Tuesday, March 27, 2012

Spiders have their skeletons on the outside...

Since my journey into macro photography began, some years ago now, there have been quite a few asides to the actual business of taking photos.
One of these has been that my innate fear of spiders has lessened with the knowledge that has come from photographing and researching them.

I've only scratched the surface of course of what could be attained regards information on these critters, but all the same, I've come to realise that they are fascinating creatures and have an important place in our ecology.

I suppose that one of the most amazing revelations has been that spiders moult. I had always assumed that thing hanging motionless in the corner of the garden shed, just under the ceiling, was a dead spider, but no, not so.

I remember as a child seeing the remains of 'Pholcus phalangioides' the Cellar Spider hanging in the outside loo and thinking the same. It hadn't occurred to me that it was nothing of the kind but was actually a moult.

And so it came as quite a shock to me when I found and photographed my first spider-moult.

A Spider's Exoskeleton
The correct term for what you see here is an exoskeleton and put basically, it's a stiff support structure on the outside of the body.

Like we do, spiders move by contracting muscles attached to their skeleton. The way in which they differ from us is that their skeleton is on the outside. Exoskeleton segments are connected together with joints so that the spider can move them back and forth.

The skeleton is made up of several layers of cuticle,plus various proteins and chitin. These are arranged in long chains and layers a bit like plywood.

This structure makes the cuticle very strong, as well as highly effective at keeping the spider from drying out, but the material does have one serious drawback. Whilst it's flexible enough for movement, it can't expand like human bones and tissue:in other words it can't grow. In order to increase its size, the spider has to form a new, larger cuticle exoskeleton and shed its old one.

Moulting occurs frequently when a spider is young, and some spiders may continue to moult throughout their life. At the appropriate time, hormones tell the spider's body to absorb some of the lower cuticle layer in the exoskeleton and begin secreting cuticle material to form the new exoskeleton.
To shed the old exoskeleton, the spider has to burst out from the inside: it increases its heartrate to pump a lot of hemolymph (spider blood) from the abdomen into the cephalothorax. The pressure expands the cephalothorax, which pushes on the old exoskeleton until it cracks. The spider then flexes its muscles until the old exoskeleton falls away.

I'd like to apologise here for the amount of text in this particular blog-entry, and now ironically, I've added to it by typing this, and so I'd better apologise for doing that as well.
Sometimes it's required to tell a story though and I felt that it would be uninteresting and dull to just add photos with little or no explanation or reason.

Today I found a spider that had freshly moulted. In fact, it was so fresh that you can see in the picture below that the cephalothorax is still very soft and misshapen.

Click on any photo for a larger view.
An Orb-Weaver Spider moulting

This was an exciting find as I've never witnessed this before and it completes another piece of the jigsaw regards spider behaviour for me. Here's another view; this time from below. I was struck by the markings underneath the spider that make it appear to have eyes-it almost looks like a tiny octopus here, especially with the right amount of legs.

Typically, the spider does most of its growing immediately after losing the old exoskeleton, while the new one is highly flexible. The new exoskeleton is also very soft at this stage. making the spider venerable to attack. You can see from the photo above how lifeless the body looks at this stage.

Many species will lower themselves on a silk line during the moulting process, so they're out of reach of predators while the cuticle material hardens. This orb-weaver is just about to do that very thing in the photo above.

It was a real treat to see this today and I hope that I've not rambled on too much here. I wanted to share this event so that you too can marvel at nature's ingenuity as I have.

Util the next time then...

Tuesday, March 20, 2012

Bee-flies at dawn...

The thing about having an interest in invertebrates is that you do need to actively look for the bugs and insects.Even then, sometimes it pays to take a second look at something that at first glance seems uninteresting.

Yesterday, towards the end of the day I was ambling along past a local pond, keeping an eye out for a kingfisher that I've seen there recently, when I noticed that something looked odd about a bud on the branch of a tree as I passed.

