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!

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

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

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)

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

Thank a Horseshoe Crab

(Via: reefguide.org)

Common Name: Horseshoe Crab

A.K.A.: Family Limulidae

Vital Stats:

  • Four extant species of horseshoe crab in three genera (Limulus, Carcinoscorpius, and Tachypleus)
  • Females are larger than males, and can reach up to 60cm (24”) long in some species
  • Believed to live between 20 and 40 years

Found: Coastal waters of southeast Asia, Oceania, and eastern North America

It Does What?!

Like the platypus and the lungfish, horseshoe crabs are what biologists refer to as “living fossils,” meaning their basic form has gone essentially unchanged for many millions of years. In the case of horseshoe crabs, fossils as old as 445 million years have been found that are quite similar to the extant species of today.

Despite their common name, the Limulidae aren’t true crabs. They’re arthropods, like crabs, but are actually more closely related to spiders and scorpions. In fact, beneath that tough shell, they do look quite spider-like. If spiders had tails, that is.

Basically a tarantula in combat gear.
(Via: Wikimedia Commons)

Horseshoe crabs live in shallow coastal waters, feeding off worms and molluscs from the ocean floor. They are able to feed in near complete darkness at night due to a remarkable visual system. The creatures have three different types of eyes – compound, median, and rudimentary – located to both sides and to the front of their shell. What’s more, their compound eyes become a million times more sensitive to light at night than they are during the day. Since that’s roughly how much less light they have to work with at night, the crabs are able to see equally well at night and during the day.

Most people who have observed horseshoe crabs know them from their unusual breeding habits. Each spring and early summer, male crabs will search out a mate and attach themselves to the female’s shell using a special modified leg. Then, during the highest tides of the year, usually at night, the females crawl up onto shore by the hundreds, carrying their male cargo. Having picked a spot that’s moist, but not so low as to be washed away with the tide, they dig a nest into the sand and lay their eggs. The attached males get first dibs at fertilising the pre-laid eggs, but must share the task with numerous mate-less onlookers who rush in to get their shot at fatherhood as well (crabs are so uncouth). Since eggs number in the tens of thousands per female, many will probably be successful. Most of these thousands of eggs, however, will become food for migratory birds, who appreciate the extra protein snack on their long journeys. After a month or so, the uneaten eggs will hatch into larvae, which remain on the beach in groups for a couple of weeks before moulting into juvenile horseshoe crabs and finally moving into the water.

Horseshoe crabs, making more horseshoe crabs.
(Via: Wikimedia Commons)

Now you might be thinking, “That’s all well and good, but what can horseshoe crabs do for me?” Well, as it turns out, these creatures are some of the most prolific blood donors on Earth (whether they like it or not). Like our friend Mr. Spock, horseshoe crabs have copper-based blood, rather than the iron-based concoction favoured by humans. They are literally blue-blooded. And instead of white blood cells to fight off infection, they have amebocytes. These amebocytes are so valuable in detecting certain types of bacterial infections in humans that a quart of horseshoe crab blood is worth approximately $15,000 US. Crabs are caught, transported to a lab, and drained of about 30% of their blood before being released. The company behind this 50 million dollar per year industry states that only about 3% of the quarter million crabs die from the procedure annually, while other studies have found the number to be nearer to 15% (read more about it here). Knowing who’s right may become very important, as horseshoe crab populations are declining worldwide, additionally affecting the migratory birds that feed on their eggs. Either way, next time you survive an E. coli infection, thank a horseshoe crab.

No, no… we don’t mind. Really.
(Via: TYWKIWDBI)

[Fun Fact: Horseshoe crabs are thought to be the closest living relative of the extinct trilobite.]

[Also, here’s a cool video of (who else?) Sir David Attenborough explaining the mating habits of horseshoe crabs.]

Says Who?

Ergot: Bringing the Crazy Since 800 A.D.

(Via: The University of Illinois Extension Collection)

Common Name: Ergot, Ergot of Rye

A.K.A.: Claviceps purpurea (and other Claviceps species)

Vital Stats:

  • Around 30-40 species in genus Claviceps, all parasites of various types of grasses
  • Parasitizes rye, barley, and wheat crops in temperate regions
  • Problematic in Africa due to its parasitism of sorghum and millet

Found: Throughout temperate and tropical regions, though historically most problematic in Europe, Africa, and North America

It Does What?!

