Animals | Erin Zimmerman

February 14, 2013

The Old Girls’ Club

Common Name: African Elephants, Asian Elephants

A.K.A.: Loxodonta africana, Elephas maximus

Vital Stats:

Comprise the entirety of Family Elephantidae and Order Proboscidea
African elephants are thought by some to be two species; the African Forest Elephant, and the African Bush Elephant
Can live for up to 70 years in the wild
The largest living terrestrial animals, reaching heights of up to 4m (13’) and weights of up to 7000kg (15,000lbs.)
Consume up to 150kg (330lbs.) of food daily

Found: Savannahs, bushlands, and forests in sub-Saharan Africa and Southeast Asia (but sparsely across these regions)

It Does What?!

Everyone knows elephants are cool. And weird looking. What they don’t tend to get a lot of credit for is just what complex lives they live, and how well-adapted they are to their surroundings. Far from being the dim, bovine, eating machines they’re often depicted as, elephants have been found to have an intelligence and self-awareness ranking up around that of primates and cetaceans, with comparably nuanced societies.

caption(Via:) — Jumbo renounces vegetarianism.
(Via: One Big Photo)

Elephant herds are matriarchal, being led by the oldest female and consisting of her close female relatives and their young offspring. Males are given the boot around the time they reach sexual maturity during their teens (because even the most intelligent animals find teenage boys a trial) and live the rest of their lives either alone or with a small pack of other exiled males.

Good parenting and discipline (delivered by mom with a swat of the trunk) seem to be extremely important for young male elephants; when orphaned males were introduced to a game reserve in South Africa in the late ‘90s, they immediately began going on killing sprees, hunting down and violently killing over 30 (endangered) rhinos, a completely abnormal behaviour for an elephant. As soon as well-adjusted adult males were introduced, the aggression stopped. Everybody needs a good role-model, I guess.

You may have heard stories about so-called “elephant graveyards,” where elephants go to die and leave remains near those of their relatives. While these have now been found to be a myth, appearing due to large die-offs happening suddenly in times of drought, it’s true that elephants show an inordinate amount of interest in the carcasses and bones of other elephants. Presented with a set of bones, elephants will become highly agitated and touch the bones repeatedly with their trunks, especially the dead animal’s tusks. Researchers speculate that this is because the tusks feel the same as they did in life, and touching is such an important aspect of elephant society. They are the only known animal outside of humans to take a particular interest in the bones of their species.

And what about their most obviously bizarre feature? How did a prehensile nose develop?! It’s hard to say for sure, but one interesting theory comes from the fact that elephants use their trunks as snorkels while swimming, sometimes crossing shallow lakes by simply walking across the bottom with only their noses above water. Given that manatees are one of elephants’ closest relatives, some scientists have speculated that elephants evolved from aquatic mammals, slowly becoming terrestrial, but never losing their once-important snorkel. (Or their internal testicles, another trait associated with an aquatic lifestyle.) Other scientists think those guys don’t know what they’re talking about and lack evidence to support this theory. So it goes in science.

Whatever their origin, elephants’ trunks have become enormously important in their lives, and are used in everything from eating to fighting to bonding with family members. Actually a fusion of the nose and upper lip, trunks have over 100,000 muscles and are sensitive enough to crack open a peanut shell and retrieve the seed from it. The ability to grasp comes from one or two (in Asian and African elephants, respectively) finger-like extensions at the trunk’s tip. These “fingers,” combined with the elephants’ high degree of intelligence, have allowed them to learn the use of several tools, including tree-branch fly-swatters, which they probably invented millions of years before we came up with the idea. Different priorities…

caption(Via: Wikimedia Commons) — Yeah, we definitely need a few more of these.
(Via: Wikimedia Commons)

And finally, let’s not forget the dearly departed cousins. While African and Asian elephants are the only remaining species of Proboscidea, the order containing both mammoths and mastodons, there were once over 160 of them, inhabiting every continent except Australia and Antarctica. Most of these persisted until the most recent ice age killed off nearly all of the largest mammals. Some systematists believe that Asian elephants are in fact more closely related to woolly mammoths than they are to African elephants, and it’s even been speculated that a cloned mammoth could some day be gestated in the womb of an Asian elephant. ‘Cause if we learned anything from Jurassic Park, it’s that reanimating extinct megafauna is a great idea.

Fun Facts:

Elephants use ‘seismic communication,’ transmitting messages via a low-pitched rumble, which is detected by distant elephants using the pads of their feet.
While they can move surprisingly quickly, elephants don’t technically “run,” due to the fact that their legs never all leave the ground simultaneously.
It’s a common myth that elephants get drunk eating fermented marula fruits which have fallen to the ground. Given the low level of alcohol which accumulates in rotting fruit, an animal the size of an elephant would have to eat an unrealistically huge amount in a short time to reach a high enough blood alcohol level. But they do seem to enjoy them as a snack.

Says Who?

Choi (2011) “Woolly Mammoths Could Be Cloned Someday, Scientist Says”. Live Science.
McComb et al. (2006) Biology Letters 2: 26-28
Morris et al. (2006) Physiological and Biochemical Zoology 79(2): 363-369
Shoshani (1998) TREE 13(12): 480-487
Shoshani & Tassy (2005) Quaternary International 126-128: 5-20
Shoshani et al. (2006) Brain Research Bulletin 70: 124-157
West (2002) Physiology 17: 47-50

February 6, 2013

The Life and Times of the Last Earthpig

Common Name: The Aardvark

A.K.A.: Orycteropus afer, Family Orycteropodidae

Vital Stats:

Also referred to as the “antbear” or “earthpig”
Common name derives from Afrikaans words meaning ‘earth’ and ‘pig’
Habitats include savannas, grasslands, and woodlands
Weighs 40-65kg (88-140lbs.) and can grow up to 2.2m (7’3”) long
Can live up to 24 years in captivity
Nocturnal, feeding only during the evening and at night

Found: Sub-Saharan Africa

It Does What?!

