36.
Reeves, M. 1971. The indefatigable vacuum cleaners. Int. Turtle Tortoise Soc. J. 5(1):4-5, 26-27, 30.
Originally published in the Tortuga Gazette 26:(5): 3-5, May 1990
