blue tongue Lizard

Introduction

Blue-tongued lizards are the largest members of the skink family. Skink lizards have overlapping scales that are usually smooth and contain small plates of bone.

Identification

The Eastern Blue-tongue is silvery-grey with broad dark brown or blackish bands across the back and tail. Individuals on the coast usually have a black stripe between the eye and the ear which may extend along the side of the neck. The Blotched Blue-tongue is dark chocolate brown to black with large pink, cream or yellow blotches on the back, and a tail banded in the same colours.

The Eastern Blue-tongue can grow to almost 600 mm in total length, of which about 360 mm is head and body.

Feeding and diet

Blue-tongues eat a wide variety of both plants and animals. Blue-tongues are not very agile and the animals they eat are mostly slow-moving. Their teeth are large and they have strong jaw muscles so they can crush snail shells and beetles.

Other behaviours and adaptations

When threatened, blue-tongues turn towards the threat, open their mouth wide and stick out their broad blue tongue that contrasts vividly with the pink mouth. This display, together with the large size of the head, may frighten off predators. If the threat does not go away, blue-tongues may hiss and flatten out the body, making themselves look bigger. A frightened blue-tongue may bite if it is picked up.

If handled roughly by their tail, Eastern Blue-tongues, particularly young ones, may drop the tail. The tail stump rapidly heals and a shorter regenerated tail grows back after a while.

Life history cycle

Female blue-tongues give birth three to five months after mating, between December and April. The Eastern Blue-tongue usually gives birth between December and January. The Eastern Blue-tongue is able to breed every year if it has sufficient food but other species of blue-tongue may often skip a year.

The embryos develop in the female's oviduct with the help of a placenta, which is as well-developed as that of many mammals. At birth, the young eat the placental membranes, and within a few days shed their skin for the first time. The young are ready to look after themselves straight after birth, and disperse within a few days.

Of all the blue-tongues, the Eastern Blue-tongue has the largest litters and the smallest young; up to 19 (but usually about 10) young are born, each measuring 130-140 mm in total length and weighing 10-20 g.

Eastern Blue-tongues probably become adults at about three years of age when they have a total length of about 400 mm. Blue-tongues are long-lived. Several captive animals have lived for 20 years, and they may live much longer.

Breeding behaviours

Blue-tongues live alone for most of the year, but between September and November males pursue females and mating occurs. At this time, males may fight aggressively among themselves. Mating may be rough, with females carrying scrape marks from the male's teeth.

Conservation status

Unfortunately, blue-tongues will eat snails and slugs poisoned by snail baits and can be poisoned themselves. Care should be taken in using snail baits and insecticides when blue-tongues are living in a garden. Blue-tongues can squeeze through small holes in and under fences, and garden pests can also cross fences, so chemicals used by neighbours can also affect your blue-tongue.

Look out for blue-tongues when mowing long grass! They will try to escape the lawn mower by hiding in the grass rather than running away. Blue-tongues like to bask on warm surfaces, and black tar roads which warm up quickly in the sun "lure" many to their deaths.

Economic impacts

Adult blue-tongues adapt well to suburbs where there are large backyards with plenty of shelter. They rapidly become used to human activity, and may live in the same place for many years. Rockeries, horizontal pipes and the cavities under houses are favourite hiding places; sunny paths and lawns provide basking sites. Plenty of food such as snails, slugs and caterpillars is usually available in gardens, and a blue-tongue in the garden will help to keep down the number of snails and plant-eating insects.

Predators

Reptile ticks are commonly found on blue-tongues; they attach under the scales and in the ear canal. They do not normally attach to mammals, and are not known to cause paralysis. A number of nematode worms parasitise blue-tongues, and may sometimes be seen in faecal pellets. Again, these worms normally only parasitise reptiles.

In the bush the major predators of blue-tongues are large predatory birds (such as Brown Falcons and Laughing Kookaburras) and large snakes (including the Eastern Brown Snake, Red-bellied Black Snake and Mulga Snake). Feral cats and dogs also eat blue-tongues.

Young blue-tongues are easy prey for suburban dogs and cats, as well as predatory birds like kookaburras. Most young blue-tongues in suburban gardens probably do not reach adulthood. A few adult blue-tongues are also killed by large dogs, although the thick bony scales of the adults protect them from many animal bites.

Danger to humans

A bite from an adult blue-tongue can cause pain, break the skin and leave a bruise but there is no venom and hence no long-term ill effect. However the bite site should be cleaned with a mild disinfectant, as with any animal bite.

snakes

Eastern brown snake

Also known as: common brown snake
Found: throughout the eastern half of mainland Australia Fast-moving, aggressive and known for their bad temper, eastern brown snakes, together with other browns are responsible for more deaths every year in Australia than any other group of snakes. Not only is their venom ranked as the second most toxic of any land snake in the world (based on tests on mice), they thrive in populated areas, particularly on farms in rural areas with mice.

