Antlions: the truth behind Star Wars

Anyone who has ever seen The Return of the Jedi will be familiar with Luke Skywalker’s and Han Solo’s plight as Jabba the Hutt attempts to feed them to the sarlacc, which lurks in the bottom of the Great Pit of Carkoon. What might surprise you though is this isn’t far from the truth and many insects live in very real danger of coming face-to-face with such a creature, which is known as the antlion. 

As their comparison to the fictitious sarlacc suggests, antlions are ambush predators and are fairly common worldwide. In fact, they are found in almost every dry, arid environment and around 2, 000 species have been described so far that belong to the family Myrmeleontidae. Like many insects, antlions have a complex life cycle and pass through a larval form before they finally mature into adults. Due to this, the term ‘antlion’ is usually reserved to the larval form of the insect (which are sometimes called doodlebugs due to the spiralling trails they leave in sand while looking for a suitable place to build their trap), as an quick way to identify the form of the insect. 

Just like the sarlacc is, antlions are terrors and are capable of eating almost any arthropod that is unlucky enough to fall into one of their traps. Thus, their diet consists of a variety of insects that ranges from ants (obviously) and termites to small spiders! How their prey is caught however, depends on the exact species of antlion and their surrounding habitat, meaning that they could be lurking in foliage, hiding in the cracks in rocks and bark or be waiting in especially dug pits. 

Unusually among insects, antlions lack an anus and store all of their waste inside their bodies until they undergo metamorphosis (where it is discarded with the remnants of their cocoon).

It is the species that dig pitfall traps in sand that are particularly renowned however, and much research has been carried out into their trap-building behaviour. Typically, antlion pitfall traps are about 3 inches wide, 2 inches deep and are dug in finely grained, loosely packed sand. This criteria allows an antlion to create a steep, treacherous pitfall that their prey struggle to escape from once they've fallen into it as the walls crumble beneath their feet. To make their escape even harder, the antlion will then toss sand at the struggling insect to create a mini ‘landslide’ that helps to drag the struggling insect further into the hole. 

And once the insect has reached the bottom of the pit, it's all but game over and the antlion grabs it in its powerful mandibles, injecting deadly toxins and acids into its prey via several long spines that project from its hollow jaws. The antlion, which is firmly anchored in its trap by forward-facing bristles on its legs and body (that prevent it being dislodged and pulled from the pit), then holds its prey still until it has died and sucks the fluid ‘mush’ from the insect - feeding in same grotesque manner as spiders do. And, once the antlion is full, it throws the withered husk of its prey from its trap in the same way as it tosses sand and sets about repairing its walls. 

Antlions can remain in this larval form for up to 3 years, depending of course on the exact species and the amount of prey that is available, before they encase themselves in a cocoon of silk underground. Here, antlions undergo a remarkable process called metamorphosis where they change into their large, adult form over the period of about a month. Once their transformation has finished, the insects emerge from the ground, wait for their bodies to dry out and harden, and take to the air in search of mates.

Depending on the species, antlion damselflies can vary from being fairly small with 2cm wingspans to being much larger with wingspans of 15cm! Adults are much bigger than the larval form and show the greatest difference in size in any holometabolous insect (one that completely changes form via metamorphosis).

Adult antlions are sometimes are sometimes called antlion damselflies (despite having no relation to the damselfly family), and, depending on the species, vary between remaining as fierce predators or switch their diet to eat pollen and nectar. As their nickname suggests, the adult form look similar to damselflies although they can easily be identified by their extremely long, clubbed antennae and very narrow wings. 

Oddly, antlion damselflies are rarely seen in nature because they are usually active in the late evening and are poor flyers so (rather ironically), are very vulnerable to predators. They can be a real nuisance in desert areas however, where they are more abundant, as they tend to swarm and can deliver a mildly painful bite to any humans that they land on!

So, you might agree then that antlions are interesting insects in their own rights - being such fierce and efficient predators - but, considering they are the inspiration behind one of Star Wars' most famous aliens, they become even cooler and are definitely well worth knowing about!

Round & round the straight line

If you’ve ever switched a light on in the dark you’ll have no doubt noticed the rather strange effect it has on moths, which are soon attracted to the light and begin to spiral round it for hours. Many people wonder what causes this bizarre behaviour and, at the moment, there is no definitive answer as even entomologists (the scientists who study insects) find it confusing. 

This isn’t to say that they don’t have theories regarding this behaviour however, and there is one main explanation that is generally accepted among the entomological community that seems to have some scientific evidence. This theory is surprisingly simple and basically works off the principle that lepidopterists (the family of butterflies and moths) use light to navigate when they are flying. 

