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Charity Among Vampires

(Via: National Geographic)

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

(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.]

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.)

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
You’re next.
(Via: Tough Little Birds)
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The Cost of Eighty Million Years in Paradise

(Via: The Life of Animals)

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?

“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.

“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.

“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
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Pitcher Plants: Sweet Temptation and the Slippery Slope

(Via: Wikimedia Commons)

Common Name: The Asian Pitcher Plant

A.K.A.: Genus Nepenthes

Vital Stats:

  • Over 130 species in the genus
  • The vast majority of species have extremely narrow ranges of only a single island or small island group, and are considered threatened
  • Most recently discovered (2007) was Nepenthes attenboroughii, named for Sir David Attenborough, who is fond of pitcher plants

Found: Mountainous regions of Southeast Asia, Oceania, and Madagascar

It Does What?!

Plants have evolved a variety of different ways to deal with growing in nutrient-poor soils. Some become parasitic, some develop close symbiotic relationships with bacteria or fungi, and some of them… well, some of them just start eating animals.

Lizard: makes a nice, light snack.
(Via: Wikimedia Commons)

One group of plants that went this route are the Asian pitcher plants (not to be confused with the not-closely-related New World pitcher plants, which tend to have tall, flute-like pitchers). These smallish, climbing plants use highly modified leaves to form what are essentially external stomachs, complete with the plant’s own digestive fluid. These pitchers, which vary in size from one species to the next, have extremely slick, waxy inner walls. When visitors come to eat the nectar produced on the lid (or “operculum”) of the trap, they lose their footing and fall into the liquid below.

That liquid is actually a pretty complex mixture; it’s divided into two phases, like oil and water. The upper portion is mostly rainwater, but has been laced with a compound that makes it more viscous, preventing winged insects from just flying away, as they could from pure water. The trap’s lid actually functions to prevent too much rainwater from getting inside and diluting the fluid too much. The lower portion of the liquid is a digestive acid capable of breaking down flesh into useable molecules (particularly nitrogen and phosphorous), much like our own stomach acid. Analogous to our intestines, the lower inside surface of the pitcher is covered with special glands that absorb suspended nutrients.

Most of what gets caught in pitcher plants is about what you’d expect- winged insects, spiders, beetles, small scorpions. But occasionally, some larger animals find their way in. Things that should have known better, like frogs, lizards, and even birds. Arguably, these plants are doing evolution a favour by taking out any bird dumb enough to fly into its own watery grave. And yes, to answer your next question- they can eat rats, but only a single species has been documented to do this. Nepenthes rajah, the largest of all pitcher plants, has pitchers which grow to a height of nearly half a metre (1.6’) and hold up to three and a half litres (1gal.) of fluid, most of which is digestive juice.

Interestingly, pitcher plants have formed symbiotic relationships with several of the same types of creatures that it otherwise preys on. Nepenthes lowii, for example, provides nectar to a tree shrew. Instead of falling in and being digested, the shrew treats the pitcher as its personal toilet, thereby providing the plant with most of the nutrition it requires.

In one end and out the other.
(Via: Wikimedia Commons)

Other species form alliances with groups of carpenter ants. In exchange for a steady supply of nectar and a place to live- in this case a hollow tendril- the ants basically act as the plant’s evil henchmen (apparently a specialty of ants). When prey that is too large to be easily digested falls into the trap, the ants remove it, rip it to shreds, and then throw the bits back in again.

How’s that for a brilliant piece of evolution? Not only did these plants grow an external stomach… they get ants to chew their food for them.

[Fun Fact: Some pitcher plants primarily survive by digesting leaves that fall from trees into their traps – the ‘vegetarians’ of the carnivorous plant world.]

Says Who?

  • Bonhomme et al. (2011) Journal of Tropical Ecology 27: 15-24
  • Clarke et al. (2009) Biology Letters 5: 632-635
  • Krol et al. (2012) Annals of Botany 109: 47-64
  • Robinson et al. (2009) Botanical Journal of the Linnean Society 159: 195-202
  • Wells et al. (2011) Journal of Tropical Ecology 27(4): 347-353
So big it makes them vaguely uncomfortable.
(Via: Wikimedia Commons)
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Nights of the Living Dead… Further Horrors of the Insect World

(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.