If disturbed, the eastern brown raises its body off the ground, winding into an ‘S’ shape, mouth gaping open and ready to strike. Its venom causes progressive paralysis and stops the blood from clotting, which may take many doses of antivenom to reverse. Victims may collapse within a few minutes.

Western brown snake

Also known as: gwardar
Found: widespread over most of mainland Australia – absent only from the wetter fringes of eastern Australia and south-western Western Australia

Said to be less aggressive than its eastern cousin, the western brown snake is still highly dangerous and part of the group of snakes that causes the most fatalities in Australia.Western browns tend to be fast moving and nervous in temperament. When disturbed, they will run for cover, striking quickly if cornered, then making a quick getaway.

Though their venom is not as toxic as the eastern brown’s, they deliver three times as much. Bites are usually painless and difficult to see due to the small fang marks. Victims will experience headache, nausea, abdominal pain, severe coagulopathy (blood clotting disorder) and sometimes kidney damage.

Mainland tiger snake

Also known as: common tiger snake
Found: along the south-eastern coast of Australia, from New South Wales and Victoria to Tasmania and the far corner of South Australia

Mainland tiger snakes are responsible for the second-highest number of bites in Australia, as they inhabit highly populated areas along the east coast, including some metropolitan areas of Melbourne. They are attracted to farms and outer suburban houses, where they hunt mice nocturnally and can easily be trodden on by unsuspecting victims in the darkness.

Bites are fatal if untreated, causing pain in the feet and neck, tingling, numbness and sweating, followed by breathing difficulties and paralysis. The venom also damages the blood and muscles, leading to renal failure.

Adult snakes are usually (but not always) banded, with ragged stripes varying in colour from pale yellow to black along a solid, muscular body that can grow to 2m. When threatened, they flatten their necks and strike low to the ground.

Inland taipan

Also known as: fierce snake or small-scaled snake
Found: in cracks and crevices in dry rocky plains where the Queensland, South Australia, New South Wales and Northern Territory borders converge

Reclusive and rare, the inland taipan hides out in its remote, rocky habitat. This snake only makes the top 10 because of its highly toxic venom, considered to be the most potent of any land snake in the world; it has the potential to kill an adult human within 45 minutes.

Hunting in the confined space of the burrows of the long-haired rat, the inland taipan uses its potent venom to finish off prey quickly, injecting more than 40,000 times the amount needed to kill a 200g rat. The prey has little chance of fighting back.

Only a handful of people (all snake handlers) have been bitten by this species. Each survived with first aid and hospitalisation.

Coastal taipan

Also known as: eastern taipanFound: in an arc along the east coast from northern New South Wales to Brisbane and northern Western Australia. They are fond of sugarcane fields.

Coastal taipans are equipped with the longest fangs of any Australian snake (13mm), and have the third most toxic venom of any land snakes.

Extremely nervous and alert, they put up a ferocious defence when surprised or cornered, ‘freezing’ before hurling their lightweight body forward to inflict several lightning-fast snapping bites. However, they’re not usually confrontational and would much rather escape any threat.

Before the introduction of a specialised antivenom in 1956, taipan bites were nearly always fatal and caused many human deaths. The venom affects the nervous system and the blood, with nausea, convulsions, internal bleeding, destruction of the muscles and kidney damage. In severe cases, death can occur in just 30 minutes.

Mulga snake

Also known as: king brown snake
Found: throughout Australia, except in Victoria, Tasmania and the most southern parts of Western Australia – the widest distribution of any Australian snake

The mulga is the heaviest venomous snake in Australia and has the largest-recorded venom output of any in the world – delivering 150mg in one bite; the average tiger snake only produces 10-40mg when milked.

Their temperament seems to vary with locality. Southern mulgas are reported to be shy and quiet, whereas northern specimens are much more agitated if disturbed – when they throw their heads from side to side and hiss loudly. Mulgas bite savagely, even hanging on and chewing as they inject massive amounts of highly toxic venom, which destroys blood cells and affects the muscles and nerves. Though commonly known as a king brown snake, the mulga is actually a member of the black snake genus Pseudechis, and black snake antivenom is needed to treat a bite.

Lowlands copperhead

Also known as: common copperhead
Found: in relatively cool and cold climates in south-eastern Australia, southern Victoria, Tasmania and the islands of Bass Strait

The lowlands copperhead is the only venomous snake found above the snow line, active in weather usually considered too cold for snakes. A water lover, copperheads snakes are at home around dams, soaks, canals, drainage ditches and along the verges of roads.

