Common name: keelback, freshwater snake
Scientific name: Tropidonophis mairii
Conservation status: This species is listed as Least Concern in Queensland (Nature Conservation Act 1992).
Keelbacks are Australia's only non-venomous, semi-aquatic snake. They are a small snake growing to 1 m at the most, but most adults range from 50 - 75 cm. They are grey to olive-brown or black in colour, with an indistinct banded pattern. The belly is usually cream with narrow dark bands highlighting the edges of each broad ventral scale. The keelback's name comes from its distinguishing feature of strongly keeled scales (rather than being smooth, the scales have a ridge down the centre making them rough to the touch). The scales are in 15 rows at the mid-body. Keelbacks are harmless, but look very similar to venemous rough-scaled snakes.
Habitat and distribution
Keelbacks prefer damp areas and are most commonly found near freshwater such as dams, creeks and swamps. They also live in gum forests and innner city suburban creeks where they have managed to be resilient to human disturbance.
Keelbacks are found in northern and eastern Queensland, Western Australia and north-east New South Wales.
Life history and behaviour
The keeback is active during the day (diurnal) and the night (nocturnal) depending on the temperature. It uses its keeled scales to grip onto slippery surfaces when travelling over mud or vegetation. When it stops moving, the keelback hides under plants, timber or in empty burrows. Keelbacks are harmless, however, they can easily be confused with a highly venomous snake called the rough-scaled snake Tropidechis carinatus.
Keelbacks only feed on vertebrates, such as frogs, tadpoles and lizards. They use their sharp backward curved teeth to seize their prey. Unlike other snakes who eat their prey head first, keelbacks consume their prey from the rear. They have a limited immunity to toad toxins and can successfully prey on small to medium sized cane toads.
The keelback is an egg layer and produces clutches of up to 18 eggs.
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