Only half-interested, I dismissed it and walked on:but knowing that it's often a closer look that reveals anything that might be there,it nagged at me.
"Go back and have a look" the voice in my head kept saying. "Can't be bothered"    said the other voice! (Don't ask, I have lots of voices in my head all the time-it's rarely quiet in there) And then I found myself stopping and turning back before the second voice had time to complain again.

Anyhow, the internal fighting was all worthwhile on this occasion because had I not taken another look I would not have learned what I now know.
The whole point of this blog is to share these things and so that's what I'd better do....cue first photo!

Bombylius major

And so what you might be thinking is so interesting about this particular photograph?
Well, this is what the 'bud' turned out to be on closer inspection. These bee-flies are a common sight in spring but until now I've  not seen them anywhere other than at flowers nectering, or sunbathing on warm stones etc.

Then there's the additional fact that I've learnt from past experiences that these insects do not usually hang around waiting to have their photograph taken.
I began to wonder then if this one was 'roosting' for the night? A lot of insects will sit out the hours of darkness, motionless until the sun warms/dries them enough to take flight again.I'd not heard of bee-flies doing this and so it would be new information to me if it turned out that I was right.

I reasoned that if it was displaying this behaviour, then an early morning visit would be in order for today with the chances of it being in the same spot pretty high. I took another shot from the other side and made a mental note of just which tree it was on and tied a length of grass around the branch in question to make locating it easier today.

I was hoping that today would start with damp conditions and I'd find the bee-fly covered in dew-I've photographed other insects in this condition and it makes for an interesting shot. However, it was not to be and when I rose at 5.30am it was obvious that there had actually been a frost.
Would my insect be there now? Would it have survived the harsh conditions out in the open as it was? (Stay with me, this is what's called the 'Teaser' in T.V. terms, I'm trying to build the excitement.) Before I would have my answer, there was another little chore that needed to be done:as I strolled towards the area in question it started to dawn on me (do you see what I did there? Dawn on me!...Ahem!) that there could be a lovely sunrise and it looked fairly imminent too.

I'd hardly got the camera set up before an area beyond the trees to the east of me, began to exhibit amazing hues of red, orange and gold that looked like there had been some kind of weird accident in heaven and the angels were bleeding all over the sky. (That's from a confirmed humanist too!).

I couldn't resist...

Just for a moment it was almost overwhelming-the sky was ablaze, there was that early-spring chill in the air, the only sound to be heard was the skylarks  singing overhead and I still had the main event ahead of me.
The sunrise, as beautiful as it was faded in no time at all though and my thoughts returned to the little bee-fly:would it still be there?

I easily located the tree and then correct branch and there it was, success! Not only a treat to see but confirmation of something I'd previously had no idea happened. That's what I love about bug-hunting, there's always something new to learn.The only thing I noticed was that it had moved down the branch a little overnight.
The following few photographs are the ones I shot this morning at around 7am. I tried to make them as interesting and artistic as possible by getting the glow of the sunrise behind the insect, I hope you like them.


A male Bee-Fly

I had a hunt around for some further information about this behaviour and managed to put together a few interesting bits of research.
Those who have studied these insects in much more detail than I have found that some of the species will fly along the ground to absorb heat, whilst others fly further up tress to maximise direct heat.

When cold (at night for instance) they will perch vertically, pointing upwards, and they can remain in this position for a week or even longer.
They will then whirr their wings to warm up the flight muscles before take off.
I haven't yet found a definitive answer as to why some are paler with white areas, as this one is. The only plausible answer could be that the ones that emerge early seem to be lighter. I'm not sure I would go along with that myself as I've photographed these lighter coloured ones later in the year.

The adult males exhibit courtship rituals - they hover at height and exhibit territorial behaviour which includes darting at rival males and spinning at females.

That's about it for bee-flies then, I hope you've found it at least half as interesting as I have?

Until the next time then...

Friday, March 16, 2012

Spring, Spring,spring...

Things are really starting to hot up here in Kent now, over the past week we have had some reasonable temperatures and I have spotted a good number of invertebrates.
Just today I saw Small Tortoiseshell and Comma Butterflies as well as Honey Bees, Bumble Bees and Hoverflies.