A creature that can kill small rodents being outmatched by a nectar-sipping insect. Sad.
(Via: Wikimedia Commons)

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.

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
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Life in Slow Motion: the Three-Toed Sloth

(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.]

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.]

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!
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The Stench of Death, brought to you by the Forests of Sumatra

(Via: The Parasitic Plant Connection)

Common Name: Giant Rafflesia

A.K.A.: Rafflesia arnoldii

Vital Stats:

  • One of about 28 species of Rafflesia, all parasites native to southeast Asia
  • Dioecious: produces male and female flowers on separate plants
  • Flowers last only a few days

Found: In the rainforests of Sumatra, Western Indonesia

It Does What?!

In my very first post here on Questionable Evolution, I discussed the Titan Arum, a.k.a. Corpse Plant, known for its pungent aroma and generally phallic appearance. This rare oddity is confined to the ever-shrinking rainforests of the western Indonesian island of Sumatra. Now meet its neighbour and fellow rotting flesh imitator, the Giant Rafflesia. Like the Titan Arum, this species is found only in the Sumatran rainforest and uses its odour to attract carrion flies for pollination. (With all the plants pretending to be dead animals on this island, it’s a wonder the flies ever actually find themselves any real carcasses.)

How big?  THAT big.
(With Mr. Troy Davis, Via: The Parasitic Plant Connection)

Rafflesia’s claim to fame in the plant world is that it produces the largest flower on Earth. A single bloom from Rafflesia arnoldii can reach a diameter of 1m (3.3’) and a mass of up to 7kg (15lbs.). In other words, one flower weighs about as much as your overweight cat. Impressive, sure, but what’s more interesting about this plant is that the flower’s the only part of it you’re ever likely to see.

Much like dodder, rafflesia is a holoparasite, depending entirely on a host plant (in this case, a vine of genus Tetrastigma, part of the grape family) for its water and nutrients. Unlike dodder, however, rafflesia doesn’t grow up and over its victim, eventually smothering it- no, this plant grows inside its host. Over the course of its evolution, the leaves, roots, and stems of rafflesia have been reduced to nothing but miniscule threads that grow, fungus-like, through the intercellular spaces of another plant, absorbing whatever they require. The giant flower arises directly from the roots or stem of the host vine, pushed out through the host’s tissues. Think chestbursters from Alien. Beyond the juvenile phase when a new seedling searches for its host, this is the only part of rafflesia that will ever see the light of day.

Flowering Time!!

Interestingly, botanists have found that rafflesia’s giant flowers evolved over a very short period of time (relatively speaking), with flower diameter increases of, on average, 20cm per million years. Blindingly fast, as plant evolution goes. The reason for this, they speculate, may have been a preference on the part of certain carrion flies to feed on larger animal carcasses. The range of flower sizes seen in different species of genus Rafflesia probably functions to attract different sets of fly species with varying tastes – some want wee little dead mice, some want dead rhinoceros, judging from the size of these things.

Plants: give ‘em a few million years, and they can mimic almost anything.

Says Who?

  • Barkman et al. (2008) Current Biology 18: 1508-1513
  • Beaman et al. (1988) American Journal of Botany 75(8): 1148-1162
  • Patifino et al. (2002) New Phytologist 154: 429-437
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Theft: Better Than Sex (Bdelloid Rotifers)

(Via: Wikimedia Commons, Image by: Diego Fontaneto)

Common Name: Bdelloid Rotifers

A.K.A.: Families of Order Bdelloida

Vital Stats:

  • Around 360 asexual species
  • All species likely descended from the same ancestor
  • Common ancestor lived 50-100 million years ago

Found: Fresh water bodies of any size, on every continent, including Antarctica

It Does What?!

