Image is everything – even in the animal kingdom, where survival of the fittest has taken on a whole new meaning. Conservation, it seems, is becoming a bit of a beauty contest. While it's not so difficult to interest the public in the plight of charismatic polar bears or cute pandas, plenty of, well, more homely species are also in danger of extinction but, being less photogenic, get much less media attention.

Last year on the Zoological Society of London's Edge website, which raises funds for animals on the verge of extinction, visitors could choose to donate cash to any of 10 individual species. Coming top in this endangered beauty pageant was the slender loris – a small, endearing primate with oversized eyes, like a character straight out of a Disney film. Bottom of the pile was the solenodon – a scruffy, ancient mammal with the front of a shrew and the back-end of a rat. Some animals, even ones on the brink of being wiped out, are apparently just too ugly to love.

This month the Zoological Society of London, prompted by news that 85 per cent of amphibians threatened with extinction were receiving almost no conservation, released a top 10 of cosmetically challenged salamanders and frogs. The list aimed to raise awareness of strange but unique creatures often overlooked in favour of the cute and the cuddly.

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"Traditionally, species have gotten noticed because we're innately attracted to them, like pandas, elephants and gorillas, which means we're more likely to get involved in their conservation," says Dr Jonathan Baillie, a scientist at ZSL.

The good news is that ugly is now set to be seriously fashionable in the animal kingdom. "I think we're now in an era where people want to be exposed to things that are different, new and often extreme," Baillie says. There's an appetite for [ugly] creatures."

The ZSL's aim is simple: to get would-be conservationists to overlook the fact that certain creatures have been tapped with the ugly stick and love them instead for their weird and wonderful attributes. "The transformation from ugly to cute can be amazing," says Baillie. "The film Shrek has done that beautifully, where you start with a creature that people think is repellent and by the end of the film they're in love. And that's the process we're going through with some species – we're Shrek-ing them."

Solenodon

The solenodon can be traced back to more than 70 million years ago to the age of the dinosaurs. Time, however, has done little to improve its looks. There are two types, the Hispaniolan and the Cuban, with the latter being the uglier owing to a pronounced rat-like appearance and scruffy, patchy fur.

"The Cuban solenodon looks like a giant dishevelled shrew," says Baillie. "We associate animals that are symmetrical and well-groomed as beautiful. So if something looks dishevelled we might think it has an association with disease."

The solenodon, which feasts on insects and can inject poisonous saliva into its prey, has been considered extinct at various times in the past century and is now classified as endangered. "In terms of ugly animals this one's a hero," says Baillie.

Aye-Aye

Look away now. The aye-aye is thought so frightening that it is killed on the spot in Madagascar. Locals there believe the primate is an evil omen.

"The aye-aye has these ominous eyes and long, bony fingers," says Baillie. "It really gives people a scare, plus it's nocturnal which means the aye-aye is seen as a stereotypical witch-like creature."

The aye-aye has an oversized middle finger, which is used to chip away bark, dig into trees and hunt for grubs. It is the largest nocturnal primate on the planet and is losing its forest habitat to agricultural development – as well as being hunted for its looks.

"The aye-aye is so unusual and wonderful," says Baillie. "The ugliness could really help the creature get noticed and raise its profile in terms of conservation."

Giant Salamander

A heavyweight amphibian which can grow up to 1.8 metres long and weigh in at 11kg, the Giant Chinese salamander's origins go back 170 million years. "Some have described the Giant salamander as a large, slug-like creature," says Baillie, "owing to the beady little eyes and stubby little fingers."

The population has dropped by 80 per cent since the 1960s and is considered critically endangered. The Giant salamander depends on freshwater systems in the Yangtze but has been threatened by pollution and intensifying industry along the river. There is also a lucrative industry in breeding the salamander and selling the meat.

"The Giant salamander looks like something that has come from the depths. But to think they were around before the dinosaurs!" says Baillie. "These things that we call odd and ugly are really the cornerstones of biodiversity."

Saiga Antelope

"I would put this in the unusual, almost cute category. You're not repulsed when you look at it. You think more of Star Wars," says Baillie of the saiga antelope's distinctive swollen proboscis.

