Wet Beast Wednesday: mata mata
Buckle up, buccaneers, because it's turtle time. We travel to the swamps and streams of the Amazon in search of this raggedy reptile. The mata mata is truly the world's skrunkliest turt and it has carved out an interesting niche in the world.
(Image: a mata mata out of water. It is a turtle with a light brown shell that has spiked ridges running down it. The feet have webbed toes and claws. The neck and head are disproportionately large and have a ragged appearance. The head is flat and triangular, with small eyes and nostrils on a tubular nose. End ID)
Mata mata refers to two closely related species of freshwater turtle: the Amazonian mata mata (Chelus fimbriata) and Orinoco mata mata (Chelus orinocensis).Prior to 2020,these were classified as the same species and both have a very similar anatomy and lifestyle. Mata matas are large turtles, with a carapace length up to 45 cm (18 in) and weight of 17.2 kg (38 lbs). Their shells have many spines and ridges while the body, especially the large neck and head, has many skin flaps, tubercles, and ridges. The body and shell are primarily brown to black. This has the effect of making the turtle look like decaying bark and leaves, an effective form of camouflage. The nose is very long, with nostrils at the tip, which, when combined with the long neck, allows the turtle to reach the water's surface to breathe while staying on the bottom. The chin has some short sensory barbels growing from it.
(Image: a mata mata in an aquarium. It is sitting on some rocks with its neck outstretched to reach the surface. End ID)
Mata matas are native to the Amazonian and Orinoco river basins, where they prefer slow-moving waters with low visibility, such as streams, backwaters, and swamps. They are primarily carnivorous, but have been known to eat plants, possibly to supplement their diets or by accident. They are sit and wait predators whose hunting strategy is to sit very still among vegetation. Their camouflage allows them to remain unnoticed by prey. When prey draws close, the turtle opens its mouth. This creates a vacuum, drawing water and prey into the mouth. The turtle then closes its mouth, forcing the water out, and swallows the prey whole. Unlike snapping turtles, who have a similar sit and wait hunting style, the mata mata has weak jaws with fleshy lips rather than beaks and thus cannot bite prey into chunks. It therefore has to feed on animals small enough to swallow whole. Their diet consists of small fish, frogs, and invertebrates. Because they inhabit waters with very low visibility, mata matas have very poor eyesight and rely on other senses to tell when prey is near. Mata matas have also been known to herd groups of fish into shallow water before eating. Unlike many other aquatic turtles, mata matas rarely come ashore to bask in the sunlight. They are also very poor swimmers and mostly crawl along the bottom of their habitats.
(Image: a mata mata facing the camera with its mouth open. The mouth is very wide and takes up most of the head. End ID)
Mata matas display sexual dimorphism. Females are generally larger, though not by that much. Males have longer, thicker tails than females as well as a concave plastron (lover shell) as opposed to the female's flat plastron. Mating occurs late in the year, around October. Males will seek out females and engage in a courtship dance that involves playing out the limbs, wiggling the skin flaps, and extending the heat toward the female while opening and closing his mouth. During mating, the male mounts the female. His concave plastron helps him stay on her shell without falling off. The female will emerge from the water to lay her eggs. She will bury them either in sand or decaying vegetation to keep them warm. She then leaves and neither parent provides parental care. The gestation period varies depending on temperature, up to 200 days at low enough temperatures. In other turtle species, the temperature of the eggs determines the sex of the hatchling. I could not find any references describing how or if this is the same in mata matas. Hatchlings have to scramble their way into the water. Juvenile mata matas have pink plastrons that darken to brown as they age. The maximum age of mata matas in the wild is unknown. In captivity, they usually live for 15 years, but sometimes up to 30.
(Image: a juvenile mata mata held in hand. It is held so the underside is facing the camera, displaying the pink color of the plastron. It is smaller than a cell phone. End ID)
Both species of mata mata are classified at least concern by the IUCN, meaning they are not in danger of extinction. Their primarly threat comes from habitat loss as more and more parts of their rivers are taken over fro land development. Mata matas are also edible and sometimes caught for food. Their unusual appearances have made them somewhat popular in the pet trade and wild mata mata are often caught for this purpose.
(Image: an extreme close-up of a mata mata's face. The shape of its mouth makes it look like it has a smug smile. End ID)
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