Water Python

The Water Python is a northern Australian species that, as its name suggests, is usually associated  ith water. It is found around freshwater billabongs,watercourses, lagoons and swamps and feeds on mammals, birds, particularly waterbirds, and reptiles. It is also known to eat birds’ eggs. The Water Pythons around Fogg Dam near Darwin have been found to occur in huge numbers.

Their biology is tied in to that of the water rat ,which is also abundant there. The only food in  sufficient quantity for newly hatched Water Pythons to eat are baby water rats. If the rats fail to breed or breed too early, then only very few baby pythons will survive from that year.

How do snakes swallow large prey?

Small snakes tend to eat small prey such as lizards, which do not present the with any problem. Large snakes however, find it more efficient to take large prey and they must have a way of eating and digesting them.

To achieve this they are able to drop their lower jaw at the back as well as the front. The lower jaw also stretches sideways as it is joined at the front by a very elastic muscle.  This means not only can it stretch its mouth wider horizontally but it can also work one side of its jaw forward independently of the other side.

The snake can literally 'walk' its mouth over over the pray using its teeth to anchor and pull forward. Also, a snakes skin is very flexible, allowing i to eat animals that have a larger diameter than itself.

There are other adaptations to help snakes eat large prey. Firstly,

• Their brain in encased in bone; this protects it from any kicks of its prey while struggling to escape.  
• Snakes have a tube in the throat called the 'Glottis'; which is able to protect forward beyond the lower jaw so the snake can breathe while eating, 

The advantage of being able to eat large food items is that you do not have to eat as often. Snakes can go for many months without eating and it is probable that large snakes eat only a few meals during a year. It is more efficient to catch and eat larger prey rather than spending lots of energy chasing smaller animals.

How do snakes eat and digest food?

All snakes are carnivorous; meaning that they eat other animals. They do not eat vegetable matter and generally they catch and eat living prey, although instances have been recorded of snakes eating road-killed animals.

Because most cannot dismember their food they must eat it whole, so the select prey that can be swallowed easily or they have adaptations to cope with large prey. In some species the oung and adults eat the same but different sized prey.

In other species, there is a shift as the snake grows. For example, hatching carpet pythons eat small skinks but the adults eat rabbit, rats, possums bandicoots and even wallabies.

Digesting their food

This is where venomous snakes have an advantage over the non-venomous ones because the venom they have helps break down the tissue of the prey and also speeds up digestion. Whether venomous or not, snakes still have to keep their body temperature up to aid digestion.

If they are too cool, digestion is slowed down and there is a possibility that the prey will rot in the snakes stomach and kill it. That is why when a snake has eaten large prey it will often bask in the sun for extended periods.

How do snakes move?

With up to 400 vertebrae, snakes have remarkable flexibility and some can travel at up to 10 kph. There are four different ways in which they may move.

The usual method is an Undulating movement in which the snake uses irregularities on the ground to get leverage and push it's body against. Done at a number of points along the body at the same time, this creates a constant undulating flow. Brown snakes and whip-snakes move like this.

Then there is the slow Straight-line way of moving used by large and bulky snakes such as Pythons. The head and fore-body are stretched straight forward. The belly scales then gain a hold and the snake advances by contacting its body muscles and dragging the rest of itself forward.

In the Concertina method sometimes adopted by Brown-tree-snakes, the snake forms a series of body loops and then pushes its head and fore-body forward. Having obtained a purchase, it draws the body loops forward and the process is repeated.

Sidewinding is a means of locomotion used in soft sand or mud whereby a snake moves diagonally along a surface. The White-bellied Mangrove snake, for example, sometimes moves by sidewinding. It pushes its head and neck against a surface and flicks its body forward in a loop. Once the tail and back part of the body gain a grip, it flicks it's body forward in a loop again.

Which snakes are venomous?

There are three venomous snake families in Australia;

• Elapids
• Sea Snakes
• Sea Kraits 

All the Elapid snakes are venomous, although most are only mildly so ans are not considered to be dangerous. They all have fixed hollow fangs in the front of the upper jaw, connected on each side by a duct to the venom gland. There are 15-23 scale rows around the mid body, excluding the broad belly scales.

The completely aquatic Sea Snakes have vertically compressed paddle-shaped tails and nostrils which are situated on the top of the snout with flaps that close when the snake is submerged. The vast majority of sea snakes are very venomous are rarely encountered.

While essentially marine snakes, the Sea Kraits do com onto land, particularly to lay eggs. All are characterised by numerous black cross-band and laterally placed nostrils. Although very poisonous sea kraits are reluctant to bite and are also rarely encountered.

Are reptiles cold blooded?

Reptiles are often refereed to as 'Cold blooded' animals, which is an over simplification of a complex arrangement. Reptiles are Ectotherms, this means that they rely on external heat sources to maintain a constant body temperature. Because they have no internal mechanisms to generate heat, they must seek out warmth .

Reptiles are therefore most numerous in tropical or hot and arid areas where the air temperature is high as they do not want to spend a lot of time warming up.

As they do not maintain a high body heat, they require far less food than mammals or birds of a similar size and so the have been able to successfully colonise areas that cannot sustain high numbers of birds and mammals.

How long do reptiles live?

Not very much is known about the longevity of most reptile species in the wild but there is plenty of information on reptiles kept in captivity. Certainly Blue-tongue, Water-dragon and other similarly sized lizards have been kept in captivity for 20 to 30 years.
The smaller species are not so long lived, but some Geckos have been reported to live in captivity for around 10 years.

Snakes are remarkably long lived in captivity ans some have been kept up to 20 years. In the wild they are unlikely to live as long. A less assured food supply, greater risk of predation and other hazards would reduce their life expectancy significantly. Some species are known to only live for one or two years in the wild.

A curious feature of reptiles is that no matter how long they live, they continually replace their teeth. This is in contrast to mammals, which lose their teeth when they get old.

Why do reptiles have scaly skin?

Most people know that snakes and lizards are reptiles. Turtles and Crocodiles are also reptiles but frogs (which are amphibians) are not. Reptiles are vertebrates that breath air and depend on outside sources for body heat.

The most obvious feature of reptiles is their non-porous, scaly skin. This helps to greatly reduce water loss from the body; as a result they do not need constant access to water.

Some reptiles get all their liquid requirements from the prey they eat. This ability of reptiles to conserve body fluids means that they are able to successful y inhabit very dry and arid parts of Australia.