But the Komodo dragon is the heaviest lizard of all, with an average weight of 60kg (130lb) and a maximum of 80kg (176lb), and it is a fearsome predator. It has large, sharp, serrated teeth for cutting and tearing prey, but its hidden weapon is its bacteria-laden saliva. Once bitten, a victim may escape, but within a few days it will succumb to infection. The dragon then tracks it down with its acute sense of smell – a sense that also makes it a super-efficient scavenger.
Though it is a giant by today’s standards, the Komodo dragon may be a pygmy compared to one of its mainland ancestors (Flores Island supported other ‘pygmies’, including a now-extinct elephant, on which the dragon is believed to have preyed). In Australia there once existed a true giant, the 6.9m (23ft), 617kg (1,370lb) monster monitor Megalania prisca, which became extinct about 40,000 years ago. The Komodo dragon poses relatively little threat to humans and usually only bites when cornered. But Megalania, whether or not it was a deadly drooler, would have been a lizard to be very, very afraid of.
| NAME | sawfish Pristis species |
| LOCATION | shallow, warm coastal waters |
| ABILITY | using its saw for slashing and sifting |
© Marty Snyderman/imagequest3d.com
A sawfish has external teeth, set around a sensitive, flat snout – the saw, or rostrum (here shown from the underside). Swung from side to side, the saw can be used as a powerful weapon to slash shoaling fish such as mullet and herring, which it then eats off the sea-bottom. Generally speaking, though, the sawfish is a slow and peaceable animal, spending its time in shallow, muddy water, raking the mud with its saw for crustaceans and other prey. The saw-teeth get worn by all this grubbing, but they grow continuously from their bases and so don’t wear out.
Like its close relatives, the rays, it’s perfectly camouflaged against the bottom of the sea, and like its more distant relatives, the sharks, it swims in an undulating way. And like both groups, its hard bits are cartilage, not bone, and its teeth are adapted scales. It has another similarity. Using special cells, the ‘ampullae of Lorenzini’, on its saw and head, it can detect electrical fields generated by prey.
One problem for females is that they give birth to live saw-babies. But a youngster’s saw is covered with a sheath to make birth relatively painless. A much greater problem for all sawfish (possibly seven species) is the fact that their coastal waters are being polluted and developed and that they have been overfished to the point where all are endangered, some critically. A sawfish’s saw is also its downfall. Not only has it been sought after as a trophy, but it also fatally entangles the fish in nets.
| NAME | titan arum, corpse flower, or devil’s tongue, Amorphophallus titanum |
| LOCATION | western Sumatra, Indonesia |
| ABILITY | pumping out the smell of decomposing flesh |
© Neil Lucas/naturepl.com
What smells bad to us often doesn’t bother other animals. In fact, the scent of the foul-smelling titan arum – the tallest and probably heaviest of flowering structures – is positively attractive to carrion beetles and bees. Whether its smell is the worst, to us, has still to be tested (there are other contenders for this, including the even bigger giant titan, A. gigas). But the titan arum produces a sufficiently awful smell to make people faint.
The ‘flower’, or inflorescence, comprises a vase-shaped spathe (petal-like leaf) at least 1.2m (4ft) tall, which grows rapidly from a gigantic tuber weighing up to 80kg (177lb). Out of this rises a spadix, a spike with thousands of tiny flowers more than 2.4m (8ft) tall, so strange it gives the arum its scientific name: ‘huge deformed penis’. The upper part of the spike produces the smell, and to make it travel further, the spadix generates heat and may steam at night as it pulses its fragrance of ammonia, rotting flesh and bad eggs for up to eight hours at a time.
This attracts pollinating, carrion-loving insects, but few people have observed the pollination, probably because the plant flowers only every 3–10 years and then for just two days. Once the flower dies and hornbills have dispersed its seeds, it’s replaced by a titanic leaf up to 6m (20ft) tall, which makes the food so that, one day, the tuber can grow another stinking flower.
| NAME | Chatham Island black robin Petroica traversi |
| LOCATION | Chatham Islands, east of South Island, New Zealand |
| ACHIEVEMENT | increasing in numbers from just five to 250 in 18 years |
© Don Merton
New Zealand’s Chatham Islands are believed to have been the last Pacific archipelago to be visited by humans. Yet when people finally did visit, they stayed, and they did a pretty thorough job of doing what humans have always done to islands: stripped them of a lot of their native plants and animals. The Polynesians arrived around 700 years ago, the Europeans came along in the 1790s, and between them they caused the extinction of 26 of the islands’ 68 species and subspecies of birds. The main cause was introduced land mammals, and among the sufferers from cats and rats in particular was the 15cm (6in) endemic black robin.
By 1900 it had disappeared from the two main islands and survived only on Little Mangere, a tiny, windswept stack with sheer cliffs that helped keep predators away but didn’t offer the birds much protection from the elements. By 1972 only 18 were left. By 1976, seven.
In the meantime, though, the government had bought nearby Mangere Island and begun to reforest it, and all the birds were moved there. Nevertheless, by 1980, there were just five, with only one breeding pair. But by fostering eggs to other bird species on other islands – which improved the survival chances of the chicks and spurred the breeding female to nest again – conservationists painstakingly cranked the species back to life. Now there are about 250 black robins on Mangere and South East islands, and there are plans to repopulate other islands in the Chathams.
| NAME | Pompeii worm Alvinella pompejana |
| LOCATION | deep-sea hydrothermal vents |
| ABILITY | withstanding scalding water |
© Peter Batson/imagequest3d.com
The Pompeii worm thrives in large colonies in one of the darkest, deepest, most hellish places on Earth – close to a geyser of water so hot it could melt the worm in a second. It is also subject to a pressure great enough to crush a person and doused in a soup of toxic sulphur and heavy metals. Communities of Pompeii worms cling to the sides of ‘smokers’ 2–3 km (1.2–1.9 miles) under the sea. These belching chimneys grow over hydrothermal vents on volcanic mountain ranges, created from the chemicals that precipitate out as 300°C (572°F) vent water meets cold seawater.
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