Mammals

Aye Aye: Gives Grubs the Finger
The Aye Aye is a primitive primate that has an unusual method of feeding. It taps trees listening for insects inside, gnaws a hole in the tree, and sticks its long finger into the hole to pull out the insects.

It fulfills the ecological niche of the woodpecker within its habitat range.

Wikipedia entry: http://en.wikipedia.org/wiki/Aye-aye

Tarsier: Huge Eyes
Tarsiers are a living fossil that represents an early lineage of primates.

They have massive eyes for seeing at night.

They also have excellent hearing and can emit and hear higher pitched sounds than nearly any other creature. They are the only entirely carnivorous primate.

Wikipedia entry: http://en.wikipedia.org/wiki/Tarsier

Platypus: Weirdest Mammal
The duck-billed platypus is a famously weird mammal. It is one of the only species of mammal that lays eggs. It has webbed feet and a leathery bill that resembles that of a duck. Males possess ankle spurs that are poisonous, which are used defensively.

The bill of the playpus has receptors that make it the only mammal that has a sense of electroperception, the ability to detect prey by detecting electrical impulses from their muscle contractions. It compensates for its poor eyesight by using its bill in the mud of rivers.

Wikipedia entry: http://en.wikipedia.org/wiki/Platypus

Fossa: Madagascar Cougar
The Fossa is the apex predator of Madagascar.

It is cat-like but is actually related to mongooses.

See also: http://animals.nationalgeographic.com/animals/mammals/fossa/

Wikipedia entry: http://en.wikipedia.org/wiki/Fossa_%28animal%29

Star-nosed Mole: Sees With Its Nose
The star-nosed mole has a nose with fleshy tentacles that is uses to visualize its environment. This nose is extremely sensitive with over 25,000 touch receptors. It is recognized in the Guiness Book of World Records as the World's Fastest Forager, because it can recognize a prey item in a lightning-fast 8ms.

Wikipedia entry: http://en.wikipedia.org/wiki/Star-nosed_mole

Pangolin: Armored Mammal
The pangolin wears a coat of armored plates that protect it from predators. When threatened, it can curl up into a tight ball.

Pangolins have long sticky tongues for capturing ants and termites like an anteater.

Wikipedia entry: http://en.wikipedia.org/wiki/Pangolin

Pink Fairy Armadillo: Pretty in Pink
Pink fairy armadillos are endemic to Argentina.

They are the smallest species of armadilo.

And they just look weird.

Wikipedia entry: http://en.wikipedia.org/wiki/Pink_fairy_armadillo

Narwhal: Unicorn Whale
The Narwhal is a whale in which males have a tooth protruding as a long tusk from its head, resembling a unicorn. The function of this tusk appears to be as a sensory organ.

The tusk is corkscrew-shaped.

Wikipedia entry: http://en.wikipedia.org/wiki/Narwhal

Naked Mole Rat: The Only Hive Mammal
Naked mole rats are unusual rodents from Africa. They look like something from a nightmare.

They do not regulate their temperature like most mammals. Their skin lacks the receptors necessary to feel pain. They are resistant to cancer, and are the longest-living rodents.

Uniquely among mammals, naked mole rats exhibit eusociality, in which a queen and a few males are responsible for reproduction in a colony, while the rest of the rats are workers. This is similar to the social structure of ants and bees.

Wikipedia entry: http://en.wikipedia.org/wiki/Naked_mole-rat

Slow Loris: Poisonous Mammal
The slow loris has a metabolic rate about 40% of that of most mammals, so it moves slowly and deliberately. It has a poison gland under its arm that it licks in order to deliver a poisonous bite, which is unusual among mammals.

Wikipedia entry: http://en.wikipedia.org/wiki/Slow_loris