Here’s a creature that truly exhibits questionable evolution- as in, the kind that tends to make you go extinct in a hurry. Bdelloid rotifers (the ‘B’ is silent) are microscopic animals found in all kinds of moist, freshwater habitats- puddles, ponds, mossy areas; you name it, they’re probably there. What’s so unusual about these guys is that they’re entirely asexual, and have been for a very, very long time. In fact, bdelloid rotifers are all female, a consequence of how they reproduce.

Don’t drink pond water.
(Via: TopNews.in)

Now, asexual reproduction isn’t so uncommon. If you look at a field of dandelions, chances are, they’re all clones derived from asexual reproduction in a single common ancestor- no second parent needed. Even such advanced creatures as komodo dragons do this periodically- a baby dragon is formed from an unfertilized egg inside the mother. What differentiates bdelloid rotifers from other asexual reproducers is that it’s all they’ve done for the last 50 million years or more. Outside of our friends the rotifers, a species must either have sex from time to time, or face extinction.

Why? Because sex solves two major problems in life (your individual results may vary..). First, it weeds out errors which tend to accumulate in DNA over time. Unlike asexuals, which pass on a copy of a copy of a copy (etc.) of their genes, sperm and egg cells contain DNA which has been mixed and matched via a process called meiosis. The gist of this is that an organism can procreate without necessarily passing on any genetic errors it may have to the next generation. Second, this same process of mixing and matching creates new combinations of DNA sequences, which in turn create the natural variation between individuals that evolution can select for or against.

Not the most visually interesting creatures, these rotifers…
(Via: Natural History Museum)

For example, a genetic combination which caused a polar bear to be born with a white nose would be selected for, since it would make a more effective camouflage for hunting. On the other hand, a combination which gave polar bears big black patches on their fur would be selected against, because they’d have a harder time hunting and would therefore starve more often. Asexuals, however, can neither quickly generate useful new combinations, nor purge their populations of harmful mutations.

So on the surface, it comes as a surprise to biologists that bdelloid rotifers have been able to survive for such an epic amount of time with no sex (in addition to the absence of males, genetic tests are able to show that meiosis hasn’t occurred). However, the rotifers have two impressive ways of dealing with this. First, when times get tough, they already have a pretty good defence mechanism worked out- they just dry up. The rotifer dehydrates itself and forms a dormant cyst in which it can remain in this state until conditions improve. This is called anhydrobiosis.

…but what do you expect from sexless pond scum?
(Via: SpaceTravel.com)

Second, and more importantly, they steal genes. This is the true secret to the successful asexual lifestyle. When a rotifer emerges from dormancy and needs to patch itself up, it’s actually able to incorporate random genetic material from its environment into its own genome. A nearby bacterium, some fungus, a passing bit of rotting leaf? All fair game, apparently. Researchers have found genes from each of these three groups in the rotifer genome. Incorporating these new bits of sequence seems to give rotifers the variation they need to develop new traits and stay off the evolutionary chopping block. In fact, given the success of the bdelloid rotifers – they’ve evolved into over 300 species since giving up sex – and the ease of asexual procreation – no need to find a partner – an argument could be made that when it comes to new genes, theft really is better than sex.

Says Who?

  • Gladyshev et al. (2008) Science 320(5880): 1210-1213
  • Harvard Magazine, Nov.-Dec. 2000 “An Evolutionary Scandal”
  • Welch & Meselson (2000) Science 288(5469): 1211-1215
  • Wilson & Sherman (2010) Science 327(5965): 574-576
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EVOLUTION TAG TEAM, Part 3: Coral Polyps & the Garden Within

The third in an ongoing series of biology’s greatest duos. (Check out Parts One and Two)

(Via: Wikimedia Commons)

Common Name: Coral Polyps

  • A.K.A.: Class Anthozoa, Subclass Hexacorallia

Common Name: Coral Algae

  • A.K.A.: Genus Symbiodinium

Vital Stats:

  • Polyps grow to a length of only a few centimetres, depending on species
  • Coral can grow outward at a rate of up to 10cm (4”) per year
  • The Great Barrier Reef stretches over 2000km (1243 mi) and can be seen from space

Found: Various coastal areas; largest reefs surrounding Australia, Oceania, and the Caribbean

It Does What?!

