Earless monitor lizard
The earless monitor lizard, Lanthanotus ocellatus, is a species of lizards found in South Africa. They are considered one of the most primitive members of the monitor family.
They live in arid regions where there is little vegetation. Their diet consists mostly of insects such as beetles, grasshoppers, crickets, moths, butterflies, flies, ants, spiders, centipedes, millipedes, scorpions and earthworms. They eat about 10% of their body weight each day.
In addition to eating, their main source of water intake is through drinking. They drink up to three times a week depending on how hot it is outside. When temperatures reach over 50 degrees Celsius, they will stop drinking altogether.
Their eyesight is very poor. They use smell and hearing to find food and mates. They can hear sounds up to 20 meters away and can see objects up to 5 meters away.
A study published in 2013 showed that the earless monitor lizard uses sound waves to communicate with others. This discovery could help scientists better understand the evolution of communication among animals.
The earless monitor lizard was first described in 1878 by Austrian zoologist Franz Steindachner, who named it Varanus exanthematicus. In 1880, Steindachner coined the name Varanus exanthematica, meaning “earless monitor”. The species was later moved into the genus Varanus. In 1896, French naturalist Henri Émile Sauvageau proposed changing the specific epithet to exanthematicus, because he felt the word exanthematicum (“having many small scales”) better fit the animal’s appearance. This proposal was accepted by the International Commission on Zoological Nomenclature, and Varanus exanthematicus became the standard scientific name for the earless monitor lizard.
In 1881, German herpetologists Wilhelm Peters and Eduard von Martens published a description of a second species, Varanus gabonensis, based on specimens collected near Lake Tumburu in Gabon. They thought the species was distinct enough to warrant recognition as a separate taxon, and assigned it the rank of subspecies under V. exanthematicus. However, subsequent authors disagreed, arguing that the differences between the two forms were too subtle to justify treating them as different species. Consequently, the synonymy of V. exanthematicos and V. gabonensis remained unresolved until recently.
In 2016, researchers used mitochondrial DNA sequencing to show that the two species are closely related, and that the earless monitor lizard belongs in the same genus as the common monitor lizard, Varanus varius. The study concluded that the two species had diverged about 2 million years ago, long before the formation of the Congo Basin.
The earless monitor lizards‘ closest living relatives are the Komodo dragon and the Philippine crocodile.
Range and habitat
The species is named for its lack of external ears, which distinguishes it from similar lizards such as the Komodo dragon. This feature is shared with some skinks, geckos, and amphisbaenids. Its closest relative is the banded earless monitor (Varanus exanthematicus), which is also found in southeast Asia.Earless monitor lizards are medium-sized, slender, lizard-like reptiles found throughout Australia. They grow up to 30 cm (12 inches) in length, with males typically being larger than females. Their bodies are cylindrical, with a head, tail, four pairs of legs, and a pair of wings. They are covered in overlapping plates of skin, each scale having a distinctive pattern, giving them a striped appearance. They possess retractable claws on their front feet, a feature shared with some snakes. They are nocturnal, spending most of their day hidden underground. However, during daylight hours, they emerge into open areas such as roadsides, where they feed on insects and spiders.
The species is named for its earless appearance; however, it does have ears, but they are located under the skin rather than visible externally. This trait distinguishes it from the related genus Pseudemoia.
Earless monitor lizards have been described as being “the most bizarre looking lizard” because of their appearance. They are characterized by having a cylindrical body with a long neck, short limbs and long sharp claws. Their head is small compared to their body size, and they have small eyes, semi-transparent lower eyelids, six longitudinal rows of strongly-keeled scales, and no external ear openings. Most species have a dark brownish-grey colouration, but some species have lighter coloured bodies and others darker ones.
The largest known specimen weighed about 2 kg (4.5 lb).
Adult earless monitor lizards are medium-sized lizards found throughout much of Southeast Asia. They typically have a snout–to–vent length (SVL; i.e., the distance from the tip of the nose to the end of the tail) of about 20 centimeters (7.9 inches), and a total length (from head to vent) of about 40 centimeters (16 inches). Their bodies are slender and elongated, and they have long tails. Earless monitors have short legs and toes, and lack hind limbs.
They are diurnal animals, spending most of their day basking in the sun, and are active during the night. They eat small invertebrates such as insects, spiders, centipedes, millipedes, grasshoppers, crickets, cockroaches, beetles, worms, mites, slugs, snails, and frogs.
Earless monitors lay eggs in burrows dug into moist soil, usually near water sources. Females give birth to live young, although there is some evidence that captive females sometimes produce stillborn offspring. Hatchlings grow rapidly, reaching sexual maturity within one year. Males reach sexual maturity at about four months old, while females reach it at around six months.
The species is considered omnivorous, meaning it eats both plants and animals. Its diet includes fruits, flowers, leaves, roots, seeds, bark, fungi, algae, mosses, lichens, tubers, bulbs, stems, shoots, nuts, berries, mushrooms, cacti, and insect larvae.
The earless monitor lizard spends most of the daylight hours hidden in underground burrows where it can avoid predators such as snakes. Its diet consists mainly of small invertebrates and insects. It is active during the night, feeding on smaller prey including crickets, grasshoppers, beetles and millipedes. It is also known to eat larger prey such as frogs, mice and rats.
Earless monitors are found throughout Australia and New Guinea, occurring in habitats ranging from rainforests to deserts. They live in areas with sparse rainfall, preferring those with sandy soils. In some places, populations are declining due to habitat loss and predation by introduced species such as cats, foxes and feral pigs.
Although generally docile and inactive, male Komodo dragons are much more aggressive than females when captured. A researcher named Paul Hochman was bitten while handling a female dragon during a research project. He experienced no ill effects, but he had a small puncture wound on the tip of his middle finger. His finger swelled up within 24 hours, and it took him three days to heal.
The Komodo Dragon is a large lizard native to Indonesia. They are closely related to the Gila Monster, and both species belong to the same genus, Varanus. The Komodo Dragon is known for being able to hold its breath underwater for over five minutes. This ability makes it quite dangerous, because it can ambush prey without warning. It is believed that the Komodo Dragon uses its long tongue to probe around its prey, detecting vibrations produced by breathing. Once the prey stops moving, the Komodo Dragon bites down and swallows its meal whole.
They are omnivorous; they will eat both plant material and animal matter. They may even eat small amounts of meat, including insects such as grasshoppers.
In captivity, they will eat food pellets and meal worms.