The antelope's horns, which look like carrots, are highly prized in the medicinal trade. Hunters chase the antelopes in vehicles and either shoot them or run them over.

"If they die when they are excited and the blood is pumping then they are worth more. In the past, poachers collected them in thousands," says Baillie.

Found in Kazakhstan, with a sub-population in Mongolia, the saiga antelope population has had an "extreme crash" due to poaching. Cold winters and dry summers in Mongolia have also affected the species – it has now dropped from more than one million to just 50,000 in 10 years and considered critically endangered.

Myers' Surinam Toad

"It's got a sunken body and most people's first reaction is that it looks putrefied," says Baillie of the Myers' Surinam toad. The naturalist Gerald Durrell agreed, describing the toad as: "Looking... as though [it] had been dead for some weeks and was already partially decomposed."

Despite being perfectly healthy, the toad, found in Panama, has a habit of looking close to death. It can't sit up, lying, instead, pancake-flat. Its reputation isn't enhanced any further by its habitat – which is a swamp.

Numbers of the toads have been falling as deforestation threatens its habitat.

Long-beaked echidna

The echidna looks like a hedgehog, only bigger. It also has a long, pointy snout, small, beady eyes and no teeth; instead the tongue is covered in spikes. Its reptilian motion further enhances its strangeness. It is one of the few mammals to lay eggs and has a pouch to keep its young in. "It's one of the most evolutionary distinct animals on the planet," says Baillie.

Found in Papua New Guinea, locals hunt down the echidna with dogs for food. Edge is focusing on the Attenborough's long-beaked echidna, found on one peak in the Cyclops Mountains of Papua. It hasn't been seen since 1961. "When we recently went to look for it in the mountains where it was thought to be extinct, we found signs that it was still in the area and people had recently eaten them," says Baillie.

Northern hairy-nosed Wombat

A big, heavy marsupial, the Northern hairy-nosed wombat is critically endangered, with not many more than 100 left, in one fenced-off colony in Queensland, Australia. The largest of all wombat species, it has lost its home to farming and has been threatened by introduced animals such as the dingo. "This wombat has a really blunt head and stocky features," says Baillie. "It looks strange because people won't be familiar with seeing one before. It's got a great name, though."

Phoenix Fly

"The phoenix fly is not really ugly, it's just a rather dull-looking fly. A big, brown one at that," says Matt Shardlow, director of Buglife, a charity for conserving invertebrates. "Anyone would think it was a housefly."

The use of pesticides and fertilisers has driven the phoenix fly out of the British countryside and on to brown field sites as it prefers rough habitats, such as quarries, that aren't intensively managed and where there's plenty of bare ground to lay eggs.

The fly is dubbed "phoenix" after rising from the ashes of scrap-filled, unkempt locations. Now the redevelopment of brown field sites is threatening the phoenix fly again. "There are about 40 important species that all live on brown field sites, places that we don't think are attractive," says Shardlow. "They look messy but it doesn't mean they are not important for conserving biodiversity."

Mole Cricket

"It's weird – it looks halfway between a cricket and a mole," says Shardlow of the mole cricket. At six centimetres long, it's one of the biggest invertebrates in the UK, and has a velvety head and clawed feet like a mole.

The mole cricket spends most of its time underground, coming out at night. They were usually discovered when ploughing fields but the use of fertilisers and pesticides has seen the population plummet dramatically. Buglife reckons the UK population may now be extinct. "It hasn't been confirmed in the wild recently – there have been a few possible records. But the UK contingent has probably gone."

Glutinous snail

The glutinous snail is extremely rare in the UK and is in decline across Europe. Having previously been found in lakes in Oxfordshire and Snowdonia, it is now down to just one site, at Llyn Tegid (Bala Lake) in Wales. Although smaller than a garden snail, the glutinous snail gets its name for being extra slippery and slimy.

"It has a mantle which spreads out over the shell so it is encased in glutinous stuff," says Shardlow. "It's supposed to be an anti-predator device." The snail likes clear, isolated lakes but pollution has seen the population decline in the past 50 years.