Like the platypus and several other creatures we’ve looked at, aardvarks are considered “living fossils,” organisms which have changed little from the way they looked millions of years ago (around 20 million, in this case).

Aardvarks don’t look much like most mammals of today, other than a passing similarity to the South American anteater, to which it isn’t closely related. In fact, aardvarks aren’t particularly closely related to anything. Not only are they the sole species in their genus, but they have their own family and order as well. This is because everything else that used to inhabit these ranks has since become extinct. At one time, there were at least 14 different species in the aardvark family, spread over parts of Africa, Europe, and Asia; but today, there’s just our friend the earthpig. Strangely, among the aardvark’s closest living relatives are manatees and elephants (all part of the motley superorder, Afrotheria), which suggests just what distant cousins they must be.

Okay, so aside from having outlived its family members, what’s so interesting about these things? Well, one look at them will tell you they must have evolved to fit some unusual lifestyle. Aardvarks are myrmecophagous, meaning they specialise in eating ants and termites, and nearly everything about that odd little body is geared to this task. First, finding their insect food means digging into large anthills and termite mounds, so aardvarks have become prodigious diggers, tunnelling at rates of up to two feet in 15 seconds with their heavily clawed feet. They use this skill in creating their underground burrows as well, excavating tunnels up to 13m (43’) long and even changing their home’s layout from time to time. Because, you know, you get tired of the same old thing…

Moving further up, the aardvark’s narrow, elongated head and long, snake-like tongue are perfect for dipping into the minute passages made by ants and termites. They even have a special sticky saliva that adheres to ants at a touch. In a single night of feeding sessions lasting from five seconds to two minutes per stop, an aardvark can attack 200 hills, consuming as many as 50,000 insects. The ants and termites try to fight back, of course, but the aardvark has thick, tough skin and can seal its nostrils shut, making bites and stings ineffective.

There’s just one feature of the aardvark that doesn’t make a lot of sense for its insect-eating lifestyle, and that’s a set of back teeth. (In fact, they’re are born with front teeth as well, but lose them at maturity.) No other myrmecophage on Earth has a functional set of teeth… you just don’t need ‘em to eat ants. So why do aardvarks have them? A little thing called the Aardvark Cucumber!

In a bonus piece of evolutionary weirdness, aardvarks supplement their diet with a single type of fruit, a cucumber which has now become entirely reliant on hungry aardvarks for its continued existence. The plant flowers above ground – as plants do – but then pushes itself into the earth as it sets fruit, resulting in a subterranean fruit. These cucumbers are dug up by aardvarks and eaten as a source of moisture, while the seeds go undigested and are conveniently deposited elsewhere with a ready source of fertiliser for germination. Without the aardvark, seed dispersal would be impossible, and new plants would be unable to obtain enough water and nutrients to survive.

So there you have the life of the lonely aardvark… enemy of the ants, saviour of the cucumber, brother to no one.

[Fun Fact: If pursued into its burrow, an aardvark will protect itself by sealing off the tunnel behind itself and digging further into the ground in the other direction.]

[Also… On their front feet, aardvarks have lost their equivalent to our thumb, retaining only four digits.]

Says Who?

Endo et al. (2003) Annals of Anatomy 185: 367-372
Lehmann et al. (2004) Journal of African Earth Sciences 40: 201-217
Lehmann (2008) Fossil Record 11(2): 67-81
Taylor et al. (2002) Journal of Arid Environments 50: 135-152
Taylor & Skinner (2003) Journal of the Zoological Society of London 261: 291-297

January 30, 2013

Living in Filth and Looking Up at the Stars

Common Name: Dung Beetles

A.K.A.: Subfamily Scarabaeinae

Vital Stats:

Many subsist entirely on faeces, while others also consume fungi and decaying plant matter
Found in extremely diverse habitats, on all inhabited continents
Grow up to 6cm (2.4”) long, and can live for up to three years

Found: Across the temperate and tropical regions of the world

It Does What?!

Dung beetles… if you believe in reincarnation, these are why you try to stay on the straight and narrow. Otherwise, you might end up coming back as a creature whose life quite literally revolves around excrement. Dung beetles owe their entire existence to the fact that larger animals have inefficient digestive systems, consuming manure for its remaining nutrients and even laying their eggs inside it as food for their future young. Gross, yes, but once you get past the “ick” factor, it’s a pretty practical system.

Dung beetles come in three main varieties: rollers, tunnellers, and dwellers. Rollers, which are the type most people are familiar with, roll faeces into small balls which they roll away with them to consume and bury elsewhere. Tunnellers dig under the dung, burying it on site as an underground food source. Dwellers, the slackers of the dung beetle world, don’t bother with burying their treasure, preferring to simply live in it where it falls. I’ll focus on the rollers from here on in, as they’re the most bizarrely specialised of the bunch.

Dung beetles find their warm, fresh meals either through their excellent sense of smell or, in the case of some species, by simply riding around on their chosen food provider until the right time comes. Studies have shown that the beetles prefer omnivore or herbivore droppings to those of carnivores, perhaps for the more easily-digestible plant matter. One particularly intrepid group of researchers even determined that human faeces are favoured above those of most other large mammals. Good job, guys. Your funding agency must be proud.

