The planet’s weirdest animals

Meet ten of the world’s strangest creatures and find out why they have evolved to be so odd

You probably think you’ve seen everything the animal kingdom has to offer. There are a million species of beetle, but they all basically look like beetles, after all. A little bigger here, a different colour there, perhaps some horns. But all quite recognisable. The animals that are most common in the world are those that exploit a wide ecological niche. They are familiar because they are successful, and because their evolution has supplied lots of very minor variations on those themes. But there are other animals that have evolved to exploit very specific niches. Specialists that live in some of the remotest, strangest and harshest environments on Earth. For these animals, the standard body shape and the normal lifestyle strategy just isn’t enough. They exist at the extreme edge of the natural selection envelope. Their bodies have distorted to such an extent that their common name often mistakes them for something else entirely: the toad that is really a lizard; the butterfly that’s a snail; the mole rat that’s neither a mole nor a rat. To us, they are weird. But if you lived where they do, you’d quickly realise there is simply no other way to survive.

Blowfish – Deep-sea gelatinous mass
The blobfish is adapted to live in water 0.8 kilometres (half a mile) deep. At this depth the pressure is 80 times higher than at sea level and a normal gas-filled swim bladder is almost useless. Most creatures at these depths give up trying to swim entirely and simply walk or flop along the seabed. But flopping requires more energy and the blobfish is much too lazy for that. It has traded almost all its muscle mass for a jelly that is just slightly less dense than water. This allows it to coast just above the ocean floor. It doesn’t chase its prey, but simply swallows anything that’s slow or careless enough to get in the way of its mouth. Unusually for a fish, the female ‘sits’ on her eggs, instead of just abandoning them after laying. This is probably to protect them from being eaten by other blobfish in the vicinity.

Star-nosed mole – 22 fingers attached to its nose

The star-nosed mole is the world’s fastest-eating mammal. It takes less than a fifth of a second for it to identify if an object is edible and gobble it up. The secret is the ring of 22 tentacles around its nose. These are covered with 25,000 super-sensitive touch receptors, called Eimer’s organs. Working in total darkness in a tunnel, or underwater, the mole can discriminate between an edible larva and a stone or empty shell in 17 milliseconds. This is so fast that its brain is working almost at the physical limit of the nerve fibres. Star-nosed moles use this ability to eat very small insects and crustaceans that wouldn’t be worth the effort for a slower diner. They are also excellent swimmers and maintain a network of riverbank tunnels up to 270 metres (886 feet) long.

02 Jun 2009 --- Star-nosed Mole (Condylura cristata). --- Image by © Ken Catania/Visuals Unlimited/Corbis
The world’s fastest eater…

Frill-necked lizard – Wears an Elizabethan collar

Frill-necked lizards are almost a metre (3.3 feet) long with colours ranging from green to dark orange. They are all the same species though; the colour varies to match the local vegetation. Frill-necked lizards have a fan of cartilage spines around their head, supporting a wide flap of skin. The spines are connected to the base of the tongue so, when the lizard gapes its mouth, the frill spreads wide. This is used to scare away predators and also for courtship signalling. They are also the only lizards that can balance properly on two legs; other lizards can run on their hind legs but they fall forward as soon as they slow down.

Frill-necked Lizard (Chlamydosaurus kingii). Northern Territory, Australia
Frill-necked Lizard – can run on two legs

Aye-Aye – Woodpecker fingers

The aye-aye is the largest nocturnal primate. When leaping from tree to tree, it uses its excellent night vision, but when hunting for food it switches to a form of echolocation. Aye-ayes eat insect larvae that burrow in tree trunks. To find them they use their middle finger, which is especially long, as well as thin and bony. By rapidly tapping on the trunk they send vibrations through the wood. After each tap, the fingernail drags lightly along the bark to sense the return echoes and the aye-aye’s huge ears enfold the target area to listen for changes in the pitch of the drumming sound. When it finds a hollow channel, the aye-aye uses its forward-slanting teeth to gnaw a hole in the bark and its long finger then does double duty as a specialised winkling tool to extract the juicy grub inside.