If you’ve ever been told that coral reefs are alive, then looked at one and felt a bit sceptical that this chuck of colourful rock could be a living thing… well, good for you, because you’re actually mostly right. The vast majority of the volume of a coral reef is, in fact, nonliving inorganic mineral (calcium carbonate, specifically). The amazing thing about coral isn’t so much what it’s made of, but what’s going on on the surface. You see, that oddly-shaped, porous rock is actually a communal exoskeleton produced and excreted over time by hundreds of thousands of polyps living in the tiny, cup-shaped depressions on the surface.

“Breaded, with a side of chips, please.”
(Via: Wikimedia Commons)

Looking like tiny jellyfish (and belonging to the same phylum), the polyps hide in the stony sanctuary they’ve made, letting only their tentacles project. These tentacles are tipped with stinging cells which can inject a powerful venom into any prey foolish enough to swim within reach. This prey can range in size from microscopic plankton to small fish. That’s right, coral eats fish. Watch where you stick your toes.

So where does the ‘duo’ part come in? Despite their ability to snatch passing sea creatures and eat them, coral polyps actually get only a small part of their caloric intake this way. Impressively, these guys managed to find a diet that requires even less effort than just reaching out and grabbing stuff. Who needs movement when you can just photosynthesize, like plants do? The polyps have developed a symbiosis with a type of single-celled alga (called zooxanthellae) that allows them to do just that.

The algae start out as free-living cells drifting through the water. They are eaten by the coral polyp, but instead of being digested, they are able to enter the cells lining its digestive tract. Since the polyps are transparent to begin with, all they have to do is expose their bodies to sunlight in order to allow the algae to produce sugars by photosynthesis (this is why reefs form in relatively shallow waters). The majority of the sugars made by the symbiont are then absorbed by the polyp.

And what do the algae get out of this arrangement? A couple of things. First, they get a safe place to live, and won’t get eaten by something that can digest them. Second, they get nutrients, in the form of carbon dioxide and nitrogen compounds, both natural waste products of the polyp’s metabolism. Still, sometimes as much as 30% of the cells in a polyp are algal cells, and this puts a stain on the host’s physiology.

“I’ve just got a lot going on right now.”
(Via: Wikimedia Commons)

Maybe you’ve heard of “coral bleaching” as one of the symptoms of pollution around reefs. Bleaching happens when additional stresses (like pollution) get to be a bit too much for the polyps to handle. They can’t change the water purity, so instead, they offload the stressor they can control- the algae. Getting rid of the photosynthetic cells also gets rid of much of the characteristic colour of the reef, hence the term ‘bleaching’. In the short term, this is a smart move. It increases the polyp’s chance of survival during brief crises, and new algae can always be taken on when the host is ready. The real problems start when the environmental stress persists, and the polyp never takes on new algae. Eventually, it can’t sustain itself and dies, as those in a tenth of the world’s reefs already have. At least there’s still hope for these areas; if conditions improve, new colonies can be formed using the old reef as a foundation. The Great Barrier Reef, for example, is considered to be between 6000 and 8000 years old. However, the modern structure has developed atop an older, dead reef system, thought to be over half a million years old. Time enough for us to clean up our act, maybe.

[Fun Fact: Coral polyps only reproduce sexually to start new colonies. Within a single piece of coral, all the polyps are genetically identical clones, produced by polyps dividing in half and then re-growing their lost tissues.]

Says Who?