Like many insects, moths have very poor vision that is mainly used just to detect light and movement.  Most of the information about their surroundings actually comes from their highly developed antennae, which provide them with an incredibly sensitive sense of smell. In fact, the antenna of male moths (pictured above) are so sensitive in some species that they can detect a single molecule of a female moth's sex pheromone in 1 cubic yard of air - allowing them to smell the moth from 11 kilometres away!

So, to start at the basics, there are two fundamental responses that all types of life (that are capable of detecting photons) have in response to light – they either respond positively to it and move towards the source (positive phototaxis) or negatively and flee from it (negative phototaxis). Lepidopterists are known to be the former, which explains why they converge on sources of light (such as bulbs). 

And while this appears to make sense so far, it is actually confusing to many scientists – why would an insect that is vulnerable to predators move towards a light source and make itself more visible? In fact, logic suggests that moths should actually show negative phototaxis and head towards the darkest areas they can find – they do have drab colours for camouflage afterall! 

However, the idea that lepidopterists use light for navigation helps to explain this and gives a plausible reason why they are in fact attracted by ambiance rather than repelled by it. The idea is simple and suggests that lepidopterists use the brightness of the lights in the sky (i.e. the sun, stars and moon) to calculate how high they are flying and use the angles that these lights hit their eyes to determine their direction. Thus, they think that because the lights are getting brighter, they are actually getting higher in the sky (which generally makes them safer from many of their predators, such as spiders, which live amidst foliage). 

So although this might seem like a bizarre explanation for why moths are attracted to light, remember that moths have evolved over millions of years in an environment where the brightness of the night sky has scarcely changed. It is only recently that humans have invented and built all of these streetlights and exterior lamps that are confusing them! Essentially, all the light we produce at night is hijacking their complex and highly evolved navigating systems because they now get much close to sources of light than they are expecting to! 

This concept also explains why moths end up spiralling round bulbs for hours at a time and, basically, because the stars and the moon are so far away from us, their light hits moth eyes in parallel to the horizontal axis of flight. Thus, moths have evolved a system where they use the information that this light provides to work out whether they are turning or travelling in a straight line. (Think of a cross where the flat line represents direction and the vertical one represents height).

This system is actually fairly simple and works well, until of course they become too close to a light. Once this happens, the angle the light strikes the eye at is steep enough to make the insect think that it is turning so it constantly has to compensate and turn itself to ‘return’ back to a straight line of flight. Thus, while we can see that the moth is actually flying in circles around the light, the disorientated moth thinks that it is flying in a straight line! 

And if this isn’t enough for the poor moths to contend with, many lepidopterists also believe that because moths are nocturnal (sleep during the day), being close to such a bright light actually makes them sleepy. When this happens, they are believed to enter a ‘rest mode’ and attempt to sleep, which is why they often try to land on (or nearby) the light – making it even harder for them to escape its clutches!

Scientists discover a new type of cell division!

Until now biologists have thought that human cells can only replicate using a type of cell division called cytokinesis, where a somatic (body) cell splits into two new daughter cells after doubling the quantity of DNA that it contains via a process called mitosis. Dr. Mark Burkard from the University of Wisconsin Carbone Cancer Centre however, has discovered that this is not in fact the only way! 

Since klerokinesis is a completely unseen form of cell division, Dr. Burkard and his team conducted a number of experiments to confirm that it was definitely a new type of division. Once they were satisfied that it was, they asked William Brockliss (the University of Wisconsin's professor of Classics) to help them develop the name and decided on the prefix klero-, which means 'allotted inheritance'. 

The new type of cell division, called klerokinesis, appears to occur in somatic cells that already have more DNA in them than they should and results in the production of two daughter cells that actually have the correct number of chromosomes in them! 

Although cells containing more DNA in them than they should may not sound like a big deal, it is and many cancers and diseases such as Down’s Syndrome are actually the result of this extra genetic material. For example, about 35% of all pancreatic cancer cells and 14% of breast cancer cells have three sets of chromosomes in them rather than two! 

Dr. Burkard and his colleagues believe that klerokinesis may actually be one of the body’s emergency ‘back-up’ defences to eliminate cells with too much genetic material in them so that they don’t build up in the body. This hypothesis appears to be supported by the results of his research, which found that 90% of the cells that he had purposely tried to produce with three chromosomes instead of two in them (as part of his breast cancer research), divided early in the mitotic cell cycle after an unusually long rest period to produce ‘normal' cells! 

Dr. Burkard and his colleagues are excited about discovering that abnormal cell division rarely has any long-term detrimental side-effects and believe that this research could have huge implications in our war against cancer. In fact Dr. Burkard has said that he would like be able to actually push 99% of cells towards klerokinesis by the end of his research as “if we could push the cell towards this new type of division, we might be able to keep cells normal and lower the incidence of cancer”.

