Thorny devils, also known as thorny dragons, thorny lizards and molochs, are small lizards covered from head to tail with spines and thorns. They inhabit the deserts of Australia, living in sand, spinifex grasslands and scrub. There are no other lizards like thorny devils anywhere on the planet.
Thorny devils are only about the size of a mouse. They have an extremely spiky looking appearance, with a rigid body structure. Thorny devils have false heads on the back of their necks that confuse predators when they dip their real heads down. Between the cone shaped spikes of thorny devils, small channels collect water from all parts of their body to be transported to their mouths.
Female thorny devils are usually slightly larger than male thorny devils. Females are paler in color; males being slightly redder. Both male and female thorny devils change colors. In the morning when it is cool, thorny devils are a drab olive-brown color. During the day when it gets warmer, they turn yellow and red. Their changing skin coloration helps thorny devils to blend into the Australian desert throughout the day. At night, thorny devils dig themselves into the soil to keep warm. When the heat is extreme during the day, they dig underground burrows.
Thorny devils walk slowly, stop frequently, and rock back and forth. Their shaky, jerky movements and frequent freezing in place helps them conceal themselves from predators.
Thorny devils are obligate myrmecophages, feeding primarily on ants. They eat thousands of black ants every day. They receive most of their water from moisture that forms as dew drops each night. While thorny devils are often seen standing in water, they do not drink it. Their bodies are able to simply absorb it and store it for later use. When it is very hot, thorny devils can excrete salt to retain their water.
Thorny devils are “sit-and-wait” predators. They sit near ant trails and wait for the ants, then use their sticky tongues to capture the ants. Their teeth are well designed to handle the hard, chitinous bodies of ants. The mandibular teeth of thorny devils fit between maxillary teeth to create efficient shearing tools.
Thorny devils do not randomly scatter their fecal pellets. They place them in latrine sites.
Thorny devils are almost completely inactive during the hottest summer months and the coldest winter months. During these times they take refuge underground. They are most active in the autumn and late winter months.
During mating season, thorny devils build underground nests for their eggs. Males are aggressive with each other during mating season. Females give off an intoxicating scent to attract males. After mating, males go off in search of other females. Mother thorny devils lay ten eggs in their burrow during the spring-summer season (September-December). When the eggs hatch in three to four months, thorny devil babies are immediately able to take care of themselves.
Thorny devils are preyed upon by bustards, foxes, bobcats, coyotes, goannas, falcons and snakes. Goannas also prey on the eggs of thorny devils. Thorny devils puff themselves up to appear larger when confronted by predators. Their densely-packed spikes also make predators think twice before attacking them.
Thorny devils can live up to 20 years in the wild.
THREATS TO THORNY DEVILS
Thorny devils are threatened by habitat loss and changes in climate. They are often hit by cars. Their populations are declining.
Thorny devils are also victims of the pet trade, inhumanely kept in confinement for humane entertainment. They are difficult to maintain in captivity and rarely survive longer than a few months.