Ruling a shrinking kingdom (Image: Frans Lanting/FLPA) Two giant damselflies, Coryphagrion grandis, caught in the act of mating (Image: Viola Clausnitzer) The leopard magpie moth Zerenopsis lepida, which uses poisonous cycads as a source of weapons (Image: Hermann Staude) The critically endangered mussel Margaritifera marocana. Fewer than 250 survive (Image: Mohamed Ghamizi) Advertisement

In Japan, the world’s governments are attempting to thrash out a plan to conserve our vanishing animal and plant life. While the politicians talk, biologists have released the latest figures on the state of the global ecosystem – and they are as grim as we have come to expect.

Some new numbers come from the International Union for Conservation of Nature (IUCN), which has added a swathe of animals and plants to its Red List of Threatened Species. Simultaneously, the Zoological Society of London (ZSL) has released a report titled Evolution Lost, which integrates the Red List with other data to paint a broader picture of the state of the vertebrates: everything from eels to elephants.

In total, 19 per cent of vertebrate species are threatened. Some of these are critically endangered, such as the cave catfish. Confined to one pool of water 2.5 metres by 18 metres across in a cave in Namibia, it faces sudden extinction if water extraction causes the pool to disappear.

Much less is known about the invertebrates, but ZSL estimates that at least 15 per cent are currently endangered.

Among plants, seagrasses have been assessed for the first time by the IUCN. They are declining at an unprecedented rate, says IUCN programme officer Heather Harwell: 14 per cent of these marine meadow species are endangered.

It’s not unmitigated bad news, though. Angelfish and butterfly fish have been assessed for the first time and are “mostly doing quite well”, says Harwell, with 93 per cent of angelfish species and 91 per cent of butterfly fish species rated as of least concern. And the marbled lungfish – a living piece of evolutionary history with the largest genome of any animal – is also rated as of least concern, despite being commonly eaten by humans.

The world is a storehouse of beauty and variety that we are depleting before we have truly explored it

Such infrequent upsides aside, the numbing statistics of species in peril can mask a simple truth: that the natural world is a storehouse of beauty and variety that we are depleting before we have truly explored it. So to get beyond the impersonal numbers, we present four snapshots of little-known species that face deadly threats.

Damselflies in distress Dragonflies and damselflies have shrunk since the time when some had wingspans of 70 centimetres, some 300 million years ago, perhaps because the atmosphere nowadays has less oxygen to power such monstrous insects. But a few modern species carry on the supersize tradition. One is the African damselfly Coryphagrion grandis (see picture), which has a body up to 12 centimetres long. All the other giant damselflies live in South America. It seems the African species is a relative that got separated from its brethren when the two continents broke apart 120 million years ago. In a reversal of the natural order of things, these flies feed on spiders, hovering in front of their webs and plucking the luckless arachnids from their perches. Their young live in water, normally in pools between the roots of trees or in hollowed-out trunks, and sometimes in discarded coconut shells. The larvae are carnivores, and not above eating each other. As a result, it is rare to find more than one larva in a single tree hole, says damselfly expert Viola Clausnitzer. Damselflies live in coastal forests that once formed a continuous belt in east Africa but are now fragmented, forcing the creatures into small, vulnerable populations.

Toxic demand Cycads are the oldest seed-bearing plants on Earth. They deter many animals from eating them by filling their leaves with toxins. But this ancient chemical defence may not be enough to save them from humans. The Natal grass cycad is particularly poisonous, says John Donaldson of the South African National Biodiversity Institute. It manufactures toxic and mutagenic chemicals called macrozamin and cycasin. The toxins in its leaves are used to defend more than just itself: the colourful leopard magpie moth (see picture) feeds on cycads as a caterpillar in order to lace its body with macrozamin, making it a deeply unpalatable meal for any would-be predators. While the Natal grass cycad is not too badly depleted by nibbling caterpillars, and protected by its toxins from most other animals, the plant is widely harvested by humans. The roots are used in magical potions to ward off evil spirits and in medicines to induce vomiting. Demand is high, with over 3400 plants being sold in one month through two markets in KwaZulu-Natal, South Africa, alone. As a result, it is overharvested and is now classed as vulnerable. Its case is far from unique; the IUCN’s Red List classes an appalling 63 per cent of cycad species as threatened.

Mussels wasting away In 2006 a shell collector named José Ahuir got a shock. While searching the river Derna in Morocco, north Africa, he discovered a little colony of about 50 mussels that should not have been there, because they were thought to be extinct. Margaritifera marocana (see picture) is clinging to life after all, and while it was once thought to be a subspecies of a European mussel, it turns out to be a separate species. Small populations were also found in nearby rivers, but with fewer than 250 known individuals, the mussel is critically endangered. The Derna was once known as the River of Pearls, and pearl divers in the 19th century may have taken their toll. Nowadays the mussel faces pollution and dredging. These problems may be made worse because of its chosen method of transport. M. marocana cannot move around unaided, so to get its young to a fresh location it is thought to attach them to passing fish, which then carry them upstream. Some other mussels lure fish in with fronds that look like small prey animals, and the microscopic larvae have hooks that grip the fish’s skin. We don’t know what fish is exploited by M. marocana, but it is likely to be suffering from the same problems of pollution and dredging. If the fish disappears, the mussels are doomed, says IUCN’s freshwater specialist William Darwall.