Reptiles
Matamata Turtle
Chelus fimbriata · also called matamata, mata mata
The matamata is a turtle that has committed completely to being unseen. Everything about it — the ragged skin flaps, the algae-crusted shell, the flat leaf-shaped head, the snorkel snout — is built so that a fish will swim right up to what it thinks is a heap of forest debris, and be gone in a flash.
Overview
Matamatas live in the slow, tannin-stained “blackwater” rivers, swamps, and flooded forests of the Amazon and Orinoco basins. They prefer shallow water where they can rest on the bottom with the snout reaching the surface, and they are almost entirely aquatic — poor walkers on land, they emerge only to lay eggs. They are nocturnal and solitary, and they move very little, sometimes staying in the same spot for days.
The disguise
The matamata is one of the most extreme cases of camouflage in a vertebrate:
- A broad, flat, triangular head and a long neck, both fringed with flaps, ridges, and tubercles of skin that break up the outline and mimic bark and dead leaves.
- A rough, deeply ridged carapace, brown and often overgrown with algae.
- Colouring matched to sunken wood and leaf litter.
The strike
The matamata cannot pursue prey — its legs are weak and it has no claws for gripping fish — so it ambushes. It waits, half-buried, until a fish comes close, then executes a gape-and-suck strike: the mouth flies open and the throat expands so fast that water rushes in, carrying the fish with it, in roughly 0.02 seconds. The mouth then closes to a slit, the water is expelled, and the prey is swallowed whole and alive. It is one of the quickest feeding movements known in any reptile, and it needs no biting force at all.
To find prey in murky water, the matamata relies less on its weak eyes and more on vibration and pressure sensing through the skin flaps and neck, detecting a fish before it can see one.
Reproduction
Females leave the water at night in the rainy season to lay clutches of around a dozen brittle-shelled eggs on the bank, then return. The eggs incubate for about 200 days, and the hatchlings are miniature versions of the adults, already leaf-shaped and cryptic.
Status
The matamata is Least Concern and widespread. It is not eaten to any great extent (the meat is not prized), but it is collected for the international pet trade, where its strange looks make it valuable. Localised over-collection and the pollution and clearing of blackwater habitat are the main concerns for particular populations.
Matamata Turtle: common questions
Why does the matamata look like a pile of leaves?
Because that is its entire hunting strategy. The matamata is a sit-and-wait ambush predator that cannot chase fish, so it relies on being invisible. Its flattened, triangular head and long neck are fringed with irregular flaps and warts of skin; its rough, ridged shell is usually coated in algae; and its brown, mottled colouring matches the leaf litter and sunken wood of a tropical blackwater stream. A matamata lying half-buried on the bottom is nearly impossible for a fish — or a person — to pick out.
How does the matamata eat if it never chews?
By suction. When a fish drifts within range, the matamata suddenly opens its huge mouth and rapidly expands its throat and the floor of its mouth, dropping the internal pressure so fast that water — and the fish — is sucked straight in, in about two hundredths of a second. It then closes its mouth on a small gap, letting the water flow back out while trapping the prey, and swallows it whole. Its jaws are weak and its "teeth" are just ridges; the strike does all the work.
How does the matamata breathe without giving itself away?
Its snout is drawn out into a thin tube with the nostrils at the tip, working as a built-in snorkel. The turtle can rest motionless on the shallow bottom and simply raise the very end of its snout to the surface to take a breath, without moving its body or breaking cover. It can also absorb some oxygen through the lining of its throat and cloaca, extending the time it can stay submerged.
Do people keep matamatas as pets?
Yes, they are sought after in the reptile hobby for their bizarre appearance, but they are a challenging animal — they need a large tank of warm, soft, acidic (blackwater) water, a diet of whole live or thawed fish, and do not tolerate handling or bright light well. Wild matamatas are collected for this trade across South America, and while the species is currently classed as Least Concern, unregulated collection is a local concern, and some populations are protected.