It's a hot commodity... so to speak.(Via: Wikimedia Commons) — It’s a hot commodity… so to speak.
(Via: Wikimedia Commons)

Rollers immediately set to work on a new pile of droppings by shaping a dense little ball of up to ten times their weight (about TimBit sized, for you Canadians out there. Mmm!). Before rolling the ball away to be eaten/buried for later, the beetle will climb up on it and do a sort of dance, rotating around its top. Researchers also observed the beetles doing this dance if their rolling path was disturbed, or if another beetle stopped them to try to steal their ball.

So why the dance? As you might guess, it’s a means of getting their bearings, but what’s really fascinating is how they’re doing it. Dung beetles always roll their balls in a straight line directly away from its origin, probably as a means of reducing competition from other nearby beetles as quickly as possible. And they do this despite facing the ground as they roll the ball with their hind legs. During the day, this was fairly obviously accomplished by positioning themselves according to the direction of the sun, using their dorsal vision. However, they can also do it on a clear, moonless night. How?

Using a planetarium and a series of experiments which, hilariously, involved fitting the dung beetles with little cardboard hats to block their overhead vision, a South African researcher has determined that the beetles are actually using the light from the Milky Way to navigate. This is the only known instance of animals using an entire galaxy to orient themselves. Birds and seals have been known to use stars for positioning, but never the Milky Way itself. This from a tiny creature that cleans up piles of poop for a living… there’s probably an inspiring metaphor here somewhere.

Goes great with coffee!(Via: Wikimedia Commons) — Goes great with coffee!
(Via: Wikimedia Commons)

In the “But what does it do for me?” department, dung beetles are actually immensely useful to humans. Beyond restoring important soil nutrients, in areas of intense cattle-grazing, the beetles cart off and bury literally tonnes of manure that would otherwise host dangerous parasites and disease-carrying flies. Australia has intentionally introduced African dung beetles for this express purpose. Results have been much better than certain other introductions there.

The value of dung beetles has apparently been recognised for a very long time. Ever heard of the sacred scarab beetles of ancient Egypt? Yep… they’re dung beetles. One and the same. The beetles represented transformation and were linked with the god of the rising sun, who was believed to remake the sun and roll it across the sky each day, like the beetle with its ball. Something to think about next time you’re watching a beautiful sunrise.

[Fun Fact: Dung beetles in the African savanna use their dung balls as thermal refuges, periodically climbing up on them to moisten and cool their feet, which can increase in temperature by as much as ten degrees as they travel over the hot ground.]

Says Who?

Baird et al. (2012) PLoS ONE 7(1): e30211
Chamorro-Florescano (2011) Evolutionary Ecology 25: 277-289
Dacke et al. (2013) Current Biology 23: in press
Smolka et al. (2012) Current Biology 22(20): R863-R864
Whipple & Hoback (2012) Environmental Entomology 41(2): 238-244

December 12, 2012

Hidden Kingdom, Part Two

Common Name: Leafcutter Ants

A.K.A.: Genera Atta and Acromyrmex of Tribe Attini

Vital Stats:

Fungi grown by leafcutter ants come from the family Agaricaceae
Ant species can maintain their association with a specific fungal cultivar for millennia
Neither the ants nor the fungal cultivars can survive outside of the symbiosis
Some ant species are capable of completely defoliating a small tree in under a day

Found: Humid forests of Central and South America

It Does What?!

Last week, we looked at leafcutter colonies, their various castes, and the impressively long lives of ant sperm. But obviously, leafcutter ants are known principally for one thing- cutting leaves. This they do on a grand scale, forming lines of thousands upon thousands of ants, dutifully toting chucks of foliage back to their colony. Why? To fertilize their fungus, of course! Much as we like to think of agriculture as one of the crowning achievements of mankind, the fact is, ants came up with it much earlier than we did. About 50 million years earlier, actually. (But they haven’t figured out how to deep-fry anything yet, so there’s that, I guess.)

caption (Via: Wikimedia.org) — The fungus is hungry.
(Via: Wikimedia.org)

When a young queen leaves her original colony to found a new one, she carries in her mouth a small piece of fungus to use as a starter culture (think yogurt or sourdough bread) for the colony’s gardens. Initially, she will care for this culture alone, but once the first generation of workers is born, they will take over the task from that point on. Since fungi don’t photosynthesize, they’re perfectly happy in a pitch-black underground garden, but they still need nutrients with which to grow, and dead vegetation is their food of choice. As the larger worker castes return with leaf (and flower) fragments up to three times their own mass, the minima gardeners clean away any outside fungal spores and chew the vegetation into smaller and smaller pieces. They then mix the shredded leaves with fungus and add the mixture to the garden. And, just for an extra fertiliser kick, they mix in their own faeces. Waste not, want not, right?

With all the workers coming and going, and so much foreign vegetation entering the colony, infections of the garden by competing fungal spores are inevitable, despite the ants’ best efforts. One such invader is the fungus Escovopsis, a parasite of other fungi, which can decimate a colony’s food supply and, in the case of young and vulnerable colonies, sometimes cause them to fail entirely.

But the ants have a secret weapon: bacteria. These adaptive little farmers actually carry around a ready supply of antimicrobial compounds right on their bodies. The bacterium in question, Pseudonocardia, grows directly on the ants’ exoskeletons and, researchers suspect, is nourished by a substance excreted through the ant’s glands. In return, Pseudonocardia produces a compound that the farmers can spread on invading fungus, killing it without damaging their food source. Symbioses within symbioses… and these are just the ones we know about.

