On Tuesday Bug Explorers became the home for a whole pile of bugs, including Emperor scorpions, hissing cockroaches, giant african millipedes and more. Check the bug house list for more details Since then, I've been desperately trying to organise them into new enclosures and making sure they're all healthy, happy and well looked after.
They have all been kindly donated by Explore@Bristol as the critters were not getting the use that they deserved among their busy school workshop schedule. The Bug Explorers have promised to get them working a bit more often and will be making sure they're in schools as much as possible. Once everything is ready they will all be given some space on the blog, but for now I must go and clean out a giant African land snail!
Thursday, 29 July 2010
Saturday, 24 July 2010
Mantises - perfect predators
Next week, Bug Explorers will expand massively with an influx of new critters that will pretty much complete the collection for the time being. For now, the newest addition to the bug house is a beautiful, fierce and gruesome predator that looks like it has come from another world, a Peacock Mantis, Pseudempusa pinnapavonis.
It may just be because I've just been to see the new Predators film (No Arnie, no point in my opinion) but their heads to bear a striking resemblance to the dreadlocked death-machines from the film. Couple that with a slender, spiky body that could be out of Aliens and they're a sci-fi nerd's dream bug.
It's not just in appearance that these guys seem like aliens, their behaviour is pretty strange too. Unlike other predatory bugs such as many arachnids, ants or centipedes, mantisesrely on sight as their primary sense used for hunting.They are great at seeing movement, like many insects, but also and have a "sweet-spot" or fovea that can resolve detail at a distance of potentially up to 50 feet. Although this is not that remarkable in human terms, for an invertebrate, particularly one with compound eyes it is unusually good.
They have good depth perception too, and will sometimes sway like sick insects do to improve this by using parallax, before hitting out with their strong and spiky forearms. Their use of crypsis is like stick insects too, their colouration and shape enables them to blend perfectly into their background and stalk their prey. The cricket doesn't stand a chance, and is eaten while still nominally alive. Twitching at least. You can actually see that the antenna are moving in this picture, and while insects do not have a nervous system like us or pain receptors like mammals and other vertebrates do, you've still got to feel a bit sorry for the thing.
That is not to say that other predators like spiders are in some way morally better for killing their prey a bit quicker. Predators kill their prey in a quick and efficient way to protect themselves, not spare the prey's suffering. Imposing human ideas like suffering, morality and pity is anthropomorphism (something I wrote an entire dissertation on) and although these are natural human responses to this issue, they are not scientifically appropriate. How and why prey are killed are interesting scientific questions, but anthropomorphism obscures the science if not used carefully. For a mantis, there is no need to ensure a prey item is dead because there is no escape from it's vice-like grip. For a spider, venom is required to eat because of its mouthparts.
Female mantises are notorious for eating males during or after copulation, which when seen from a human perspective seems horrific. Considered through the eyes of natural selection, however, this must be a successful strategy for mantises. Male mantises provide only genetic material for the next generation, making no further contribution to their offspring. Females that eat their partners get more food than those that do not, so are better nourished to provide a ootheca (egg sac) for the several hundred baby mantises to grow inside. If fact, it could be said that being eaten is the male's contribution to this next generation. Of course, males that can escape their hungry partner can then go and find another females to mate with and so may produce many thousands for fertile eggs, but these females may be under-nourished and so the eggs never survive to reproduce themselves. This is the essence of natural selection; anything genetically based (which can include behaviour) that improves the chances of the next generation's survival will flourish. Female mantises tend to be larger and stronger than the males and so can, if hungry, eat them. Male mantises are also able to continue copulation whilst being eaten (as I said before, their nervous systems are very different from ours). Both behaviours help the survival of the next generation, regardless of how we may regard to view them as humans. Of course, this behaviour would not work in animals that require more parental care from both parents, as is the case in most vertebrates, but it does go to show that nature is not nice, or nasty.
