Archive for October, 2013

All that glistens is not gold

Posted: October 26, 2013 in Amphibian

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Its been just about a year since I started this blog; under circumstances still somewhat mysterious to me. According to the memories, or to use a more exact phrase, testimony, of my flatmates at the time, this occurred around the time I met someone called ‘Jack Daniels’; whom one day I hope to track down and see if he can shed any light on matters.

But anyway, incredibly, it appears some people, a few of them not motivated by a mixture of fascinated horror, contempt and pity, actually do read this blog. Using the viewing figures, aided by my favourite hobby (unwarranted extrapolation of statistics) I’ve managed to work out that by this time next year my viewing figure will be approximately eleven billion people. I mention this only because a) it indicates that we’ll find another four billion or so people during the next year and b) it’ll give you lot some time to get used to this blog changing from ‘an occasionally updated blog about animals’ to ‘the centre of a terrifying cult holding all humanity in its iron grip’

We’ve already designed our new offices!

This obviously brings us on to what animals should represent this blog, and after an intensive thought process lasting literally minutes, I’ve come to the conclusion that it should be the Golden Arrow Frog, or Phyllobates terribilis for a number of reasons.

Firstly, it is a nice, golden colour. Gold is of course associated with wealth and power, and since this blog has precisely zero of either, its presence will allow us to project an image which is far beyond our actual means. In addition, having a bunch of golden frogs hopping around might fool people into thinking that our success is based on solid financial foundations, rather than a combination of bluff and jaw dropping stupidity on the part of banking regulators.

Five dozen golden frogs hopping around the lobby is worth any amount of ‘Annual Reports’ and ‘Regulatory Frameworks’.
(Image credit: Wikimedia Commons)

Secondly, it is from Colombia, which should please some perfectly legitimate businessmen in that country that we have occasional and utterly legitimate dealings with that are of no interest to anyone.

Thirdly, its cute! Its only about five centimetres long (females tend to be slightly longer) and lives in groups. A bunch of small, golden frogs, all hopping around and playing together will bring a smile to the face of even the most cynical and suspicious detective, regulator or politician, and persuade them to drop whatever ‘investigation’ or ‘inquiry’, or ‘inquest’ they are contemplating. In addition, they also eat insects (especially ants) and other invertebrates, which should cut down on pest control costs and the amount of cleaning staff. Which is good, because the idea of having loads of people wandering around our building unsupervised and potentially getting the wrong impression from certain documents gives us the heebie-jeebies.

Would this cheeky chappie be involved in anything suspect? (Image credit: Wikimedia Commons)

 

Fourthly, its brave! This blog is brave, in that we are utterly unafraid to reveal the flaws of our opponents if there is no risk to us. In the same way, these frogs were observed to hop around cheerfully, and to never attempt to hide away from potential predators.

Therefore, I think it is obvious that these frogs are more than perfect to be the mascot of Horrific Animals of the World. Now, there are several drawbacks, I admit. The first, and indeed only one is the fact that it is slightly toxic, and by ‘slightly toxic’ I mean ‘extremely, incredibly, amazingly toxic, seriously-you-would-not-believe-how-toxic-this-very-small-frog-actually-is’; in fact there is some argument for suggesting that this frog might be the most toxic animal in the entire world. This is because their skin contains the alkaloid toxins batrachtoxins. Each frog has around 1-2mg of this toxin in its skin, which we admit it 1-2mg far, far too much. These toxins bind to sodium channels in cell membranes; which results in the nervous system becoming paralysed (since sending action potentials requires the cells to become polarised and then depolarised) (Dumbacher et al 2004). This results in heart failure, gagging, drooling and convulsions and probably death.

To kill one mouse requires around 0.05 micrograms of this toxin. To put this in perspective, one microgram is equivalent to one millionth of a gram, which is obviously such a small amount you can’t actually imagine it. Assuming each frog contains just a miligram of toxin, this is enough to kill 20,000 mice. So, on the plus side they could be quite useful in controlling the plague of mice our offices will undoubtedly suffer from, but on the minus side it does equate to each frog carrying enough toxin to kill many, many people. The toxin is also rather persistent; the researchers who originally described the frog report accidentally killing a dog by letting it sniff around on garbage on which gloves and bags used to handle the frog had been discarded.