Meanwhile, outside the colony, another fascinating parasite threatens the workers. Known as phorid flies, or ant-decapitating flies, you can probably guess why these things are a problem. Female phorid flies land on the backs of the larger worker ants as they travel to and from their leaf harvesting sites, laying eggs on the worker’s thorax. Once the eggs hatch, the larvae work their way into the ant’s head and start to eat the tissue surrounding the brain, eventually moving on to the brain itself (causing aimless wandering behaviour similar to that caused by the zombie ant fungus). Finally, the young parasites secrete an enzyme which causes the ant’s head to fall off completely, leaving them a convenient vessel in which to finish their development into adults.

Not to be outsmarted (by anything, apparently), leafcutter ants instituted a policy of defensive piggyback rides. Workers on the foraging path carry tiny minima ants on their backs as they travel. The minimae are too small to be useful hosts for the phorid fly, and so are able to fearlessly attack the flies as they approach, keeping the foragers safe. And not to lose an opportunity for increased efficiency, the little passenger will also begin cleaning the leaf fragment as the larger worker carries it home.

So there you have it. Leafcutter ants form colonies of millions, assign specialised tasks to different classes of citizens, grow their own crops, excel at problem-solving, and know how to use antibiotics. Next to humans, they form the largest and most complex societies on Earth. Forget robots and computers, people- if anything’s going to gain sentience and overthrow humanity, my money’s on the ants.

[Fun Fact: They compost, too. At least one leafcutter species maintains ‘outdoor’ waste heaps of discarded leaves and fungus. Special disposal workers (often old or unhealthy ants) turn the heap regularly to speed up decomposition.]

Says Who?

www.antweb.org
Marietta College Leafcutter Ant Page
Dijkstra & Boomsma (2006) Insectes Sociaux 53: 136-140
Evison & Hughes (2011) Naturwissenschaften 98: 643-649
Evison & Ratnieks (2007) Ecological Entomology 32: 451-454
Holman et al. (2011) Molecular Ecology 20: 5092-5102
Mueller et al. (2008) Evolution 62(11): 2894-2912

December 5, 2012

Hidden Kingdom, Part One

(Via:) — (By: Tobias Gerlach & Jenny Theobald, Via: deepgreenphoto.com)

Common Name: Leafcutter Ants

A.K.A.: Genera Atta and Acromyrmex of Tribe Attini

Vital Stats:

47 species; 15 in Atta, 36 in Acromyrmex
Atta ants have three dorsal spines and a smooth exoskeleton, while Acromyrmex ants have four spines and a rough exoskeleton
Less than 5% of new queens are able to build a successful colony
A maxima may have a head width of up to 7mm (0.28”), while a minima reaches less than 1mm (0.04”); mediae fall somewhere in between

Found: Humid forests of Central and South America

It Does What?!

Once in a while, I come across a species that’s just so strange and interesting, a single post doesn’t seem to do it justice. With that in mind, welcome to part one of the wonderous life of the leafcutter ant.

Let’s begin at the start of it all – a new colony being founded. This happens when a fertile, winged female and several fertile, winged male ants (called drones) are born and grow to maturity. One day, the winged crew will fly away together and engage in what’s called a nuptual flight, where the female mates with several different males (up to seven in some species) while in mid-air. Having accomplished what is literally their only purpose in a short, glorious life, the drones promptly die, while the new queen scouts out a good place to start her colony. Finding it, she yanks off her own wings, never to fly again, as her body starts to break down her flight muscles, using the energy to produce eggs.

Ant reproduction is remarkable in that actual mating occurs only once in the queen’s life. The males of her nuptual flight together provide hundreds of millions of sperm that will be the basis for the entire colony to come. At the risk of sounding like a weirdo, ants have amazing sperm. A human sperm cell, under ideal conditions, can survive for up to five days. If they don’t get the job done in that time, they’re finished. The sperm of leafcutter ants, having been collected by the queen, can live for up to thirty years. That’s probably older than a lot of the people reading this. They can spend decades just waiting around in storage for the egg with their name on it. And that’s not all- they come armed. As in, chemical warfare. The seminal fluid of ants contains compounds that can lower the survival of rival sperm (from other drones) while not harming those of the ant they came from. Weaker sperm are thereby killed off early in the game. Of course, this kind of thing doesn’t go on for a long time. The storage organs of the queen contain their own fluid that will neutralize chemical weapons on the way in. Think of it as the metal detector at the door.

Right. So the queen has her new place picked out and the on-site sperm bank is up and running. Time to make a colony. What she needs first are workers. In a small chamber she’s excavated underground, she begins to lay large numbers of eggs. These serve two purposes, because the early hatchers will eat the late hatchers until the food supply gets built up. It pays to be a bit premature when you’re an ant.

Nearly every worker born to the queen over the life of the colony will be a sterile female, and each will belong to one of three major castes- minimae, mediae, and maximae. These castes will dictate both their size and function in life. Sensing the needs of the colony, the queen can actually control which type of worker she is producing. First come the minimae, which are the smallest caste and will principally tend the underground gardens which are the colony’s food source (more on ant agriculture in part two), as well as acting as nurse-maids for growing larvae. Next are the mediae, which are larger and act as the colony’s foragers, bringing plant material with which to fertilize the gardens, and defending against minor threats or obstacles in the troop’s path. Finally, once the colony has reached a population of several thousand, come the maximae, or soldier ants. These big brutes are up to thirty times the mass of a minima and do all the heavy lifting, carrying bulky items, moving big obstacles, and cutting tough pieces of vegetation. They’re also the last line of defence when something serious threatens the colony or the foraging parties. And because ants are all about organisation, within each caste, there are numerous sub-castes which are responsible for specific duties, depending on which species we’re talking about.

Over time, leafcutter colonies can become impressively large, comprising over 5 million residents- the population of a major human city. It’s amazing to consider that these are kept running smoothly without central authority, technology, or the aid of written or spoken language. Not to mention opposable thumbs.