Disrupts human history and generally scares the hell out of people, to put it mildly. But before we get into that, let’s start with what this stuff is. An ergot infection begins when a microscopic fungal spore lands on the open floret of a grass plant. In northern agricultural areas, rye and, to a lesser extent, barley are particularly susceptible to these spores. Once on the receptive flower, the spore behaves as though it were a pollen grain, growing down the style until it reaches the ovary. At this point, it destroys the ovary and links into the adjoining vascular tissue, where it can parasitize the plant for nutrients.

With plenty of food on tap, the fungus grows into the space that the grain would have otherwise filled. Early on, it forms into a soft, white mass that causes a sugary liquid to drip from the flower. This liquid is filled with spores and is spread to other plants by hungry insects as they fly from flower to flower. Later in the growing season, around the time neighbouring non-parasitized grains are ripening, the fungal mass dries and hardens into a sclerotium (a sort of fungal seed body) that looks a bit like wild rice, and drops to the ground. This sclerotium will sit dormant on the ground until spring, when moisture will cause it to sprout small mushrooms, which produce spores for the new season.

Hint: Wild rice doesn’t do this when you get it wet.
(Via: mycotopia.net)

Still reading? Good. Here’s the interesting part. Let’s say you’re a farmer in the Middles Ages, and the infected plants in question are in your field. Before the ergot sclerotia drop to the ground, they get harvested with the rest of the crop, and end up getting made into bread for you and your family. Well, it turns out those sclerotia are full of a toxic alkaloid called ergotamine, and after eating enough loaves of bread to build the compound up in your systems, you and your nearest and dearest have contracted ergotism. Fed some of that rye to your cows? Now they’ve got it, too!

Ergotism delivers a one-two punch of physical and psychological symptoms. Physically, the alkaloid constricts blood vessels, leading to an intense burning sensation in the arms and legs which can eventually cause gangrene and loss of the entire limb. Some sufferers also develop a persistent ringing in the ears. That’s before the seizures and untimely death set in. Psychologically… well, it makes you crazy. As in, hallucinations and irrational behaviour, which lead many victims to be ostracised by their communities. Ergotism is speculated to have been the cause of the Dancing Mania (not as fun as it sounds) that hit Europe in the Middle Ages. Huge numbers of people were struck by an uncontrollable urge to dance – violently and while screaming – until they collapsed from exhaustion. Did I mention that this stuff is where LSD came from? The drug was originally synthesised from ergotamine, handily delivering all the craziness with none of the gangrenous limb loss.

Nope, nothing suspicious-looking here.
(Via: Wikimedia Commons)

The cure for all this horror? Well, if you got to it early enough, simply not eating any more contaminated grain would cause symptoms to slowly abate. Unfortunately for medieval peasants, who ate a lot of rye and suffered most of history’s outbreaks, the cause of the disease was completely unknown. Weird-looking sclerotia were so common that they were thought to be a natural feature of rye. That old standby, “It’s the wrath of God” actually seemed supported, since sufferers who left the affected area on pilgrimages immediately began to show improvement (hence another term for the disease, ‘Holy Fire’). Sadly, it took the better part of a millennium before someone worked out what was really going on, and major outbreaks occurred right up to the 19th century. Even in the 21st century, minor outbreaks have occurred in developing countries, such as the case in Ethiopia in 2001, caused by infected barley.

Speaking of disrupting human history, some researchers have speculated that an ergotism outbreak caused the strange behaviour that resulted in the Salem witch trials of the late 17th century. Others have disputed this claim, noting, among other points, that ergotism was known and recognisable by this point in history. We may never know for sure.

[For other historical events in which ergotism may have played a role, check out the first reference below.]

[Fun Fact: Due to its action as a vasoconstrictor, ergotamine is now used, in purified form, to treat migraines and post-natal bleeding.]

Says Who?