Still, natural selection rants aside, despite being highly successful predators, mantises are prey for many larger species such as mammals and birds. The latin species name of the Peacock mantis, pinnapavonis, literally means "peacock tail", because of peacock-like eye spots on the adults wings that are used as a threat display. T
his little juvenile is too young for that at the moment, but if faced with danger (in this case being threatened with a biro) they will hop around then collapse on the floor and play dead. Rather than apparent death, or thanatosis, which is found in animals like opossums and some snakes, this is more likely a use of their crypsis as the brown colouration of the body makes them hard to spot. Thanatosis relies more on predators preference for live prey to put them off, although some scientists do consider it a form of crypsis.
It seems that the playing dead behaviour may be more common in males, so I think the mantis may be a he. He is as yet unnamed though, so name suggestions in the comment box please!
It may just be because I've just been to see the new Predators film (No Arnie, no point in my opinion) but their heads to bear a striking resemblance to the dreadlocked death-machines from the film. Couple that with a slender, spiky body that could be out of Aliens and they're a sci-fi nerd's dream bug.
It's not just in appearance that these guys seem like aliens, their behaviour is pretty strange too. Unlike other predatory bugs such as many arachnids, ants or centipedes, mantisesrely on sight as their primary sense used for hunting.They are great at seeing movement, like many insects, but also and have a "sweet-spot" or fovea that can resolve detail at a distance of potentially up to 50 feet. Although this is not that remarkable in human terms, for an invertebrate, particularly one with compound eyes it is unusually good.
They have good depth perception too, and will sometimes sway like sick insects do to improve this by using parallax, before hitting out with their strong and spiky forearms. Their use of crypsis is like stick insects too, their colouration and shape enables them to blend perfectly into their background and stalk their prey. The cricket doesn't stand a chance, and is eaten while still nominally alive. Twitching at least. You can actually see that the antenna are moving in this picture, and while insects do not have a nervous system like us or pain receptors like mammals and other vertebrates do, you've still got to feel a bit sorry for the thing. That is not to say that other predators like spiders are in some way morally better for killing their prey a bit quicker. Predators kill their prey in a quick and efficient way to protect themselves, not spare the prey's suffering. Imposing human ideas like suffering, morality and pity is anthropomorphism (something I wrote an entire dissertation on) and although these are natural human responses to this issue, they are not scientifically appropriate. How and why prey are killed are interesting scientific questions, but anthropomorphism obscures the science if not used carefully. For a mantis, there is no need to ensure a prey item is dead because there is no escape from it's vice-like grip. For a spider, venom is required to eat because of its mouthparts.
Female mantises are notorious for eating males during or after copulation, which when seen from a human perspective seems horrific. Considered through the eyes of natural selection, however, this must be a successful strategy for mantises. Male mantises provide only genetic material for the next generation, making no further contribution to their offspring. Females that eat their partners get more food than those that do not, so are better nourished to provide a ootheca (egg sac) for the several hundred baby mantises to grow inside. If fact, it could be said that being eaten is the male's contribution to this next generation. Of course, males that can escape their hungry partner can then go and find another females to mate with and so may produce many thousands for fertile eggs, but these females may be under-nourished and so the eggs never survive to reproduce themselves. This is the essence of natural selection; anything genetically based (which can include behaviour) that improves the chances of the next generation's survival will flourish. Female mantises tend to be larger and stronger than the males and so can, if hungry, eat them. Male mantises are also able to continue copulation whilst being eaten (as I said before, their nervous systems are very different from ours). Both behaviours help the survival of the next generation, regardless of how we may regard to view them as humans. Of course, this behaviour would not work in animals that require more parental care from both parents, as is the case in most vertebrates, but it does go to show that nature is not nice, or nasty.