Tune in next week for a look at leafcutter agriculture, their interesting relationships with symbiotic fungi and bacteria, and why ants give each other piggyback rides to work.

[Fun Fact: The largest leafcutter ant colony on record required the excavation of approximately 40 tonnes (44 tons) of earth and contained thousands of different chambers.]

Says Who?

www.antweb.org
Marietta College Leafcutter Ant Page
den Boer et al. (2010) Science 327: 1506-1509
Dijkstra & Boomsma (2006) Insectes Sociaux 53: 136-140
Evison & Hughes (2011) Naturwissenschaften 98: 643-649
Evison & Ratnieks (2007) Ecological Entomology 32: 451-454
Holman et al. (2011) Molecular Ecology 20: 5092-5102
Mueller et al. (2008) Evolution 62(11): 2894-2912

November 28, 2012

Charity Among Vampires

Common Name: The Vampire Bat

A.K.A.: Subfamily Desmodontinae

Vital Stats:

Subfamily contains three species; the common vampire bat (Desmodus rotundus), the hairy-legged vampire bat (Diphylla ecaudata), and the white-winged vampire bat (Diaemus youngi)
All three feed only on blood, a phenomenon known as hematophagy
The common vampire bat feeds primarily on mammals, while the other two species prefer avian blood
Can live up to 20 years in captivity

Found: Throughout Mexico, Central America, and all but the most southern reaches of South America

It Does What?!

Several years ago while on a botanical expedition in the rainforests of South America, I woke one morning to find that one of the other team members, still fast asleep in his hammock, had – apparently – been stabbed in the shoulder during the night. A surprising amount of blood had run down his arm, and yet he snored peacefully away. What the hell had happened to this guy, and was he the world’s deepest sleeper, or what?

Nope. Turns out he had just unwittingly provided a good meal for Desmodus rotundus… the common vampire bat.

As horrifying as it may seem to have flying vermin drinking your blood whilst you sleep, it’s really not as bad as pop culture would have us believe. The bats are more scavenger than predator. To begin with, they prefer stealth and guile to any kind of open attack. Sleeping animals are best, and victims are never approached from the air, Caped Crusader-style. Instead, the bat will land nearby and walk on all-fours over to its prey. From there, it uses heat sensors in its nose (similar to some snakes) to detect where blood vessels pass close to the surface of the skin. In cows, another favourite blood donor of Desmodus, bites are usually just above the hooves or around the ears.

Breakfast of Champions
(Via: National Geographic)

Also contrary to popular belief, the bites are never violent; they’re more like a tiny nick from a very sharp razor- painless, but they tend to bleed a lot. In this case, they’re bleeding a lot because the bat’s saliva contains anticoagulents, preventing the blood from clotting. The bat will lap at the cut with its tongue (no blood-sucking here), transferring saliva into the wound, which will sometimes continue to bleed for hours afterward.

An entire feeding session takes the bat only about 20 minutes, during which time it can consume up to half its own weight in blood. How is this possible? Vampire bats have an amazingly efficient excretory system; the plasma (liquid) portion of the blood is immediately absorbed and passed through the kidneys. Within minutes of beginning to feed, the vampire starts to pee at the same time, and continues to do so until its meal has been reduced to a manageable volume. (Did they leave this part out of the Twilight movies?)

Creepy as these little beasts may seem, they have a surprisingly enlightened social structure. Vampire bats have been cited by animal behaviourists as one of the few examples of reciprocal altruism (“tit for tat”) in nature. You see, the vampire lifestyle is a bit precarious- a bat will die if it fails to feed for two successive nights. As a lifesaving measure, a bat in such dire straits will actually beg another bat for food. The other bat will then regurgitate some of its meal – just enough to make do – into its hungry neighbour’s mouth. Impressively, the bats even keep score. A hungry animal will turn preferentially to a bat it has helped out in the past, and cheaters are recognised and allowed to starve.

“Okay, what do we learn to imitate next?”
(Via: conservationcentre.org)

Far from being mindless, aggressive little monsters, vampire bats are altruistic, intelligent creatures. How intelligent? Researchers who housed a vampire bat with a hen observed the bat to mimic the behaviour of a chick so effectively that the hen settled down on top of the bat as she would to keep a baby warm. The bat then nicked her on the stomach and drank her blood while she tried to mother it.

Now that’s just creepy.

[Fun Fact: Vampire bats listen to the rhythm of an animal’s breathing to determine whether or not it’s asleep. They prefer to return to a victim they’ve had previous success with, and evidence suggests that they can identify individual humans by their breathing noises in the same way that we recognise individuals by their voices.]

[Also: The common vampire bat can jump up to three feet off the ground to reach large prey.]

Says Who?

Groger & Wiegrebe (2006) BMC Biology 4:18
Lee et al. (2012) PloS ONE 7(8): e42466
Schutt (2008) Natural History, November Issue, pg.22

Become a donor today!
(Via: Vampire Legends)

November 21, 2012

Necessity is the Mother of Invention, or, How to Eat Like a Shrike

arthur-morris-loggerhead-shrike-w-texas-horned-lizard-toad-_h2d0892 — (By: Arthur Morris, Via: Livebooks Blog)

Common Name: The Shrike

A.K.A.: Family Laniidae

Vital Stats:

Family consists of three genera and around 30 species
Shrikes range in size from 17cm (6.5”) up to 50cm (20”) long
Feathers may be black and white, cream, grey, or brown

Found: Various species found in North America, Southern Africa, and Eurasia

It Does What?!