Beneath the trapdoor danger lurks...

Wherever you go, you are bound to find spiders. They are an ancient class of predator and have learnt to use poisons, brute force and complex webs of silk to terrorise and instil fear into animals on every continent of the world except Antarctica. 

Typically, an easy way to tell the rough age of a species of spider is by looking at the complexity of the web it spins and the general rule is that the more elaborate the web, the younger the species of spider. This makes sense really as it would be expected for more complex structures, such as web scaffolding patterns, to take longer to evolve! Thus, the infamous tarantulas, which use silk only to line their burrows for warmth, are among of the oldest species of spider on the planet. 

Trapdoor spiders are another ancient lineage of arachnid, which is suggested by the simple manner in which they use silk. They use silk for the same purpose as many more ‘modern’ spiders since they rely on it to convey vibrations to them to show that prey is nearby, but do not spin it into complex webs. 

There are more than 500 different species of trapdoor spider that have been described so far, which can be found in tropical regions all across Earth. Despite being large and looking fairly intimidating, trapdoor spiders are rarely aggressive and are not dangerous to humans.

So instead of building silk nets like many newer species, trapdoor spiders dig a deep burrow in the soil (some species make a long tube of silk instead) and spin trip-lines that radiate out from the tunnel’s entrance. The spider then lurks near the mouth of its burrow, touching its trip-lines, and waits for an insect to knock one of the threads. When this happens, the spider feels the vibration and lunges out to grab, bite and poison its prey. 

Many species of trapdoor spider take this ambush tactic a step further and actually build a covering over the hole of their tunnel. This ‘trapdoor’ is what gives the family of spiders its name and is cleverly made from materials surrounding the burrow, such as soil, vegetation and silk, so it is camouflaged perfectly with the ground! 

Species that make a trapdoor always hinge their covering at one end with thick webbing and hold it down tightly using special claws on the ends of their feet. When its trip-lines are activated, the spider flips open its trapdoor, explodes out of its burrow and drags the hapless insect back inside for its dinner! And because trapdoors are typically very large spiders, almost all insects are on their menu – with meals commonly including cockroaches, crickets, grasshoppers, beetles, moths and other spiders. 

As would be expected, trapdoor spiders invest such a huge amount of time and energy in digging their burrows that they are a very shy and reclusive species. In fact, trapdoors rarely leave their burrows at all and female spiders typically spend their full 20 year lifespan in one burrow! It is usually only males that venture out from their burrows and even then, only once they have matured sexually and are seeking a mate. Like all spiders, male trapdoors mature near to the end of their lives (which are much shorter than those of females) so are inclined to take huge risks in finding a mate before they die. 

Once a male spider has mated with a viable female, the male dies (often to be eaten by the female) and the female remains in her burrow to feed her spiderlings when they hatch. Shortly after hatching, the spiderlings venture out of their mother’s burrow to dig their own home using their front legs and specialised barbs on their fangs called rastellum that help them to move soil.

Hangovers: what are they & can we avoid them?

With Christmas and New Years over, many of us will be looking back over the festive periods to remember the glittering decorations that adorned our homes, opening our presents, spending time with our loved ones and indulging in rich, expensive foods. And of course, no memories of the Christmas holidays are complete without those of the hangover and it's safe to say that many of us will have just as vivid memories of times spent inebriated and of those nursing the unpleasant headaches and tender stomachs that inevitably followed a night's heavy drinking. The hangover is unarguably the bane of many of our celebrations and often leads to promises of “never again”. 

Of course, there always is an again and we all know full well that we’re not fooling anyone when we make that particular promise. The call to drink when we're enjoying ourselves is just too strong! So, we will all drink again and will all suffer for it again. Yet despite knowing to expect a hangover the next morning, do we really know what one is? 

The British National Health Service (NHS) recommends that men should not regularly consume more than 3-4 units of alcohol per day and women should not regularly consume more than 2-3 units. By 'regularly', the NHS means drinking these amounts on most (more than four) days of the week.

The answer to this question is in the properties of ethanol, the alcohol present in drinks, itself. Basically, ethanol is a powerful diuretic drug (like those discussed in the earlier post: 'Coca Cola: Christmas in the toilet'), and dehydrates us by making our body absorb less water. As our body becomes dehydrated and less begin to lose water, the cells that form it shrink and contract – leading to severe problems for the brain! 

This is because the human brain is surrounded by three thin membranes that are collectively known as the meninges. Thus, as we become dehydrated and the cells in these membranes shrink, the meninges contracts and squeezes our brain. It is this squeezing effect that is responsible (predominantly) for the headache we suffer the next morning and, obviously, the more we drink, the more dehydrated we become so the brain is squeezed more and we have a worse headache for it! 