(Boring bit here. Ed.) (Actual comparisons are hard; as a) it is unrealistic to just scale up toxicity (in terms of lethal dose per gram of tissue) from mice to man, and secondly the toxic dose varies enormously depending on whether the toxin is ingested, absorbed through the skin or injected; my own very rough calculations figure that one frog would kill (at the extreme high end) around fifty people if the toxin was injected, or around five if it was injected. These warnings apply to pretty much every attempt to work out the lethal dose of a toxin, whatever it is. The fact remains, however, that these frogs are extravagantly toxic, even compared to other poison dart frogs.

Now, the interesting thing about these frogs, aside from the fact that some depraved individuals feel that they might be a suitable mascot for their blogs, is that the frogs might not actually produce the toxins themselves. The researchers who first described the frog saw that the frog’s toxicity slowly decreased over time. This was originally put down to stress, but slowly it became apparent that this was not the case as frogs born in captivity did not contain these toxins. Instead, it is thought that the frogs somehow gain the toxins from their environment. Curiously, some birds from nearby New Guinea (from the genus Pitohui, as well as the species Ifrita Kowaldi), also have these exact same toxins in their own skin and feathers. In 2004, these same toxins were found in Choresine beetles, which is presumably where both the frogs and the birds get their toxins from; meaning that in some ways these beetles have the most useless counter-predator device ever evolved.

 

Besides, who ever heard of having a beetle as a mascot? We’ll stick with our cute, lovable, happy-go-lucky, plucky and extravagantly lethal frogs, thank you.

 

(You’ll notice there weren’t any references in this; but three sources I found very useful were a) the original paper describing Phyllobates terribilis (Myers, Daly and Malkin 1978), the paper describing the toxin also being found in birds (Dumbacher, Spande and Daly 2000), and the paper describing the source of the toxin, which also has some useful background (Dumbacher et al 2004).

The first paper in paticular is very useful, containing both everything you could ever hope to know about this frog, and the immortal line “such observations persuaded us against tasting secretions from…P. terribilis, since there seems a distinct possibility that respiratory difficulties might be encountered.”).

It just bugs me….(sorry)

Posted: October 8, 2013 in Arthropods

Have you ever thought about all the lies that you were taught as a kid?

Now, I’m not talking about you if, say, you went to school under the Taliban. There, you were undoubtedly taught that America is the embodiment of all evil; that stoning homosexuals to death or burying them alive is the most fun you can have in a sports stadium, and that if a girl wants to go to school, a wholly reasonable approach is to shoot her in the head. All of these, you may notice, are kind of completely untrue.

No, what I mean is the well meaning lies we were all taught about in primary school. Like, for example, ‘everyone’s opinion should be respected’. Why teachers even mention this is completely beyond me. Firstly, kids are stupid, and their opinions are thus completely worthless. Secondly, a quick glance at a comment thread almost anywhere on the internet, or a conversation with someone who believes in homeopathy or creationism or whatever, kind of shows that actually a great many people have opinions which should not be respected at all. Or ‘everyone’s good at something’, which again is utterly untrue. Quite a lot of people are good at literally nothing; although I guess this is a harsh lesson to teach to a group of seven year olds. Harsh, but I would argue necessary.

But of course, the real corker is ‘never judge a book by its cover’ or ‘don’t rely on first impressions’ or whatever. Again, I can see why kids are taught this, but it is a pretty rubbish lesson. On the whole, first impressions are backed up by second, third and eighty seventh impressions. For example, if you have a swastika tattooed on your face, I may instantly draw the conclusion, rightly or wrongly, that you are a bit of a fool. I might even go so far as to speculate you are not a nice person.

Again, I could be wrong, but I suspect this man is not great at making long term life choices.

