Giant Lizard

Check out this awesome picture that I took of a lizard in the Sydney Blue Mountains. The resemblance to a crocodile is quite interesting. Click the picture to enlarge.

A Look into Animal Gigantism

The Komodo dragon is the largest living species of lizard. They grow to more than 3 metres long and can weigh up to 165 kilograms. The dragon has a forked tongue that is 40 centimetres long.

These flightless "dragons" are effective predators and have enough speed and strength to take down deer, wild pigs and water buffaloes. They don't need to capture live prey directly, since they have a venomous bite that severely decreases blood clotting. Their saliva contains bacteria that can kill wounded victims in a few days.

Komodo Dragons can live for 50 years. They display relatively tame behaviour within a short period of time in captivity and are also capable of recognising individual humans.

Their unusual size is attributed to "island gigantism", where the size of animals isolated on an island increases dramatically in comparison to their mainland relatives. The explanation for this is that large mammalian carnivores are often absent on islands, due to their large range requirements and/or difficulties in over-water dispersal.

In their absence, the ecological niches for large predators may be occupied by birds, or reptiles in this case, which can then grow to larger-than-normal size.

As such, these giant animals are closely related to their smaller counterparts. With the arrival of humans, many giant island endemics have become extinct.

Some other examples of island gigantism include giant rats, giant ducks, giant rabbits, dodos (closely related to pigeons and doves), giant tortoises, Haast's Eagle (largest known eagle which attacks at speeds of 80 km/h), elephant birds (largest known bird, growing up to 2.7 metres tall and weighing about 450 kg) and King Kong. (Okay, you got me, the last one was fictional.)

The cousin of island gigantism is the better known "island dwarfism". But who likes things that are tiny?

Another natural phenomenon is "deep sea gigantism", where deep-sea-dwelling animals to display a larger size than their shallow-water counterparts. This is probably due to better nutrients in the deeper water.

Examples include Japanese spider crabs (up to 3.7 metres across from the tip of one outstretched claw to another and weighing 18 kg), the seven-arm octopus (largest octopus, 4 metres long and 75 kg), giant oarfish (world's longest bony fish, reaching up to 12 metres long and weighing 270 kg), the colossal squid (larger than the giant squid, largest known invertebrate, 12-14m in length, weighs up to 495 kg).

Bibliography

Huey, Raymond B. "Komodo dragon." World Book Student. World Book, 2010. Web. 16 Jan. 2010.

Clarke, Simon James. "Elephant bird." World Book Student. World Book, 2010. Web. 16 Jan. 2010.

"Komodo dragon." Encyclopædia Britannica. Encyclopædia Britannica Online School Edition. Encyclopædia Britannica,
2010. Web. 16 Jan. 2010.

"Aepyornis (Elephant Bird)." Encyclopædia Britannica. Encyclopædia Britannica Online School Edition. Encyclopædia Britannica,
2010. Web. 16 Jan. 2010.

http://en.wikipedia.org/wiki/Komodo_dragon
http://en.wikipedia.org/wiki/Island_gigantism
http://en.wikipedia.org/wiki/Deep-sea_gigantism