Furthermore, this squeezing effect is also slightly responsible for any memories we may have lost, working in conjunction with the disruptive effects that ethanol has on the normal activities of the brain’s neurotransmitters (which leads to the associated behavioural changes and loss of coordination and response speed that are also experienced when drinking alcohol). And, as the brain is squeezed, it compresses the areas of our brain that deal with the formation and storage of memory - impairing its blood flow. This means that these areas work less much efficiently than they do normally and we end up with ‘holes’ in the night’s events when we look back on it. 

Whereas dehydration is responsible for our headaches, it is not the cause of the feeling of nausea that is also associated with hangovers. This feeling is due to another of ethanol’s particular properties, in that it is one of the few chemicals to be absorbed straight into our bodies through our stomach lining (paracetamol is another, which is why the drug alleviates pain so quickly). As well as meaning that alcohol affects us very quickly, particularly on an empty stomach, large amounts of ethanol passing through the stomach lining can leave it feeling sore and inflamed – which is also what causes the stomach ulcers that are a common symptom of long-term alcohol abuse! 

Fairly obviously then, if our stomachs are sore then they are not going to be very welcoming of food – particularly those that are heard to digest. Furthermore, vomiting the night before (which is actually beneficial for the body as it’s a protect reflex it uses to expel ethanol once it knows that much more is being absorbed than can be broken down safely), would make the feeling worse as it could itself damage the stomach lining and leave the stomach muscles strained and fatigued. 

As well as due to ethanol, the feeling of illness and lethargy experienced in hangovers are also caused by impurities in the drinks themselves, which are a result from the brewing or fermenting process. These impurities affect the body in many different ways and often require investments of large amounts of energy to break them down (which is why you should avoid mixing drinks). Due to the nature by which these impurities are created, different drinks contain different culprit chemicals. So your body might be coping, say, with those present in your red wine, but when you switch to whiskey later, it will have to start synthesising different enzymes to break the new chemicals in the whiskey down. As there are only so many enzymes that can be made at any one time (and a finite allocation of resources to use), the body ends up not producing enough enzymes to cope with either of the chemicals – meaning of course, that your hangover will be much worse! 

And so, now that you have a fair understanding of what hangovers are you might want to know whether or not they're possible to avoid. Sadly, they're not – not unless you cease drinking anyway, which let’s face it, isn't going to happen and seems a little excessive... But hangovers are possible to minimise, with surprisingly little effort. 

1. Don’t drink on an empty stomach. Eating a large meal of foods that are high in carbohydrates, such as pasta- or rice-based dishes, before you begin drinking will absorb some of the alcohol and so slow the rate it passes into your bloodstream. Likewise, drinking full-cream milk or eating high fat foods beforehand are beneficial since fat actually inhibits alcohol absorption, so less will be absorbed into your system. 
2. Avoid ‘dark’ drinks. As a general rule, darker beverages such as red wine, brandy and whiskey, contain more of the contaminants discussed above so will harder for your body to process. Instead, try drinking clear drinks like white wine, vodka and gin. 
3. If you're out and about, avoid buying ‘rounds’. Everyone drinks at different rates and have their own limits and so, by drinking rounds, you are having to match your own consumption to those around you (and let’s face it, the quickest drinkers always pressurise others to hurry up so “we can get the next round in”), which may be more than you can handle or want to drink that night. 
4. Stop drinking early. Usually, we drink to get drunk. So when we are finally drunk, we've normally got a lot of surplus alcohol in our stomachs’ that has yet to be absorbed. If you take this into consideration and stop drinking once you've reached your limit (or at least slow down), your body will have longer before the morning to have cleared the alcohol from your system and your hangover will be less severe as the result. 
5. Drink as much water as you can before bed and take a bottle of water with you. This way, you’re drinking water that will not only dilute the alcohol left in your stomach and system, but will rehydrate some of the water that you've lost over the course of the night - alleviating the crushing pressure on your brain. 
6. Try and force a ‘full-English breakfast’ down in the morning, or something similar (like McDonald's). As discussed earlier, fatty foods inhibit alcohol absorption so by eating foods such as sausage, bacon and eggs, you can stop the last ‘dregs’ of alcohol in your digestive tract from being absorbed. 
7. Avoid drinking caffeine. Caffeine is another diuretic, so although they may make you feel better in the short term, drinks like tea and coffee will only make you more dehydrated. This will not only make your headache worse, but will prolong it as well. Instead, drink fruit juices (not from concentrates if possible), as the sugars and vitamins they contain will ‘refresh’ your body and help to restore its vitality.

If you're concerned about the effects and dangers of alcohol or want more information, click here to be taken to the NHS' alcohol help and guidance pages.