Copperheads are shy and prefer to avoid humans, though they live in populated and agricultural areas. If cornered, they will hiss loudly, flatten their body and flick or thrash about, usually without biting. With further provocation they may lash out, though they are slow to strike and can be inaccurate.

Copperhead venom is neurotoxic (damaging nerves), ruptures the blood cells and damages the cells and muscles – but rarely causes fatalities.

Small-eyed snake

Also known as: eastern small-eyed snake
Found: widely distributed along the east coast, from Victoria to Cape York

At about 50cm long, the small-eyed snake may be petite but its venom can pack a punch and shouldn’t be underestimated. Little is known of its toxicity, but bites have caused illnesses in snake handlers and there has been one known fatality. The venom contains a long-acting myotoxin that continues to attack muscle tissue (including the heart muscle) for days after the bite.

Though common, small-eyed snakes are secretive night-dwellers and therefore don’t often come into contact with humans. Coloured black or dark grey with a silvery belly, they blend into the night. When disturbed they may thrash about aggressively, but are not usually inclined to bite.

Common death adder

Also known as: southern death adder
Found: in eastern Australia (except the far north and south), southern South Australia and Western Australia

The common death adder is an ambush predator that sits motionless, concealed in leaf litter, sand or gravel, twitching the worm-like lure on the end of its tail to attract prey.

Unlike other snakes that flee from approaching humans crashing through the undergrowth, common death adders are more likely to sit tight and risk being stepped on, making them more dangerous to the unwary bushwalker. They are said to be reluctant to bite unless actually touched.

About half of death adder bites proved fatal before the introduction of antivenom. The venom contains a type of neurotoxin which causes loss of motor and sensory function, including respiration, resulting in paralysis and death.

Red-bellied black snake

Also known as: common black snake
Found: distributed down the east coast (though not to Tasmania) and slightly into south-eastern South Australia

The red-bellied black snake is somewhat less venomous than many other Australian snakes, but you’re more likely to come across it in urban areas and its bite is certainly no picnic, causing significant illness and requiring medical attention.

Red-bellied blacks are one of the few large venomous snakes still found in the Sydney region, and at 2m-long are capable of eating other snakes. They are not particularly aggressive and will escape from humans if possible, but when threatened will flatten their bodies and hiss loudly.

The venom causes blood-clotting disorder and muscle and nerve damage, enough to knock you off your feet, but rarely deadly. No deaths have been confirmed from bites by this species.

What Are Deserts

Deserts cover about a fifth of the Earth's surface. Deserts have extreme environments. Deserts get between 1 and 15 inches of precipitation per year. Desert plants and animals have special adaptations that help them survive in this extreme environment. Most people think of deserts as being hot and dry, but some deserts are actually cold! There are four types of deserts: subtropical deserts are hot and dry year-round; coastal deserts have cool winters and warm summers; cold winter deserts have long, dry summers and low rainfall in the winter; polar deserts are cold year-round.

Coastal Deserts

Coastal deserts occur in cool to warm areas along the coast. They have cool winters and long, warm summers. Coastal deserts are located on the west coasts of continents between 20° to 30° latitude. Winds off the coast blows in an easterly pattern and prevents the moisture from moving onto the land. The Namib Desert in Africa and the Atacama Desert in Chile are coastal deserts.

Subtropical Deserts

Subtropical deserts the hottest deserts. They are found in Asia, Australia, Africa and North and South America. In the United States, the Chihuahuan, Sonoran and Mojave are all subtropical deserts. Subtropical deserts are very hot and dry in the summer and cooler but still dry in the winter. Rainfall happens in short bursts. The air is so hot and dry in these deserts that sometimes rain evaporates before it even has a chance to hit the ground! The soil in subtropical deserts is usually either sandy or coarse and rocky.

Cold Winter Deserts

Cold winter deserts are also known as semi-arid deserts. They have long, dry summers and cold winters with low rain or snowfall. In the United States, the Great Basin, the Colorado Plateau and the Red Desert are all cold winter deserts. Other cold winter deserts include the Gobi desert in China and Mongolia and the Patagonian desert in Argentina. The lack of rainfall in cold winter deserts is often caused by the rainshadow effect. The rainshadow effect happens when a high mountain range stops moisture from reaching an area. The Himalayan Mountains prevent rainfall from reaching the Gobi Desert.

Polar Deserts

Plants and animals in subtropical deserts must be able to withstand the hot temperatures and lack of moisture. Shrubs and small trees in the subtropical desert usually have leaves adapted to retain moisture. Animals in subtropical deserts are usually active at night, when it is cooler
Polar desert are found in the Arctic and Antarctic regions. Like warmer deserts, they also get very little precipitation.