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The lace monitor, or tree goanna, is Australia's second-largest lizard and one of the largest lizards on Earth. The Australia Zoo has two remarkable lace monitors: an 8-year-old male named Smiley and a 10-year-old male named Sebastian.

Smiley and Sebastian are very shy and quiet, but thoroughly enjoy feeding time. Smiley is quite clever at sitting up in his palm tree and catching food that the keepers toss to him.

Lace monitors are found in a variety of wooded habitats along the east coast of Australia, including rainforest and dry woodland. They are true generalists, adept at running, swimming, burrowing and scaling trees with their powerful limbs and long, strongly curved claws.

In captivity, lace monitors like Smiley and Sebastian usually feed on mice, rats and chopped-up rabbit or poultry. In the wild they eat insects, other reptiles, birds and their eggs, small mammals, fish — essentially any small animal that they can overpower. They also feed opportunistically on carrion.

During the nesting season, lace monitors attack birds' nests with a vengeance, feeding on the eggs and chicks of many a ground- or tree-nesting bird. They are thought to feed on birds to a greater extent than any other monitor lizard.

When threatened they will usually seek shelter in the nearest tree, hiding on the opposite side of the trunk. If cornered however, a lace monitor will bite and lash out with its muscular, compressed tail.

Mating occurs during the summer, when up to six males will court a single female, the largest usually winning the right to reproduce.

Expectant mothers generally lay their eggs in termite mounds, which they break into with their powerful claws. When the termites repair the nest, the eggs are entombed in a controlled environment, safe from predators.

At the start of the rainy season, when the soil softens, the eggs hatch. Females will sometimes even return to help the young dig their way out.