Blood, Bees and Bone: These 5 Animals Have Surprising Diets

Did you know that there's a plant-eating spider? How about a bird that prefers to eat bones?

Evolution occasionally produces something truly bizarre. Let's take a look at the weird eating habits of these 5 animals, including...

• The Bone-Eating Bearded Vulture
• The Vampiric Ant
• The Bee-Eating Buzzards
• The Snail That Eats Nothing
• The (Mostly) Vegetarian Spider

The Bone-Eating Bearded Vulture: The Bearded vulture is a mighty bird of prey with a wingspan of almost three meters - it should be able to take the choicest bits of carrion... but instead it dines on bones.

This isn't actually as insane as it sounds. While it's not uncommon for predators (or even other scavengers) to leave bones behind, they are filled with nutrient-rich marrow... and unlike other creatures, the bearded vulture has extremely potent digestive juices that can break down bone and unlock the goodness within. If a bone happens to be too large for the bird to swallow, the vulture solves the problem by flying high and dropping it onto rock!

Despite being a bone-eating scavenger, this bird has a sense of style. They deliberately dye their white feathers a rusty orange-red in iron-rich soil or water, if given the chance.

There's two competing theories as to why they do this - it could offer some protection against bacteria picked up when picking through corpses, or it might simply be a way of showing off to potential mates and rivals!

The Vampiric Ant: There are quite a few blood drinkers in the animal kingdom. Mosquitoes, leeches, vampire bats and even some moths have been known to sip from the veins of prey... but the "Dracula ant" goes a step further and consumes the blood of its own grubs.

This Madagascan insect is a pretty strange creature all round. The adults have powerful but overspecialized jaws (more on that later) and can't eat solid food. They hunt down and dismember prey, hauling it back to the nest for the grubs to eat.

Of course, the adults still need to feed somehow... so they gnaw and scrape at the flesh of their grubs until they ooze hemolymph (insect blood) to lap up. The procedure isn't fun for the grubs, which often attempt to wriggle away from their tormentor!

So why do the ants do this? Well, using the grubs as a kind of food processor allows adult ants to carry some of the fastest jaws in the world. Their springy mandibles are pressed together and store energy (a bit like how we can snap our fingers) that is released when they slip past each other. The resulting "bite" has a peak velocity of 90 meters per second, sending stunned prey flying and actually making the ant recoil!

The Bee-Eating Buzzards: Birds of prey normally go after small mammals, birds or even reptiles. That's not the case when it comes to the honey buzzards, predatory avians that rip apart hives and feast on bee, hornet and wasp grubs.

Like something from a horror movie, the buzzards lurk in the woods and wait for an unsuspecting insect to fly past. Rather than attacking, the bird trails its mark back to the nest. The buzzard then rips into the nest with powerful talons and tears out chunks of honeycomb filled with grubs.

The insects don't take kindly to this intrusion, but they lost the battle before it began. Honey buzzards have short, dense feathers that protect their face from stings, tough nictitating membranes (a third semi-transparent eyelid - humans only have the remnants of one) to protect the eyes and tough scaly skin on their feet. The end result might as well be a tank, from the perspective of the defending insects!

The Snail That Eats Nothing: In the lightless depths of the sea, the scaly-foot snail lives amongst chemical-spewing hydrothermal vents. You might wonder where a snail 2400m below water finds food - and the answer is that this creature doesn't seem to eat anything at all!

The snail has a highly specialized digestive tract, with an atrophied digestive system and radula - or to put it simply, it has tiny mouthparts and almost no stomach. Instead, the snail's esophagus is massive and filled with chemosynthetic bacteria - and the snail absorbs chemicals through its gills and pumps them to the bacteria. The bacteria turn these chemicals into energy, some of which is siphoned off by the snail.

There's a single wrinkle in the snail's feeding method - the bacteria produce sulfur, which can be quite lethal if it builds up. Fortunately the snail's scales are filled with tiny channels that siphon out the toxic mineral. This expelled sulfur combines with iron in the water and "plates" the snail's scales with iron sulfide, giving it an armored foot!

The (Mostly) Vegetarian Spider: Some spiders trap prey in webs, others hunt on foot and pounce at their victims... but one spider prefers to take the vegetarian option.

While several spiders supplement their diets with a bit of plant matter (usually nectar, sap and other fluids with the odd bit of pollen) the jumping spider Bagheera kiplingi feeds almost exclusively on a type of acacia.

These acacia trees produce little packages of protein and fat called "Beltian bodies" to attract ants. The insects live in a symbiotic relationship with the acacia, providing a vicious active defense against anything undeterred by thorns in exchange for food and shelter.

Like a porch pirate, Bagheera kiplingi steals these Beltian bodies for itself. This does put it in conflict with the ants, but the spider simply jumps out of the way of ant patrols or abseils to safety on a silk thread. They even make little silk dens to hide in!

Researchers speculate that these spiders once specialized in snatching ant grubs and eggs, before moving on to stealing Beltian bodies. They'll also still grab undefended grubs if they get the chance!

Thanks for reading - perhaps you'd also be interested in...

• Big Eater? These 8 Animals Hunt Prey Larger Than They Are!
• These 6 Animals Are Real-Life Vampires

Sources and Further Information:

• Bearded vulture
• Why do bone-eating bearded vultures stain their feathers rusty red?
• The Dracula ant that MUST drink the blood of its young to survive - despite causing them pain and trauma
• Dracula ant's killer bite makes it the fastest animal on Earth
• Honey buzzard
• Honey Buzzards Feast on Deadly Hornets
• Discovered in the deep: the snail with iron armour
• There are 40,000 spiders in the world - and just one is vegetarian. Weird right? However that's not its only oddity...