Animal Diversity Web

Geographic Range

Chelus fimbriatus ranges from the Amazon and Orinoco river systems in Venezuela and Colombia, south to the Tocatina, Araguala, and Xingu rivers of Brazil and Bolivia. Its range also extends west to Equador and Peru, and east into the eastern Amazon river basin. It also occurs on the island of Trinidad.

Chelus fimbriatus has been reportedly introduced into the drainage canals of southeast Florida, though a self-sustaining breeding population has not been confirmed. This introduction may be due to carelesness associated with the pet trade. Possible detrimental effects on Florida's native habitat have not yet been noted or investigated (Ernst and Barbour 1989, Espenshade 1990, USGS Biological Research Division 1999).

• Biogeographic Regions
• neotropical
  • native

Habitat

Chelus fimbriatus prefers shallow, slow moving, turbid bodies of water such as rivers, blackwater streams, swamps, and marshes. The brackish waters of the lower Amazon basin are also inhabited. Soft muddy bottoms are prefered. Chelus fimbriatus is totally aquatic and rarely moves over land (Ernst and Barbour 1989, Espenshade 1990).

• Habitat Regions
• tropical
• freshwater

• Aquatic Biomes
• lakes and ponds
• rivers and streams

• Wetlands
• marsh
• swamp

Physical Description

Chelus fimbriatus is almost surreal in appearance, and at first glance may resemble a pile of debris. Younger animals are salmon pink to reddish-brown in coloration with black to green mottling. As C. fimbriatus matures, the pinkish hues are replaced by faded yellow, washed out browns, oranges, and greys. The carapace has three lengthwise knobby keels. Algae may cover much of the carapace causing the animal to virtually disappear into its surroundings. A fairly large turtle, C. fimbriatus may reach a carapace length of nearly 45 cm. The head is broadly triangular with large lateral flaps of skin. Several hypotheses have been proposed on the possible functions of these flaps. It is known that the flaps have nerves that respond to various stimuli, including motion in the surrounding water. Tubercles on the head near the corners of the mouth and neck, and barbels on the chin, also are reported to have sensory nerves, possibly used in detecting water vibrations and other external stimuli. The snout has evolved into a long protuberance used as a snorkel, minimizing the turtle's movement as only the tip of the snout emerges form the water during respiration. The back of the eyes are lined with a tapetum lucidum, a visual adaptation which reflects light. This is seen also in other nocturnal reptiles. Despite this, C.fimbriatus has extremely poor eyesight. This turtle can sense auditory stimuli obtained through a well developed tympanum on both sides of the head. Chelus fimbriatus is a poor swimmer with legs adapted for walking on the bottom of their muddy habitats. Hatchlings and juveniles can swim awkwardly. Adults rarely leave the bottom of shallow pools and streams. Chelus fimbriatus is only sexually dimorphic after reaching maturity. Males have a concave plastron and rather long, thick tails; females have a flatter plastron and smaller tails. With tail extended, the male's vent (anal opening) is beyond the posterior edge of the carapace; the female's vent is under the edge of the carapace (Alderton 1988, Ernst and Barbour 1989, Kirkpatrick 1992).

• Other Physical Features
• ectothermic
• heterothermic
• bilateral symmetry

• Sexual Dimorphism
• sexes shaped differently

• Range length

  45 (high) cm

  17.72 (high) in

Reproduction

Prior to mating, male Chelus fimbriatus will repetitively extend the head toward the female while opening and closing the mouth.

Movement of the lateral flaps on the head has been observed during this courtship ritual, as well as a hyperextension of the legs from the shell.

• Mating System
• polygynous

Eggs are laid from October through December in the upper Amazon regions. Unlike most Amazonian turtles, which nest in open sandy places, mata matas may excavate their nests in decaying vegetation at the forest edge The eggs are about 3.5 centimeters in diameter and are almost spherical. One clutch may contain 12 to 28 eggs which have a relatively long incubation period. Incubation periods of around 200 days incubated at 28 to 29 degrees Celsius have been noted for captive individuals. (Ernst and Barbour 1989, Espenshade 1990).

• Key Reproductive Features
• iteroparous
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• fertilization
  • internal
• oviparous

• Breeding interval

  Breeding occurs once yearly.

• Breeding season

  Breeding and egg-laying occur from October through December.

• Range number of offspring

  12 to 28

• Average gestation period

  200 days

Young mata matas hatch from their eggs and emerge from the nest on their own, there is no parental care.

• Parental Investment
• no parental involvement

Lifespan/Longevity

There is little information on the longevity of these animals in the wild. In captivity they may live up to 15 years.

