Over the weekend my family and I visited Amazon World Zoo Park on the Isle of Wight. I saw tons of new stuff and had a great time, but what might have been my favourite creature is one that would have been all but ignored by the vast majority of visitors. I’m talking about the Matamata Chelus fimbriatus*, a bizarre South American river turtle that is as amazing in biology and behaviour as it is in appearance. Amazon World had two of them…
* The name is sometimes written (incorrectly) as Chelus fimbriata.
Matamatas are freakishly weird: they’ve even been referred to as “one of the strangest creatures on earth” (Ernst & Barbour 1989). It’s said that, across parts of the Matamata’s range, particularly ugly women are referred to as matamatas. It’s also said that the word ‘matamata’ means ‘kill, kill, kill’. I have no idea whether this is true (and, if so, exactly what it refers to), but really hope it is. Matamatas occur across the major drainages of northern Bolivia, eastern Peru, Ecuador, eastern Colombia, Venezuela, French Guiana, Guyana, Peru and northern and central Brazil. They also occur on both Trinidad and Tobago: it’s been suggested that they were transported to these islands following big mainland floods (Ernst & Barbour 1989). Their presence in Suriname is unconfirmed.
The large, flattened head is triangular in dorsal view, with huge flaring ‘ear flaps’ that extend laterally from the back of the skull. The eyes are small and placed well anteriorly, close to the base of the short, trunk-like proboscis. This proboscis – superficially similar to that seen in softshell turtles – allows the animal to reach the surface when submerged, and there are lots of photos and paintings that show matamatas engaging in this behaviour. In fact, I think I’ve found another of those ‘artwork memes’. I recall seeing various ‘snorkelling’ matamatas in various children’s books on reptiles. Above, we see a photo (taken by Francis Miller) from the Time-Life International 1963 volume The Reptiles (Carr 1963). Now scroll down… and you’ll note that various bits of art from the 1970s depicted matamatas in uncannily similar fashion.
Two barbels are present on the chin and the jaws are weak and lack longitudinal ridges like those seen in many other turtles. The mouth is really wide, extending right across the face when the animal is seen in front view. The ears are particularly large (by which I mean the tympanic cavities and tympanic membranes).
The Matamata neck is remarkably long (longer than the rest of the vertebral column) and very thick (more on matamata neck evolution and function later). As in other side-necked turtles, the animal folds the neck away to the side when wanting to conceal its head (one question about side-necked turtles: are individuals, or members of a given species, consistent in whether they retract their necks to the left or to the right? Photos show both ‘left-handedness’ and ‘right-handedness’). Tassel-like outgrowths of the skin decorate the sides of the neck [matamata painting above from Burton & Burton (1974); the one below comes from a Macdonald First Library book called Snakes and Lizards. My battered copy is missing all publication details, and I can't find them online].
The brownish or blackish carapace (which can be as much as 52 cm long) is subrectangular or oval and has three bumpy keels running along its dorsal surface. These sometimes do look like keels in the true sense, but in other individuals they consist of rows of tall lumps. The shell’s posterior border is prominently serrated and the plastron is much narrower than the carapace. Musk ducts (ha ha, not to be confused with a certain species of bizarre Australian waterfowl) exit near the rear corner of the ‘bridge’ (the region of the shell that connects the sides of the plastron and carapace). I don’t know how widely appreciated it is that many turtle groups produce strong-smelling musks via specialised glands on the sides of their shells: it’s certainly not as well known as it should be. Algae frequently grows on the Matamata’s shell, aiding its camouflage.
Having mentioned carapace length, it should be noted that 40-50 cm is very large; when the long neck is added, the animal can approach 100 cm in total length. This makes the Matamata the largest chelid, and in fact rather large compared to turtles in general (I tried to find average carapace lengths or total lengths in turtles as a whole – starting with Moen (2006) – but failed). One 1906 record referred to matamatas with carapace lengths of over 120 cm and total lengths of over 220 cm. It would be incredible if such monsters existed, but the data has not been accepted and seems exaggerated (see Pritchard 2008). More on size later!
Matamata populations exhibit a reasonable amount of variation in colour, and there’s been suggestion at times that subspecies should be recognised. Animals from the Amazon are definitely different from those of the Orinoco: the former have rectangular, heavily pigmented shells and very dark markings on their heads and necks, while the latter have oval shells and have pale necks and plastra (Pritchard 2008).
This is a really brief introduction: phylogeny, fossils and feeding behaviour will follow! As usual, try not to ruin all the surprises in advance!!
For previous Tet Zoo articles on turtles see…
- Giraffe-necked giant tortoises
- Giant African softshells – wow
- Gilbert White’s pet tortoise, and what is ‘grey literature’ anyway?
- The goat-eating hot water bottle turtles
- Hard-shelled sea turtles and a diet of glass
- Terrifying sex organs of male turtles
Refs – -
Burton, M. & Burton, R. 1974. The Life of Reptiles and Amphibians. Macdonald and Co, London.
Carr, A. 1963. The Reptiles. Time/Life, New York.
Ernst, C. H. & Barbour, R. W. 1989. Turtles of the World. Smithsonian Institution Press, Washington, D. C. & London.
Moen DS (2006). Cope’s rule in cryptodiran turtles: do the body sizes of extant species reflect a trend of phyletic size increase? Journal of evolutionary biology, 19 (4), 1210-21 PMID: 16780522
Pritchard, P. C. H. 2008. Chelus fimbriatus (Schneider 1783) – Matamata turtle. In Rhodin, A. G. J., Pritchard, P. C. H., van Dijk, P. P., Saumure, R. A., Buhlmann, K. A. & Iverson, J. B. (eds) Conservation Biology of Freshwater Turtles and Tortoises: A Compilation Project of the IUCN/SSC Tortoise and Freshwater Turtle Specialist Group. Chelonian Research Foundation, pp. 020.1-020.10.