AUSTRALIAN WATER DRAGON

The Australian water dragon (Intellagama lesueurii), which includes the eastern water dragon (Intellagama lesueurii lesueurii) and the Gippsland water dragon (Intellagama lesueurii howittii) subspecies, is an arboreal agamid species native to eastern Australia from Victoria northwards to Queensland. There may be a small introduced population on the south-east coast of South Australia.

The Gippsland water dragon is generally the more southern of the two subspecies and the more cold adapted and heat sensitive. Visually distinguishing the Gippsland water dragon from the Eastern water dragon is relatively easy, as long as their skin is reasonably clean and not stained from the water, as identification of the two subspecies depends largely on observable differences in colours and patterns.

Australian water dragons have long powerful limbs and claws for climbing, a long muscular laterally-compressed tail for swimming, and prominent nuchal and vertebral crests (a nuchal crest is a central row of spikes at the base of the head. These spikes continue down the spine, getting smaller as they reach the base of the tail).

Including their tails, which comprise about two-thirds of their total length, adult females grow to about 60 cm long, and adult males can grow slightly longer than one metre and weigh about 1 kg. Males show bolder colouration and have larger heads than females. Colour is less distinct in juveniles.

The Australian water dragon's diet depends on its size. Juveniles and yearlings tend to feed on spiders and small insects such as ants, crickets, and caterpillars. When they get bigger, so does their prey. An adult diet includes small rodents, such as baby mice, other reptiles, frogs, fish, crabs, yabbies, molluscs, worms and eggs, although insects are still the most commonly consumed. Types of vegetation reportedly consumed include figs, lilly-pilly fruits, berries, and other fruits and flowers.

This post is part of the Saturday Critters meme

WATER DRAGON

Male Eastern Water Dragon, (Intellagama lesueurii). Australian water dragons have long powerful limbs and claws for climbing, a long muscular laterally-compressed tail for swimming, and prominent nuchal and vertebral crests (a nuchal crest is a central row of spikes at the base of the head). These spikes continue down the spine, getting smaller as they reach the base of the tail.

Including their tails, which comprise about two-thirds of their total length, adult females grow to about 60 cm long, and adult males can grow slightly longer than one metre and weigh about 1 kg. Males show bolder colouration and have larger heads than females. Colour is less distinct in juveniles.

Australian water dragons are extremely shy in the wild, but readily adapt to continual human presence in suburban parks and gardens. They are fast runners and strong climbers. When faced with a potential predator, they seek cover in thick vegetation, or drop from an overhanging branch into water. They are able to swim totally submerged, and rest on the bottom of shallow creeks or lakes for up to 90 minutes, to avoid detection.

Both males and females display typical agamid behaviour such as basking, arm-waving and head-bobbing. Fast arm-waving signals dominance, while slow arm-waving signals submission. Males are territorial, and in areas of higher population density, males exhibit displays of aggression toward other males including posturing, chasing and fighting.

This post is part of the Saturday Critters meme

GECKOS

Geckos are lizards belonging to the infraorder Gekkota, found in warm climates throughout the world. They range from 1.6 to 60 cm. Most geckos cannot blink, but they often lick their eyes to keep them clean and moist. They have a fixed lens within each iris that enlarges in darkness to let in more light.

Geckos are unique among lizards in their vocalisations. They use chirping sounds in social interactions with other geckos. They are the most species-rich group of lizards, with about 1,500 different species worldwide. The New Latin gekko and English "gecko" stem from the Indonesian-Malay gēkoq, which is imitative of the sound the animals make.

Many species are well known for their specialised toe pads that enable them to climb smooth and vertical surfaces, and even cross indoor ceilings with ease. Geckos are well-known to people who live in warm regions of the world, where several species of geckos make their home inside human habitations. These (for example the house gecko) become part of the indoor menagerie and are often welcomed, as they feed on insects, including mosquitoes. Unlike most lizards, geckos are usually nocturnal.

This post is part of the Saturday Critters meme.

SNAKE SEASON!

Australia has nearly 200 known species of snake, only 25 of which are considered potentially deadly. Common snakes in the Melbourne area and surrounding suburbs include the Tiger Snake, Eastern Brown Snake, Copperhead Snake, White-Lipped Snake, Small-Eyed Snake and Red-Bellied Black Snake. There are over 27 types of snake in Victoria and a number of these are venomous, including the tiger snake, the copperhead, the brown snake and the red-bellied black snake.

Darebin Parklands is a nature reserve in the midst of inner suburban Melbourne. It has a host of animal species, many of them native that live happily in its confines. These creatures of course include snakes. Numerous signs relating to snakes are found throughout the Parklands, reminding people to take care during the Summer between the months of October to April.

I have seen snakes a number of times, in the Parklands and elsewhere, but fortunately these encounters have been innocent enough. While seeing a snake may be an intimidating experience, they are typically shy creatures and most will try to avoid confrontation with humans and quickly slither away (how quickly they can move is indeed a sobering experience).

The latest encounter was with a 1.2 m tiger snake that was crawling along the path, rushing to get to an area well-covered with grass and bushes. The day was very hot and the snake moved extremely quickly, rushing away from me towards cover. It was fortunate I had the camera in my hands and was able to take a few photos.

Tiger snakes are a highly venomous snake species found in the southern regions of Australia, including its coastal islands, such as Tasmania. These snakes are highly variable in their colour, often banded like those on a tiger, and forms in their regional occurrences. All populations are in the genus Notechis, and their diverse characters have been described in further subdivisions of this group; they are sometimes described as distinct species and/or subspecies.

Tiger snakes accounted for 17% of identified snakebite victims in Australia between 2005 and 2015, with four deaths recorded from 119 confirmed envenomations. Tiger snake venoms possess potent neurotoxins, coagulants, haemolysins, and myotoxins. Symptoms of a bite include localised pain in the foot and neck region, tingling, numbness, and sweating, followed by a fairly rapid onset of breathing difficulties and paralysis. In a study, the mortality rate from untreated bites is reported to be between 40 and 60%.

The risk of being bitten by a snake or dying from a snake bite is extremely low. While highly variable, it is estimated that no more than 100 or 200 people each year get bitten by snakes in Victoria. Despite this, on average only one person every 5 years dies of a snake bite. The last recorded fatal snake bite in Victoria was by a tiger snake in November 2014. To put the risk of dying from a snake bite in perspective, consider that each year in Victoria about 40 people die from drowning in waterways and about 250 people die in car accidents.

Treatment is the same for all Australian venomous snakes. The pressure immobilisation method is used to inhibit the flow of venom through the lymphatic system. Broad, thick bandages are applied over the bite, then down and back along the limb to the armpit or groin. The affected limb is then immobilised with a splint. Identification of the venom is possible if traces are left near the wound.

The availability of antivenom has greatly reduced the incidence of fatal tiger snake bites. Among the number of deaths caused by snakebite in Australia, those from tiger snakes are exceeded only by the brown snake. In most Australian states, tiger snakes are protected species, and to kill or injure one incurs a fine up to $7,500, as well as a jail sentence of 18 months in some states. It is also illegal to export a native Australian snake.

This post is part of the Saturday Critters meme,

and also part of the Camera Critters meme.