Still, natural selection rants aside, despite being highly successful predators, mantises are prey for many larger species such as mammals and birds. The latin species name of the Peacock mantis, pinnapavonis, literally means "peacock tail", because of peacock-like eye spots on the adults wings that are used as a threat display. T
his little juvenile is too young for that at the moment, but if faced with danger (in this case being threatened with a biro) they will hop around then collapse on the floor and play dead. Rather than apparent death, or thanatosis, which is found in animals like opossums and some snakes, this is more likely a use of their crypsis as the brown colouration of the body makes them hard to spot. Thanatosis relies more on predators preference for live prey to put them off, although some scientists do consider it a form of crypsis. It seems that the playing dead behaviour may be more common in males, so I think the mantis may be a he. He is as yet unnamed though, so name suggestions in the comment box please!
Sunday, 18 July 2010
The mystery of the unknown caterpillar
A fellow bug explorer found a caterpillar crawling its way around on the floor the other day. Thinking it might be lost, confused or possibly looking for a human to take care of it, the decision was made to find out what it was and see if we could raise it in captivity. A little bit of digging suggested that it may well be the caterpillar of the Lime Hawk Moth, Mimas tiliae. 
Mimas tiliae turns out to be a reasonably common species, particularly in the South of England, that is often found on tree-lined avenues. The adult is a pretty cool looking moth that has nice pink markings on its wings, and it seems to be possible to raise them to adults relatively easily. Only slight problem with that is when it comes to lepidopterans (butterflies & moths) both my fellow bug explorer and I know the theory, but are severely lacking in practical experience. Still, never ones to let that stop us, we're going to do our best. It seems that it's colouration may mean that it was looking for some soil to dig into and pupate over winter. It might take a while, but we'll see if we can raise the little caterpillar into an adult Lime Hawk Moth.
Wednesday, 14 July 2010
Dot, or Todd...?
Dot's eating again after her moult, which is good news all round, except I suppose for the cricket, which is now old news.
Asking around on an insect forum called bug nation about when to expect her to start eating again (www.bugnation.co.uk) a nice fellow called David got me wondering about how I knew Dot was a lady spider... Um... Well... The man in the shop said she probably was...?
A little bit more info about Dot is that she was actually a RSPCA rescue spider who apparently came from a man who accidentally let her escape one day and his wife essentially told him, "It's me or the spider." The spider lost. As a rescue she was free to a good home and Josh, the other bug explorer, and I have been sharing her ever since.
But this got me thinking: what do I actually know about Dot? Well, I am sure she's a Chilean Rose Tarantula, Grammostola rosea, from her size (about 2 1/2 inches wide by 3 inches long) I know she is still a juvenile, I also know she's sometimes a little less docile than many people consider her species to be, and that's about it. David from the forum put me on to an interesting and useful article called How to determine the sex of your tarantula. Be warned though, it is incredibly geeky and does feature the line "until my face is bluer than a Haplopelma lividum' s legs!" No, me neither.
Still, from the article and the very helpful people on Bug Nation, it seems that the jury is currently out on the definite gender of Dot. The evidence points towards her being a her, but there is no definitive answer yet. I may still have to turn her name round the other way and start calling her Todd.
Asking around on an insect forum called bug nation about when to expect her to start eating again (www.bugnation.co.uk) a nice fellow called David got me wondering about how I knew Dot was a lady spider... Um... Well... The man in the shop said she probably was...?
A little bit more info about Dot is that she was actually a RSPCA rescue spider who apparently came from a man who accidentally let her escape one day and his wife essentially told him, "It's me or the spider." The spider lost. As a rescue she was free to a good home and Josh, the other bug explorer, and I have been sharing her ever since.
But this got me thinking: what do I actually know about Dot? Well, I am sure she's a Chilean Rose Tarantula, Grammostola rosea, from her size (about 2 1/2 inches wide by 3 inches long) I know she is still a juvenile, I also know she's sometimes a little less docile than many people consider her species to be, and that's about it. David from the forum put me on to an interesting and useful article called How to determine the sex of your tarantula. Be warned though, it is incredibly geeky and does feature the line "until my face is bluer than a Haplopelma lividum' s legs!" No, me neither.
Still, from the article and the very helpful people on Bug Nation, it seems that the jury is currently out on the definite gender of Dot. The evidence points towards her being a her, but there is no definitive answer yet. I may still have to turn her name round the other way and start calling her Todd.