Sometimes a creature aspires to a spot a little higher on the food chain, but doesn’t quite have all the equipment to get there. Behold the shrike, the bird that wishes it were a raptor. Like birds of prey, shrikes have strong, hooked beaks, sharp eyes, and an appetite for meat, but they’re missing a couple of important features. First, and most important… no talons. Shrikes can’t grab a victim and tear it into pieces like a hawk or falcon could. And second, no crop (a sort of internal storage pouch), so they can’t eat a large quantity of meat in a single sitting.

Not to be deterred by their anatomical shortcomings, these inventive go-getters have come up with a single solution to both problems. Two birds with one stone, if you will. After dispatching their prey with a quick beak to the back of the neck, shrikes will carry the carcass to a nearby shrub and actually impale it on a short branch or thorn. Aside from looking incredibly badass, this serves to anchor the body in one place, allowing the shrike to use its beak to rip the meat into pieces. What’s more, the bird can just leave its leftovers hanging there for later, like the meat locker at a butcher shop. [Wondering what that looks like? Here’s a video, set to appropriately ominous music.]

Wildlife-M Yaskowich, courtesy of Nature Saskatchewan-Frog impaled on barbed wire fence by Loggerhead Shrike-June 27 2011-3 — And now they’re learning to use human technology…
(Via: Nature Saskatchewan)

What kind of prey are we talking about here? Anything from small insects right up to mice, frogs, lizards, and other birds. There’s even a record of one killing and impaling a good-sized bat. Impressively, shrikes have also hit on the value of ageing their food – one species hunts the toxic lubber grasshopper of the southern United States. The dead grasshoppers are then left hanging for several days to let the poison degrade before being eaten. Clever birds.

Shrikes are monogamous and share in parenting duties; when the female is sitting on eggs, it’s the male’s job to go out and kill something nutritious for two. Of course, this makes selecting a good hunter an important task for females during mate selection. When a single male wants to advertise his skills, he makes a conspicuous display of his biggest, most impressive kills for any prospective ladies. Once he’s gotten one’s attention, he performs a mating dance that mimics the action of impaling prey on branches and then feeds her from his assortment of carcasses. (Be sure to include this point next time you’re explaining ‘the birds and the bees’ to someone.)

449px-Shrike_prey_lizard — The owner of this lizard is probably off getting lucky.
(Via: Wikimedia Commons)

I guess when you have only one major skill, you want to make the most of it, because aside from eating and attracting mates, shrikes also use their impaling trick for communication. Bonded pairs are territorial and will defend their terrain from others of their species. In a sort of macabre message to would-be trespassers, the couple will mount their kills around the borders of their land, perhaps in an effort to show others what could become of them if push came to shove. (Did I mention these things actually have a comic book monster named for them? Eat your heart out, Batman.) Unfortunately for them, researchers note that this action often resulted in the prey being snatched by opportunistic passers-by and having to be replaced. It’s so hard to look murderous when everybody keeps stealing your victims…

[Fun Fact: Shrikes with young chicks will often eat only the head of their prey, saving the bodies for the kids. ‘Cause that’s just good parenting.]

Says Who?

Keynan & Yosef (2010) Behavioural Processes 85: 47-51
Sarkozi & Brooks (2003) Southwestern Naturalist 48(2): 301-303
Smith (1973) Behaviour 44(1/2): 113-141
Yosef & Pinshow (2005) Behavioural Processes 69: 363-367

loggerhead-shrike — You’re next.
(Via: Tough Little Birds)

November 14, 2012

The Cost of Eighty Million Years in Paradise

Common Name: The Kakapo, The Owl Parrot

A.K.A.: Strigops habroptila

Vital Stats:

Males can grow up to 60cm (24”) long and weigh up to 4kg (8.8lbs.)
Average life expectancy of a healthy kakapo is 95 years
Breeding begins around age 9; females lay 1-3 eggs per clutch
Main mammalian predators are rats, cats, ferrets, and weasels

Found: Traditionally, across large areas of both major islands of New Zealand; today, mostly on small, protected island reserves nearby

It Does What?!

Strange things happen when you leave a few species alone on a distant island for a few million years. Places like New Zealand, Australia, Madagascar, and Hawaii are (or were) full of plants and animals that seem alien compared to rest-of-the-world standards. This is often due to a set of conditions and evolutionary challenges unlike those seen on the continent. Life on New Zealand is particularly interesting, having been heavily shaped by the fact that the only terrestrial mammals there are bats. Every animal that evolved there did so without the pressure of having to avoid toothy predators stalking them through the forest. Ever wonder what birds would be like without anything on the ground trying to kill them?

kakapo-1 — “I’m just big boned, okay?”
(Via: Gothic Atheist)

If so, meet the kakapo, the world’s largest, fattest parrot. And the only one that can’t fly. Isolated in New Zealand when the islands separated from the continent over eighty million years ago, the native parrots eventually lost their strong flight muscles and stiff, rigid wing feathers, trading them for greater size and the ability to store a half inch thick layer of fat under their skin to sustain them in lean times. This change also slowed their metabolism, resulting in their being one of the longest-lived birds out there, with a maximum recorded age of 120 years. Slothlike, these peaceful, nocturnal creatures spend most of their waking hours climbing (yes, climbing) from tree to tree, eating fruit and foliage. Unlike sloths, however, they can take a quicker route down, simply leaping from the tree and spreading their stumpy wings in what’s probably a very amusing imitation of a parachute. Unsurprisingly, they’ve developed quite strong legs, and can cover distances of several kilometres at a jog.