B361KF Young Aye-aye born in captivity UK. Image shot 04/2005. Exact date unknown.
Aye Ayes use their fingers to detect hidden food

 

Red-lipped batfish – A walking fish with lipstick

This fish lives on the rocky seabed of the Pacific. Because the floor is rough and spiky, it prefers not to swim along the bottom like a flounder – instead it has evolved pectoral fins that work like legs to ‘walk’ along the seabed. It doesn’t use its dorsal fin for swimming either; this has evolved into a spiny projection with a retractable ‘fishing rod’, which it uses to lure in small fish and shrimp. And the bright red lips? It turns out they really do perform a similar function to lipstick. The batfish uses them to help improve species recognition when searching for a mate.

07 Apr 2007, Ecuador --- Red-Lipped Batfish on Ocean Floor --- Image by © Visuals Unlimited/Corbis
Give us a kiss!

 

Honeypot Ant – A living larder

Ants of the genus myrmecocystus use specialised workers, called repletes, as living food stores. Their abdomens are inflated to a huge size with a pressurised gas bubble that is gradually displaced by a sugary liquid. To avoid wasting energy, the repletes barely move and spend the rest of their lives clinging to the ceiling of the nest in clusters. When a worker needs food, it strokes a replete with its antennae and it regurgitates a mouthful. If they fall from the ceiling, they can’t climb back up and instead are dismembered by the workers. The balloon of food remains on the nest floor for a week or more as the workers gradually transfer its contents to other repletes. A single colony can have 1,500 repletes that hold up to a kilogram (2.2 pounds) of stored food between them.

A0WP7N Honey Pot Ant (Myrmecocystus spp )with engorged gasters - Arizona
Specialised workers called repletes are living store cupboards

 

Sea butterfly – Upside-down swimming snail

Thecosomata are sea snails about the size of a lentil, with shells so thin that they are virtually transparent. Rather than sliding on the seabed, their foot has evolved into a pair of thin ‘wings’ that flap through the water. Sea snails mostly swim upside down because their body and shell is heavier and hangs down from the wings. They are herbivores, feeding on phytoplankton, but they catch their food in webs, like spiders. These webs are made from strands of mucus that can extend out as far as five centimetres (two inches) from the sea butterfly. They are preyed on by a kind of swimming sea slug called a sea angel.

Common Name: helicid pteropod, sea butterfly, Scientific Name: Limacina helicina, Magnification: 2x

 

Texas horned lizard – The ultimate blood-shot eyes

The horned lizard is camouflaged, spiky and can inflate itself like a pufferfish. But just in case that isn’t enough to deter predators, it has one last defence to deploy. By closing off certain blood vessels, the horned lizard abruptly increases the blood pressure in its head. This ruptures capillaries near the corners of its eyes and a jet of blood squirts from each, as far as 1.5 metres (five feet). In a single squirt, the lizard can lose a third of its total blood. Texas horned lizards eat Maricopa harvester ants, which have the most toxic venom of any insect. But far from poisoning the horned lizard, these toxins are stored and injected by special glands into the liquid projectile to cause a nasty burn.

AD6R7R Texas Horned Lizard New Mexico USA Cooling evaporatively Gray Ranch Nature Conservancy PreservePhrynosoma cornutum
When threatened, these lizards shoot blood from their eyes…

 

Naked mole rat – Rodents that live like bees

The nest of a naked mole rat is really not a comfortable place. The network of tunnels under the East African grassland is baking hot by day, freezing at night and almost airless. Life is so harsh that the naked mole rat lives as a hive organism with sterile workers and a single breeding queen. Naked mole rats can run backwards just as fast as forwards and have no sense of pain in their skin. Their metabolism is 30 per cent slower than other mammals of their size. Surprisingly, they have the longest rodent life span (28 years) and never get cancer.

CRXC68 Naked mole-rat, Heterocephalus glaber, South Africa
Could this be the world’s ugliest rodent?

 

Hairy frog – Wolverine of the amphibian world

This 11-centimetre (4.3-inch) frog appears to have tufts of hair on its sides and thighs, but they are actually dermal papillae – fleshy outgrowths that contain arteries. They act to massively increase the skin surface area, which allows the hairy frog to absorb more oxygen when sitting underwater. But it’s not just its ‘sideburns’ that make the hairy frog resemble X-Men’s Wolverine. It can also extrude sharp claws by intentionally forcing them through its skin. The spines are normally held in place with a ligament but, when threatened, the frog clenches its fist so forcefully that the ligaments snap and pierce its skin. Unlike Wolverine, the spines can’t be actively retracted; they just ease back over time and the skin regrows over them.

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The hairy frog can extend Wolverine-like claws

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