Earless Monitor Lizard: Water or Land Reptile.
The earless monitor lizard has been subject to endless debate about how to classify it. Some scientists think it should be thrown together with other land monitor lizards while others think it deserves its own family.
Examination of the lizard began with Mr. Tom Harrisson (again, here we must be very careful in evaluating Harrissons writings) when he kept one called Datu. He noted the lizard was very lethargic during the day but active at night. The characteristic was verified when flooding in the 1963-64 monsoon season brought forth an “unequalled” collection. Four of these rare specimens were sent to Germany.
In an earlier paper, (which I have not read) Harrisson stated when the lizard was active it neither moved quickly or far. The front legs are primarily used to steer the animal while the hind legs and body are used to push the animal along. The result is a snake like progression as the body is not lifted off the ground.
Feeding was the first problem when they were kept in captivity. Harrisson was said to have fed his lizard the yolk of sea turtle eggs. While not available in Germany and the USA where they were sent, sole (fish) (Pleuronectus) seemed to be a viable alternative. Later, earthworms were introduced into the diet and seemed to satisfy the lizard.
The lizard is termed semi-fossorial which means adapted to burrowing but also means he can live in water. The lizard seems to be at home in the water as it spends days there as it feed and mates in a aquatic environment. The lower eyelid is clear which allows the lizard to see with its eyes closed.
The earless lizard shares a unique feature with the burrowing lizards in that it has a closed external ear opening, which is a characteristic of a burrowing animal. Examination shows the ear is quite functional below the skin. The earless lizards also has a nose similar to a crocodiles. They lie straight up and slightly back and rest on a pair of raised mounds. The tail was thought to be an appendage used in climbing but now it seems to be an anchoring device in fast running streams where it is found.
The major question is “Why does it burrow?” The answer seems to be in keeping body temperatures cool in the hot tropical climate. Harrisson had his in his air conditioned bedroom while it seems others lived near a cool stream. Harrisson also said the animal had to have water often or it would dry out.
The biologically mixed up earless monitor lizard has been placed in its own family, Lanthannotide where resides alone. It seems to be a remnant of a group that died out long ago.
From: A Summary of Observations from the Earless Monitor by Robert G. Sparackland in the Sarawak Museum Journal December 1972.
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