The most fascinating aspect of the kakapo lifestyle, though, has to be its mating routine. Unlike most parrots, kakapos aren’t monogamous and don’t share parenting duties. Every three to six years, when fruit crops are particularly good, male kakapos will stake out a small territory on high ground, fighting with other males for the best spots. The “best spots” in this case being those with the best acoustic qualities, such as those backed by a rock wall which can reflect sound outward over the land. Having obtained his mating area, he will construct a series of pristine paths leading up to it (for the ladies), as well as a large bowl-shaped depression in the earth, which acts as an amplifier. Kakapo-sound-system completed, he’s ready to get down to business. The male stands in his bowl, inflates a sac in his chest, and emits a series of eerie, low frequency booms, like distant cannons, loud enough to be heard several kilometres away. He continues to do this, all night, every night, for up to four months, losing up to half his body weight in the process. The female kakapo has it somewhat easier. She simply approaches the emitter of her favourite booms, he performs a short dance routine for her, she gets what she came for, then walks on home to lay her eggs.

kakapo10 — “I could hide better if you two would quit staring.”
(Via: Pour L’animal)

Before the colonisation of New Zealand, the islands were reportedly teeming with these birds, so successfully specialised were they for their unusual environment. Their only natural predators were birds of prey, from which they hid by freezing and blending into the surrounding greenery. Sadly, specialisation is often a one-way street that you can’t back out of if your environment suddenly changes. The features that made the defenseless kakapos good at avoiding avian predators (like their tendency to freeze), made them terrible at avoiding the carnivorous mammals, such as cats, that came with colonisation. Despite having powerful legs with large claws, the birds seem unaware that they can be used as weapons. Worse, their natural curiosity and lack of fear in approaching humans often landed them on both Maori and European dinner tables.

Enormous efforts have been made over the last century to prevent these big, gentle birds from going extinct. As of this year, there are still only 126 known to exist (each with its own name and radio transmitter), but they are a slowly expanding population, thanks to their relocation to three protected, largely predator-free islands. Expectant mothers even have their own nest watchers, who sneak in to cover the nests with electric blankets while mom pops out for a bite. Free babysitting- seems like the least we can do.

nz_south_04_mc — “How do YOU like it?!”
(Via: BBC’s Last Chance to See)

[Fun Fact: Conservationists have had to scale back on the supplemental food they had been giving the kakapos during mating season. It turns out a well-fed kakapo will produce mostly male chicks. Not what you need when you’re trying to rebuild a population.]

[Also: Kakapos use their fine facial feathers like whiskers, walking with their faces near the ground to sense the terrain.]

Says Who?

Douglas Adams & Mark Carwardine (1990) Last Chance to See. Pan Books, London [This is a fantastic book. Highly recommended.]
Grzelewski (2002) Smithsonian Magazine, October Issue
Sutherland (2002) Nature 419: 265-266

October 31, 2012

Nights of the Living Dead… Further Horrors of the Insect World

TarantulaHawk-large3-550x420 — (By: Paul Nylander Via: The Tucson Citizen)

Common Name: The Tarantula Hawk

A.K.A.: Genera Pepsis and Hemipepsis

Vital Stats:

The two genera make up Tribe Pepsini in Family Pompilidae
Grow up to 5cm (2”) long
Stingers are up to 7mm (1/3”) long
Quite long lived for wasps, with lifespans of more than a year
Adults feed primarily on milkweed nectar

Found: Across much of the tropics and southern hemisphere

It Does What?!

Happy Halloween, readers! Today’s the day when we’re surrounded by images of zombies, witches, ghosts, and spiders- all creatures meant to scare us on some level. Of course, only one of these things is real. And spiders truly are a scary thing for many people. For all you arachnophobes out there who are feeling vaguely uncomfortable about the preponderance of fake spiders out there today, did you ever wonder what the spiders fear? What keeps tarantulas, the biggest, scariest arachnids of them all, awake at night? Tarantula hawks, that’s what. If spiders had Halloween, this is what they would dress up as.

Like any good mother, the female tarantula hawk wants to ensure that her baby has all the food it requires to grow up into a healthy adult wasp. Rather than bag a large piece of prey and have it spoil by the time her egg hatches, she has developed an ingenious system of keeping meat fresh.

Spying a tarantula from the air, she will attack, injecting the spider with her venom as it struggles to bite her. A particularly hard and slippery exoskeleton renders this counterattack ineffective; the fangs simply slip off her. Before long, the tarantula has succumbed to her venom and is alive, but completely paralysed. Once the prey has been neutralised, she sets out over land, dragging the spider up to 100m (quite a long way, considering the scale involved) back to the site of a burrow she has dug out. Here, our mom-to-be lays a single egg on the helpless spider’s abdomen, then proceeds to immure it in the burrow.

Guyana Photo — A hundred metres starts to look like a very long trip.
(By: Erin Zimmerman, taken during my field work in Guyana)

But this is only the beginning of the horror for the paralysed spider. Soon after, the egg hatches, and the hungry larva tunnels directly into the spider’s flesh, eating as it goes. The larva instinctively knows to avoid the tarantula’s vital organs as it eats, thereby keeping the prey alive for as long as possible. After several weeks of chowing down, the larva finishes off the job and emerges from the spider’s body, having now matured into a wasp. It then simply unseals the burrow and flies away, leaving the late tarantula in its ready-made grave.

Wondering what happens when a person gets stung by one of these? It’s an interesting question, because the answer is both “a lot” and “not much”. You see, the paralytic agent in the venom only works on invertebrates, and won’t actually do any real damage to human tissue. Before you go trying to catch one, though, know that, in terms of immediate reaction, tarantula hawks are considered to have the single most painful insect sting in the world. It’s best described by an entomologist who has actually experienced such a sting:

“Advice I have given in speaking engagements was to ‘lay down and scream’. The reasoning being that the pain is so debilitating and excruciating that the victim is at risk of further injury by tripping in a hole or over an object in the path and falling onto a cactus or into a barbed wire fence. Such is the pain, that few, if any, can maintain normal coordination or cognitive control to prevent accidental injury. Screaming is a satisfying expression that helps reduce attention to the pain of the sting itself.” [Schmidt 2004]

In short… don’t touch these.