  • CoRIS- Coral Reef Information System
  • Fransolet et al. (2012) Journal of Experimental Marine Biology and Ecology 420-421:1-7
  • Piper (2007) Extraordinary Animals. Greenwood Press: Westport, Connecticut.
  • Wooldridge (2010) BioEssays 32(7):615-625

    The little-known “Lady Gaga Coral”
    (Via: Wikimedia Commons)
Posted on

The Plant That Time Forgot (Welwitschia mirabilis)

(Via: Wikimedia Commons)

Common Name: Welwitschia mirabilis

A.K.A.: Welwitschia

Vital Stats:

  • Welwitschia is a gymnosperm, like pines or firs, and thus reproduces via male and female cones
  • Considered a “living fossil”
  • Named after one of its discoverers, Austrian botanist Friedrich Welwitsch
  • In mature specimens, the woody stem can grow up to one metre (3.3’) across

Found: In the Namib desert, along the west coast of Namibia and Angola

It Does What?!

Restricted to a tiny, arid swath of African desert, Welwitschia mirabilis represents the last remaining species of a very unusual lineage of plants. Close relatives met with extinction over the aeons, while welwitschia, tucked away in its remote and harsh desert range with little competition, just kept going. The fact that the species is alone, not just in its genus, but also in its family and order (the two ranks above genus in plant systematics), speaks to just how distantly related to any other living plant it is. For the sake of comparison, the Rosales, the order to which roses, apples, and pears belong, contains around 7700 species in 9 families and 260 genera. So original and captivating is welwitschia among plants that it has been the subject of more than 250 scientific articles since it was first described in 1863.

A mere infant. But probably still older than you are.
(Via: Lizworld.com)

So what makes this thing so weird? Well, plants typically have what’s called an apical meristem at the tips of their stems and/or branches. You can think of this as a clump of stem cells that keeps dividing, throwing off new leaves and buds in its wake. If you cut off the apical meristem, the plant must either develop a new one elsewhere, or stop producing new tissue.

In welwitschia, this isn’t the case. At the beginning of the plant’s life, the apical meristem produces just two leaves, and then dies. The plant will never grow another leaf, which is much more surprising when you consider that it may well live for more than a thousand years. How do you get through a millennium with only two leaves?! The answer is, these aren’t ordinary leaves. Uniquely, welwitschia’s two strap-like leaves have a band of meristematic tissue built into their base, which means they can continue to elongate outward indefinitely. The leaves will continue to grow at a rate of around half a millimetre (0.02”) per day for as long as the plant lives. If you’re thinking that this must mean leaves that are several hundred metres long, unfortunately, no, they aren’t. The leaves are abraded away by sand storms and eaten by passing animals. Even in the best case scenario, the cells at the leaf tips have a maximum lifetime of about ten years (still pretty good for a leaf…). What’s more, the leaves tend to get frayed and split over time, and end up looking like a lot more than just two leaves. Despite all the punishment, though, each leaf can reach a length of up to four metres (13’), giving a mature welwitschia a width of up to eight metres (26’) across.

Welwitschia’s answer to the pinecone.
(Image by Friedrich A. Lohmuller)

As you might expect from a long-lived relic of the past, there aren’t a lot of these plants around. For once, this has less to do with human disturbance than natural circumstances. Over millions of years, the range where welwitschia grows has dried out considerably, and in fact continues to get drier even now. Today, the plant relies largely on fog to meet its water needs, restricting its range to a thin strip of desert coastline where fogs occur regularly. Unlike cactuses or succulents, welwitschia has never evolved the ability to store water. Also problematic is a fungus, Aspergillus niger, which frequently infects and destroys germinating seeds. These factors together can mean that a welwitschia colony can sometimes go many years without successfully reproducing.

And of course, no threatened species would be complete without some human interference. In recent decades, unscrupulous collectors have removed plants from already small breeding populations, making it even more difficult to sustain their numbers. Interestingly, it’s noted in Wikipedia that plants in Angola are actually better protected from collecting than those in Namibia due to the higher concentration of landmines there.

So… landmines: bad for humans, good for endangered plants.

You think you have problems with split ends?
(Via: Natural History Museum)

Says Who?

  • The Gymnosperm Database
  • Dilcher et al. (2005) American Journal of Botany 92(8):1294-1310
  • Henschel & Seely (2000) Plant Ecology 150:7-26
  • Jacobson & Lester (2003) Journal of Heredity 94(3):212-217
  • Rodin (1958) American Journal of Botany 45(2):96-103