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).