And this does not at all bring me smoothly on to the assassin bug; or, more precisely, to the assassin bug known as Acanthaspis petax. Now, it carries around a bunch of dead ants on its back, which I think we can all agree is slightly weird. Even a teacher who has never, ever, ever judged on first impressions might agree that a bug that is called ‘assassin’ and which carries around dead corpses attached to its own body is, perhaps, an animal deserving of being named as a (drum roll please, underpaid interns) Horrific Animal of the World.

“And this weeks contestant – an insect from South East Asia which gives a new meaning to the words ‘fashion victim’… (Image credit orionmystery.blogspot)

And they’d be right.

Like all assassin bugs, it is a member of the Reduviidae family of insects, which is the largest family of Hemiptera, or ‘bugs’. Now, ‘bugs’ are defined as proboscis (formed from insect mouthparts joined together) possessing insects; basically they have a straw which they use to suck out juices. Aphids, for example, are bugs which use their proboscis to suck out plant juices. And, since we are not judging books by their covers, or in this case bugs by their names…

…we’re forced to conclude that actually, assassin bugs fully deserve their name. What they do, you see, is locate a prey insect (which varies from species to species) and seize it with their legs. The stylet (like a sharp straw) is punched into the prey. This rasps away at the prey’s insides, reducing the prey’s innards to mush. However, because nature is cold and pitiless, the horror does not end there. The bug then injects toxins and digestive enzymes, such as amylases and proteases into the prey; breaking down the prey’s body inside its own exoskeleton into a soup which the assassin bug then, simply, slurps up through its proboscis (Cohen et al 1990, Sahayaraj and Muthukumar 2011).

But lots of bugs do this! What makes Acathaspis petax so special?

Well, what it does is, rather than discard the sad, broken husk of its prey, add insult to agonising death and use sticky threads to bind the corpse (usually an ants) to its own body. For a long time, no one was quite sure why it did it; aside from a few theorists who speculated that the bug wanted to fully embrace the notion of becoming a serial killer; although once again nature has gone one better than humanity – off the top of my head, I can’t think of one psychotic murderer, real or imagined, who went around with as many as twenty of his victim’s corpses on his back.

“Carrying around all those murdered college students gives me backache”

However, in 2006 the mystery was partially solved (Jackson and Pollard 2007), after a group of scientists, presumably after taking several swigs of morale boosting brandy, found that the mountain of ant corpses on the bug’s back acted as defence against a group of spiders called salticids, which hunt almost exclusively using vision. The spiders stalked ‘naked’ bugs – i.e. bugs without a decent covering of ants – far more than they did ‘clothed’ bugs. It was theorised that the pile of dead ants on top of the bug’s back hid the shape of the bug and confused the spider. In addition, it had previously been noted (Cooper and Vitt 1991) that when a spider did jump on a bug, there was a chance the pile of corpses would fall off the bug, allowing the bug in all the confusion to escape. Finally, it may use ants in paticular for this purpose because ants tend to swarm and attack other predators – so the spider might be wary of attacking a big ball of (admittedly somewhat inert) ants (http://notexactlyrocketscience.wordpress.com/2008/01/01/assassin-bugs-deceive-spiders-with-coat-of-many-corpses/ ).

So this bug wears a suit of murdered ants to protect it from ravenous spiders which could leap at it at any moment. Gotta love Nature. (Picture credit eversostrange.com)

 

 

Oh, and just in case you haven’t lose enough sleep yet – there are some assassin bugs that feed on vertebrate blood. Sometimes, they are called “kissing bugs”, because they tend to bite on the lips or other parts of the face; making it, after a sloppy kiss from a drunken coworker who has just vomited all over the boss, the very worst kiss you can possibly have. And, to put the cherry on it, they can carry the parasite which causes Chagas disease. This can cause, in the short term, fever, fatigue, aches, diarrhoea and vomiting. In the longer term it can get worse, leading to heart problems, damage to the nervous system and recurring bouts of illness – its thought that Charles Darwin was bitten when he travelled around the world on the beagle, which explains the frequent attacks of sickness he suffered throughout his life.

All from one little bug.