Randomly Assembled and Surprisingly Dangerous: The Platypus

(Via: National Geographic)

Common Name: The Duck-Billed Platypus

A.K.A.: Ornithorhynchus anatinus

Vital Stats:

  • Only species of Family Ornithorhynchidae
  • Males average 50cm (20”) long, females 43cm (17”)
  • Weigh between 0.7 and 2.4kg (1.5 – 5.3lbs.)
  • Body temperature of 32 degrees Celcius; five degrees lower than placental mammals
  • Live up to 17 years in captivity
  • Eat freshwater crustaceans, worms, and insect larvae

Found: Eastern Australia and Tasmania

It Does What?!

Besides looking like it was assembled from spare parts? We’ve all seen pictures of platypuses (yes, “platypuses”, not “platypi”) before, and everyone knows what total oddities they are: the duck-like bill, the beaver-esque tail, the fact that they lay eggs, despite being mammals; but behind these weird traits lie… even more weird traits! So let’s take a moment to appreciate the lesser-known eccentricities of the platypus, shall we?

First off, these cuddly looking freaks are actually dangerous. Male platypuses have a spur on each hind foot which is filled with a venom powerful enough to kill a large dog. While it isn’t enough to take out a human, it does cause severe, incapacitating pain whose after-effects can last for months. One of only a very few venomous mammals, the male’s venom production increases during the breeding season, suggesting its purpose may lie in competition with other males.

Why your dog and your platypus shouldn’t play together.
(By Jason Edwards, via: How Stuff Works)

And speaking of breeding, reproduction in platypuses isn’t exactly ‘mammal standard’, either. Unlike all other mammals, which have two sex chromosomes (X and Y; XX for females, XY for males, with rare exceptions), the platypus has ten. Talk about evolutionary overkill. A male platypus has the pattern XYXYXYXYXY, while a female has ten Xs. Researchers have found that the actual genetic structure of these sex chromosomes is actually more similar to birds than mammals, although 80% of platypus genes are common to other mammals.

After this alphabet soup of chromosomes arranges itself, up to three fertilised eggs mature in utero for about four weeks; much longer than in most other egg-laying species (in birds, this may be only a day or two). Once laid, the eggs are only about the size of a thumbnail, and hatch in around ten days. While platypuses produce milk, they don’t actually have proper teats to suckle their babies- the fluid is released from pores in the skin. A small channel on the mother’s abdomen collects the milk, which is then lapped up by the young. Strangely, the babies are actually born with teeth, but lose them before adulthood. Such is the impracticality of platypus design…

Adorably impractical.
(Via: noahbrier.com)

Finally, let’s explore platypus hunting methods. Platypuses are the only mammals with the sixth sense of electroreception. Those leathery duck bills of theirs are actually precision receptors that can detect the electric fields created in the water by the contractions of muscles in their prey. Considering the prey in question is largely worms and insect larvae, we’re talking big-time sensitivity here. The bill is also very receptive to changes in pressure, so a movement in still water can be picked up in this way as well. Researchers have suggested that by interpreting the difference in arrival time of the pressure and electrical signals, the hunter may even be able to determine the distance of the prey. This would be especially useful, given that platypuses close both their eyes and ears when hunting. In fact, they won’t even eat underwater; captured food is stored in cheek pouches and brought to land to be consumed.

So there you have it. The platypus: even weirder than you thought.

[Fun Fact:The female platypus has two ovaries, but only the left one works.]

Intelligent Design’s Worst Nightmare
(Via: Animal Planet)

Says Who?

  • Brown (2008) Nature 453: 138-139
  • Grant & Fanning (2007) Platypus. CSIRO Publishing.
  • Graves (2008) Annual Review of Genetics 42: 565-586
  • Moyal (2002) Platypus: The Extraordinary Story of How a Curious Creature Baffled the World. Smithsonian Press.

Vacation Time!

Time for a break, dear readers. For the next two weeks, I’m off to the farm to do as little as possible!

I’ll be thinking about new and exciting freaks and oddities to write about, so if you have a request or suggestion for a future post, be sure to write a comment, and I’ll see what I can do.

I’ll be back September 5th with a new article. Until then, for your viewing pleasure, here are some photos of my favourite place to pass the last days of summer…

(Click on a photo for a larger view.)