A few words now on just how frighteningly well-adapted this wasp is. Not only is it covered in armour and full of incredibly painful venom, but at roughly the size of your little finger, it’s one of the largest wasps out there, and more of a fight than most insectivores want to deal with. It is essentially without predators. And lest any potential enemies forget why they’re not touching it, the tarantula hawk has both a distinct colour and a characteristic odour, meant to remind aggressors of the pain associated with any previous run-ins. Researchers have described tarantula hawks as being “among the best defended animals on earth” [Schmidt 2004]. And because success always spawns imitation, there are now several other creatures mimicking the appearance of the female tarantula hawk as a form of protection, including the more-or-less defenceless males of the same species.

So the next time you shudder at the thought of a tarantula stalking you in the wild, stop and remember what might be stalking it.

[Fun Fact: Despite its phenomenal pain-inducing qualities, tarantula hawk venom is only about 5% as lethal as honeybee venom, based on studies by people who inject white mice with horrible things for a living.]

Says Who?

Alcock & Kemp (2006) Ethology 112: 691-698
Kurczewski (2010) Northeastern Naturalist 17(1): 115-124
Schmidt (2004) Journal of the Kansas Entomological Society 77(4): 402-413
Schoeters et al. (1997) Canadian Journal of Zoology 75: 1014-1019

October 24, 2012

Life in Slow Motion: the Three-Toed Sloth

MC_Drei-Finger-Faultier — (Via: Wikimedia Commons)

Common Name: Three-Toed Sloth

A.K.A.: Genus Bradypus

Vital Stats:

There are four species of three-toed sloth: brown-throated, pale-throated, maned, and pygmy
Critically endangered pygmy sloths are thought to number only around 300
Average body length of around 45cm (18”)
Two-toed sloths have a similar arboreal lifestyle, but belong to a different family entirely

Found: Rainforests of Central and northern South America

It Does What?!

Evolution, we’re sometimes led to believe, is an ongoing pressure to produce the fastest, strongest, and most cunning creatures possible, in an effort to improve each species’ fitness in its environment. But what if a niche existed in which being well-adapted simply meant holding very still and taking it easy?

Oh, to be a sloth.

Three-toed sloths are small-dog-sized mammals which live in the rainforest canopy and survive on a diet of leaves. Rather than sitting atop the branches and risking a fall if they lose their balance, sloths use their large claws to cling to branches from below, even sleeping in this position. Leaves aren’t exactly the most nutritious food, calorie-wise, so they conserve energy by moving v e r y s l o w l y, reaching top speeds of around 240m (787’) per hour. Over the course of an entire day, this works out to only 3 or 4 different trees, at most. And this is in their natural environment of the canopy; on the ground, sloths are practically helpless. Unable to even stand due to their minimal musculature, they must simply pull themselves along the earth if a break in the canopy necessitates a ground crossing. [Check out this video of a sloth crossing a road in Costa Rica with the help of some protective humans… your heart will break for the poor thing.]

9gbn1d94yyb72eqlyt — When vegetation starts growing on you, it’s time to get some exercise.
(By: Maureen Sokolovsky, Via: travelhotnews.com)

This same natural… well, sloth, is what helps them to avoid their main predators, which include jaguars, anacondas, and birds of prey. Hanging motionless upside down, sloths can appear to be just another bunch of leaves. Aiding this illusion is the fact that many sloths are, in fact, somewhat green. This is due to a thin layer of algae which grows over their fur, each hair of which is specially shaped to encourage microbe growth. And the algae aren’t the only ones treating sloths as if they were inanimate objects; a species of moth known as the “sloth moth” also lives in their fur, while a small bird, the yellow-headed caracara, forages for its food there. Basically, other animals consider these guys to be just another piece of the landscape.

The energy-saving ways of the sloth really can’t be overstated- they don’t even maintain a normal mammalian body temperature, but one several degrees lower, necessitating a lot of basking in warm places to keep them comfortable. And the insides don’t go any faster than the outside; sloths only go to the bathroom around once per week, laboriously making their way down to ground level to use a special pit they’ve dug for themselves there. [Here’s another great video of Sir David Attenborough telling us about sloth toilet habits.]

three-toed-sloth-with-child — The Zen-like smile of the world’s most chilled-out creature.
(By: Karla Aparicio, Via: Smithsonian Tropical Research Institute)

But surely the pace of things picks up a bit when it’s time to make baby sloths, right? Apparently not. Reports by researchers indicate that mating in sloths involves about twenty minutes of hanging nearly motionless in a tree together, followed by several days of hanging out a few metres apart, doing nothing and probably avoiding eye contact, before both decide it’s time to take off. Baby sloths are born singly, or occasionally as twins, and spend the first nine months of their life clinging to their mothers’ front, first nursing, and then licking chewed leaves from her mouth, before finally setting out on their own.

And that’s pretty much the life of a sloth. With a lifespan as long as thirty years, it’s a good thing they don’t get bored. Or maybe they do… giving us the answer to the question, ‘Why did the sloth cross the road?’

[Fun Fact: With nine cervical vertebrae, compared to only seven in most mammals, sloths have a huge amount of flexibility in their necks, with a rotation similar to that of owls.]

Says Who?

Bezerra et al. (2008) Journal of Ethology 26: 175-178
Dias et al. (2009) Journal of Ethology 27: 97-103
Raines (2005) Zoo Biology 24: 557-568
Taube et al. (2001) Mammal Review 31(3):173-188
Bye!