The Understory


July 22, 2007


The most abundant vertebrate predators of the forest floor are reptiles, namely snakes and lizards. Best known of forest snakes are the giant constrictors, pythons of the Old World and Australasia, and boas of New World, but many of these are arboreal, aquatic, or relatively small. The majority of the snakes of the forest floor are small to medium sized, nocturnal, and mildly poisonous. They eat a range of amphibians, mammals, small birds, and insects. Very few of these species pose a threat to humans, although some are notorious for inflicting bites. The fer-de-lance viper of the New World, cobras of the Old World, and bushmaster of the New World are well-known examples.

There are several notable snakes of the rainforest with strange habits or characteristics. For example, the mole viper has long fangs that protrude beyond the corners of its mouth, while the African egg-eating snake, with its detachable jaw hinge, is specially adapted to feeding exclusively on bird eggs. This snake species is equipped with lower vertebrae that have an enamel-like coating and penetrate the esophagus to act as a saw-like structure. Although its head is about the size of a human finger, the African egg-eating snake can swallow eggs larger than that of a hen. One African snake species, sometimes labeled the "two-headed snake," has a tail that resembles its head, and a head that resembles a tail. In addition, to further confuse predators, the snake moves its tail in a manner that mimics the way most snakes move their heads. Thus if attacked, the tail (resembling the head) is the most likely target and the snake is much more likely to escape.

The Komodo dragon of folklore would seem to be one of the largest, more formidable beasts on earth. However, in reality, many of the "facts" about the Komodo dragon are exaggerated. First of all, the Komodo dragon is a lizard belonging to the group of 31 species of lizards known as monitors, found in the Old World. Secondly, the Komodo dragon does not reach 30 feet (9 m) as reported by many, but the largest recorded specimen was just over 10 feet (3 m) in length—still an impressive size. The Komodo dragon is found on a few scattered islands in Indonesia south of Celebes. With a belly full of deer, one may reach 500 pounds.

Chameleons, discussed in the canopy section are actually most active near the ground. There are some 135 species of chameleons found in Africa, half of which are endemic to Madagascar (Malagasy chameleon pictures). These solitary lizards are well adapted to their surroundings with their well- known ability to change color, along with their large eyes which can be moved independently, and their meter-long tongue. Interestingly, chameleons often do not change color to match their surroundings, but instead to convey emotions, defend territories, and communicate with mates. At the height of the breeding season, colors are spectacular, as males try to impress females. At night, in a relaxed state, chameleons turn pale, almost white.

Another group of lizards from Madagascar is the fringed, leaf-tailed, or Uroplatus geckos (pictures) which are incredible camouflage artists. Some species look exactly like bark, while others resemble moss when they flatten themselves against their surroundings. When discovered, Uroplatus geckos respond by throwing their mouths wide open, showing the bright orange-red interior, and erecting their tails.

Amazonian Reptiles - A Historical Account

Geckos are found worldwide and are quite famous for their abundance and loud call. Numerous species are kept widely as pets, while house geckos are found in virtually every house in the tropics, where they feed on house insects.

Parson's chameleon in Madagascar. Click image for more photos. Photo by Rhett A. Butler

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Continued / Next: Ground Amphibians