Our Nearest Neighbours

Remains of an Old Wagon

Dawn on the Farm

Early Morning Soybeans

The End of the Day

The Dirt Road to the End of the World

Killing Me Softly, or, The Fatal Embrace of the Strangler Fig

(Via: Wikimedia Commons)

Common Name: Strangler Figs

A.K.A.: Ficus species

Vital Stats:

  • There are around 800 sp. of figs, over half of which are hemi-epiphytes, like stranglers
  • Around 10% of all vascular plants are epiphytes (about 25,000 species)
  • The trees which produce the figs we eat are terrestrial, and do not grow in other trees

Found: Tropical forests of Latin America, Southeast Asia, and Australia

It Does What?!

What does it take to squeeze the life out of a full-grown tree? A lot of time and some very long roots, apparently. Many parasites eventually bring about the untimely death of their hosts, but few do it as slowly and as insidiously as the strangler fig.

Stranglers begin life as a tiny seed that leaves the back end of a bird and happens to land on a tree branch high in the rainforest canopy. The seed germinates, and the young fig begins to grow as an aerial plant, or epiphyte, taking its moisture from the air and its nutrients from the leaf litter on its branch. Thousands of plant species, including most orchids, grow in this manner. But then an odd thing begins to happen. The seedling produces a single long root. Very long. From tens of metres up in the canopy, this root grows all the way down to the ground. Many young stranglers will die before their questing root reaches the earth, but for those that make it, a connection is formed with the soil through which water and nutrients can be extracted. From this point on the great, towering giant which holds this tiny little interloper is in mortal danger.

The strangler fig, playing “harmless epiphyte.”
(Screenshot from The Private Life of Plants, BBC)

A secure connection to the soil allows the fig to speed up its growth and to begin sending more and more roots earthward. Rather than dropping straight down, like the initial root, these later organs will twine around the bark of the host tree. At first, the roots are tiny, like mere vines crawling over the host trunk. Over time, however, they thicken, covering more and more of the trunk’s surface. Where they touch or overlap, the roots actually fuse together, forming a mesh over the surface of the bark. Up above, the stem of the strangler is growing as well. It rises through and above the host branches, soaking up the light and leaving the other tree shaded and starved for energy.

In fact, this is a war fought on two fronts. As the starving host tree struggles to gather light energy to send downward from the leaves, it is also increasingly unable to bring water up from its roots. This is because the tree’s trunk continues to expand even as the strangler’s grip grows tighter around it. These opposing forces effectively girdle the tree, crushing the vascular tissues that carry moisture from the soil. Eventually, the battle is lost and the tree dies. Fortunately for the fig, its major investments in root growth have paid off – the dead host tree does not fall, taking the strangler with it. Instead, it simply rots where it stands. Finally, many years after its arrival on the scene, the strangler fig has achieved independence. It is now a free-standing tree, completely hollow and supported by its interwoven lattice of aerial roots.

The first root finds the ground.
(Screenshot from The Private Life of Plants, BBC)

So what happens when more than one strangler fig seed lands on a particular tree? Something quite unique… the roots of the different individuals fuse and form an organism which is indistinguishable from a single tree, except by molecular testing. These are what biologists refer to as ‘genetic mosaics.’ What’s more, the individuals actually begin to act like a single tree. You see, figs typically have staggered flowering times, such that it is unlikely for numerous trees in a small area to be in bloom at the same time. This helps in keeping their wasp symbionts well nourished. Once trees fuse, however, they seem to become physiologically linked as well, with researchers reporting that they bloom as a single individual.

The most hurricane-proof tree ever.
(Screenshot from The Private Life of Plants, BBC)

[Fun Fact: Some strangler fig species have very high growth rates, and huge individuals have actually been found engulfing abandoned buildings in the tropics.]

Says Who?

  • Harrison (2006) Journal of Tropical Ecology 22(4): 477-480
  • Perry & Merschel (1987) Smithsonian 17: 72-79
  • Schmidt & Tracey (2006) Functional Plant Biology 33: 465-475
  • Thomson et al. (1991) Science 254: 1214-1216

Don’t meditate under strangler figs.
(Via: Flickr, by vincenzooli)