Tuesday, 13 July 2010
Who's afraid of whom?
Don't worry, no spiders (or people) were harmed in the taking of this photo. Dot the Chilean Rose Tarantula (Grammostola rosea) hadn't been eating much of late. It's apparently not unusual for captive spiders to go off their food, just like they could go for months in their natural desert environments without any prey. But it seems that there was another biological process at work here. Dot was moulting, shedding her skin. Many other animals including humans do this, except with humans its a bit more of a gradual process. Just like all arthropods (arachnids, insects, myriapods, crustaceans and the like) Dot has a tough exoskeleton. It's a good system really, instead of an internal skeleton like you and I have, arthropods keep their skeleton on the outside where it offers extra protection, like a suit of armour, as well as support. 
Except what happens when you want to grow? Well, you need a new suit of armour, which means you need to get rid of the old one first. This rather extreme form of moulting has to happen in arthropods because of this exoskeleton and is called ecdysis. It's a rather stressful experience for any creature, as you might imagine. They can also lose limbs in the process and are very vulnerable while they wait for their new skeleton to harden up. Thankfully, Dot's moult seems to have been a complete success.Dot also relies on her exoskeleton for feeding as well as defence. The sizable fangs you can see are certainly long and sharp enough to pierce human skin and deliver a painful bite, Dot (and all other spiders) doesn't want to do this, insofar as an invertebrate is capable of wanting anything, but that's another debate. Often when tarantulas and other spiders use their fangs in self-defence, they will "dry-bite" and not use any of their precious venom. Spiders cannot eat people, and so unless you threaten them they will basically ignore you. Spiders can only eat liquids, so use their fangs to inject a venom into their prey, digest its innards and suck out the tasty liquefied cricket, fly or whatever it may be. Their fangs are actually modified arms, and so are part of their exoskeleton meaning that they also become completely useless while she moults. That does mean that they will grow as she does. It also means that while she is still drying out, she won't be too hungry just yet, but I'm sure she will be soon.
And if you're still worrying about those fangs, then consider this: of the 40,000 species of spider currently recognised none are able to eat a mammal any larger than a small rodent, and only 7 species have ever been known to kill humans. Of those 7 the deadliest is thought to be the Brazilian Wandering Spider (Phoneutria spp.). Brazilain Wandering Spiders generally kill about 1% of people who are ever bitten. Who's afraid of whom?
Monday, 12 July 2010
Marjorie the stick insect
Marjorie is a Diapherodes gigantea which doesn't really seem to have a common UK name apart from the "Giant Lime Green Stick Insect." Which is a little bit uninspired.
As you might guess form the "gigantea" part of her Latin name, she has quite a lot more growing to do and should eventually be about as long as my outstretched hand and as thick as my thumb.
The swaying movement that she displays is thought to have two functions: Firstly, as I say in the video to Hayley, she sways in windy conditions to aid her camouflage, or crypsis as it is often called. Secondly, she is using the motion of her head to detect relative movement of near and far objects, parallax. This helps her perceive depth. Clever stuff!
As you might guess form the "gigantea" part of her Latin name, she has quite a lot more growing to do and should eventually be about as long as my outstretched hand and as thick as my thumb.
The swaying movement that she displays is thought to have two functions: Firstly, as I say in the video to Hayley, she sways in windy conditions to aid her camouflage, or crypsis as it is often called. Secondly, she is using the motion of her head to detect relative movement of near and far objects, parallax. This helps her perceive depth. Clever stuff!
Bug Explorers is Go!
Righty ho, first post. Blimey. Well, these pages are going to feature the bugs that I'm looking after - currently Dot the Chilean Rose Tarantula (Grammostola rosea) and several stick insects which are Macleay's Specters (Extatosoma tiaratum) and Diapherodes gigantea. There'll be lots of pictures of said beasties and the latest of what's happening in their world just as soon as I figure out how to put it all up...
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