• Typical lifespan
  Status: captivity

  15 (high) years

Behavior

Mata matas rarely bask and spend most of their time under water, with the exception of females hauling out onto land to nest. Because of their relatively weak limbs, C. fimbriatus prowl the muddy bottoms of their habitat, and seldom, if ever, swim. This is a solitary species that rarely interacts with members of its own species except when breeding. They are active during the day and night.

Physical characteristics of this turtle correlate closely to its behavioral characteristics. Resembling a pile of debris and using slow and deliberate motions, mata matas blend easily into the surrounding habitat (Ernst and Barbour 1989, Espenshade 1990).

• Key Behaviors
• natatorial
• diurnal
• nocturnal
• motile
• sedentary
• solitary

Communication and Perception

Mata matas have poor vision, but seem to have excellent tactile and auditory senses. The complex folds of skin on their bodies may hold sensory nerves that help to detect motion (see Physical description).

Male mating displays involve touch and physical displays.

• Communication Channels
• visual
• tactile

• Perception Channels
• tactile
• vibrations
• chemical

Food Habits

Chelus fimbriatus is primarily carnivorous. Its diet consists mainly of fish, and aquatic invertebrates. The mandibles are not attached medially, and the relatively weak jaws are unsuited for seizing and chewing prey. Chelus fimbriatus must rely on well developed neck musculature and the hyoid apparatus in the throat. When a potential prey item comes within range of the turtle, the turtle will strike out and open its mouth. Large amounts of water, and the prey item, are sucked in by the low pressure that is created. The mouth is then closed and excess water is expelled. The prey item is swallowed whole. While foraging, C. fimbriatus may trawl the water making lateral movements with its neck and head; at other times the turtles remain still and simply wait for fish or invertebrates to approach. Chelus fimbriatus has also been observed to herd fish into a restricted area and confine them before feeding. The cryptic appearance of C. fimbriatus contributes to its efficiency as a predator; the various neck fringes and algae growth may entice unwary fish to approach in search of food-- and before the prey are even aware of the turtle's presence, it is already too late to escape (Alderton 1988, Ernst and Barbour 1989, Espenshade 1990, Kirkpatrick 1992).

• Primary Diet
• carnivore
  • piscivore
  • eats non-insect arthropods

• Animal Foods
• fish
• aquatic or marine worms

Predation

Mata matas avoid predation by being cryptic and through their large size and thick carapace.

• Anti-predator Adaptations
• cryptic

Ecosystem Roles

Mata matas are important predators of small fish and aquatic invertebrates in the ecosystems in which they live.

Economic Importance for Humans: Positive

Chelus fimbriatus is sometimes collected and sold in the pet trade, and is also captured and eaten by people, though its odd and unappetizing appearance may sometimes save it from the soup pot. As with all organisms, mata matas play a role in the functioning of their local ecosystem.

• Positive Impacts
• pet trade
• food

Economic Importance for Humans: Negative

If Chelus fimbriatus became established in southeast Florida, research would be needed to determine the impact, if any, it might have on native fauna.

Conservation Status

Chelus fimbriatus has no special status. However with rapid destruction of its native habitat, this may not hold true in the future.

• IUCN Red List

  No special status

• US Federal List

  No special status

• CITES

  No special status

Other Comments

TAXONOMY:

Chelus fimbriatus is a member of the Suborder Pleurodira; the side-necked turtles, and is in the family Chelidae ("snake-necked turtles"). Pleurodira bend their neck to the side when pulling it under the edge of the carapace rather than retracting it directly inward, as seen in the Cryptodira, or hidden-necked turtles. Chelus fimbriatus is the sole species in its genus. Although variation in skin and shell color, and in shell shape has been observed, no subspecies are yet identified. The common name "matamata" is said to have the meaning "I kill" in one of the South American native languages. The name Chelus fimbriatus was given by Mertens and Muller in 1934, meaning "fringed turtle".

Contributors

Benjamin Davidson (author), Michigan State University, James Harding (editor), Michigan State University.

References

Alderton, .. 1988. Turtles and Tortoises of the World. New York: Facts-On-File Pub..

Ernst, .., .. Barbour. 1989. Turtles of the World. Washington, D.C., and London: Smithsonian Institution Press.

Espenshade, .. May 1990. Matamata, Chelus fimbriatus. Tortuga Gazette, 26:(5): 3-5.

Kirkpatrick, .. 1992. The Matamata. Reptile and Amphibian Magazine, Sept/Oct, 1992: 34-39.