The mata mata, mata-mata, or matamata (Chelus fimbriata) is a South American species of freshwater turtle found in the Amazon basin and river system of the eastern Guianas. It was formerly believed to also occur in the Orinoco basin, western Guianas and upper Rio Negro–Branco system, but in 2020 these populations were found to belong to a separate species, Chelus orinocensis (Orinoco mata mata).
Taxonomy
The mata mata first became known to western scientists when it was described by French naturalist Pierre Barrère in 1741 as a "large land turtle with spiky and ridged scales" (translation). It was first scientifically described as Testudo terrestris in 1765 by Spanish zoologist Fermín Zanón Cervera, but the same scientific name was used for describing the Greek tortoise by Peter Forsskål posthumously in 1775. In 1783, the mata mata was scientifically described again, this time as Testudo fimbriata by German naturalist Johann Gottlob Schneider. In 1805, it was moved to its own genus as Chelys fimbriata by André Marie Constant Duméril. From the mid 1700s to the late 1800s, altogether 15 different scientific names were used for the species. Since the late 1800s, most authorities have used the name Chelys fimbriata. In 1963, the International Commission on Zoological Nomenclature resolved the issue of Testudo terrestris (Fermín 1765) by declaring it a nomen oblitum (meaning that only Testudo terrestris Forsskål 1775 is valid and a synonym for the Greek tortoise), while also declaring that Chelys fimbriata is a conserved name for the mata mata. In 2020, this was supported by a genetic analysis, which showed a deep split between two of its populations. The authors proposed that the mostly Orinoco population be assigned to a new species, Chelus orinocensis, with the Amazon population retaining the C. fimbriatus. However, C. fimbriatus is absent from the upper Rio Negro–Branco system (the northernmost part of the Amazon basin), which instead is inhabited by C. orinocensis.
The mata mata's brown or black, oblong carapace can measure up to at adult age. The plastron and bridges are cream to yellow or brown.
Behavior
thumb|left|Head, in profile
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The appearance of the mata mata's shell resembles a piece of bark, and its head resembles fallen leaves. The mata mata thrusts out its head and opens its large mouth as wide as possible, creating a low-pressure vacuum that sucks the prey into its mouth, known as suction feeding. and fish.
Mata mata turtles use a specific method of seizing their prey. They will move the prey into shallower areas of water, surround the prey, and wave their front legs to prevent them from escaping. Once surrounded, the mata mata turtles will open their mouths and contract their pharynx, causing a rush of water that pushes the prey into their mouth.
In captivity
thumb|right|On exhibit at the [[North Carolina Museum of Natural Sciences]]
Mata mata turtles are readily available in the exotic pet trade and are quite expensive to obtain. Due to their unique appearance, they make interesting display animals. They also grow quite large. However, mata matas are not active hunters, so, like the alligator snapping turtle, they need less space than a large, active species.
As with all aquatic turtles, water quality is one of the keys to keeping this species successfully in captivity. Warm, acidic water is the best type used with a high tannin content that should be maintained all year round. Moderate to heavy filtration is recommended. Author David Fogel considers his captive mata mata turtles to be quite intelligent. For example, he has observed one turtle positioning itself near the spray bar of the aquarium at feeding time so that floating food is pushed beneath the water's surface where the turtle can catch it more easily.