I've also been seeing a few species of weevil starting to emerge.

Curculionidae Weevil
I'm not sure of the exact species of the weevil pictured here but think it probably belongs to the Curculionidae family.

A little background:
Curculionidae is the family of the 'true' weevils and is the largest of any of the animal families with over 40.000 species described worldwide. These weevils are quite diverse and can range in size from 1-40mm.

The warmer weather has also encouraged out the little jumping spiders...

Salticus scenicus-A Jumping Spider

This picture was a real challenge to get. It's made up of several shots that have then been combined (stacked) to comprise the final image. As this was a live spider there was inevitably a bit of movement of the legs (well, when you have eight, it's difficult to keep them all still.) There was also some movement of the camera (my fault) and so the software used to combine the images had to work hard to produce the end result.

The picture(s) below show the timeline of the images as they were shot, if you look closely you can see the movement I mentioned. The reason for the difference in colour of the final image is just that I decided to correct the ISO settings for a more natural look.

The next photograph is one that I've cribbed from my flickr photostream. It's an extreme close-up of the same species of spider.

I explained on flickr that this was the result of an experiment and that I'd post details here. So here goes...

For this shot I used a 28mm film camera lens reverse mounted to around 100mm of extension tube. I'd recalled a while ago one of my flickr contacts explaining about  multi-shot images taken by setting the camera to high speed/continuous mode as a means of getting several images to stack.

That's what I decided to try:I experimented with several ways of doing it but basically, I just set the camera on to a macro rail and held the shutter button in whilst I carefully pushed the camera slowly towards the spider. It took several tries to get anything worth saving at all but when I viewed this particular set of images, I was pleasantly surprised at how well they came out.

It's not however something I'd recommend: at least, not the way I did it. It's both time consuming and very hit & miss.I think I was just lucky here.

Bombylius major-A Bee-fly
I'd seen my first Bee-fly of the season a couple of days ago. Today though, as I stood beside a bramble patch, watching a comma butterfly basking in the sunshine, something caught my eye.
Stuck in the remains of a spider's web was this very damp and very deceased, bee-fly. I'm not sure exactly what happened to it, whether the spider was responsible or not but I decided to rescue it from the web and take a few close up shots as these are not that easy to get close to normally.

I dusted it down best I could and took a few photos of which this is one.

Bee-flies look menacing with the long proboscis but are actually quite harmless. If you hear a high-pitched whine close to low growing flowers, chances are it'll be a bee-fly. I always think of these as real harbingers of spring.

Entry from my diary for Friday March 9th:
Every morning I check on the caterpillars that I've been trying to raise at home as an aid to increasing my knowledge of species and their behaviour. Today, unexpectedly I was greeted with the sight of one having pupated.

 Moth pupa

Friday March 16th:
I didn't get to check on my caterpillars this morning until around 9am. When I did it was something of a shock that overnight this pupa had become a beautiful moth. I knew of course that this species over-winters as larvae but hadn't appreciated just how short the pupal stage is:a mere 7 days in this case.

Phlogophora meticulosa-The Angle Shades Moth
This fantastic, night flying moth belongs to the Noctuidae family and it's pattern varies quite a bit but tries to give the impression of dead, dried leaves when it's at rest.
It feeds on a variety of plants and is quite common in woodland,gardens and even urban areas.

As these are night-flyers, I found a safe and secluded part of the garden to put this one in until nightfall. Before doing so, I couldn't resist having the opportunity to take some further shots knowing that it wasn't about to disappear.

A real treat to see this little one fresh as a daisy and ready to go.I'm already looking forward to seeing what emerges from the next pupa.

Whilst in the garden on full 'bug-alert' recently, I came across this creature...

A Bark-fly
This tiny thing (less than 5mm) is a bark-fly or louse and belongs in the Psocoptera family. It rejoices in the name of Pteroxanium kelloggi and not a lot seems to be known about these little ones as this is only the second record of finds in my area, and I made the last one! No doubt under-recorded as so many bugs are.

Asellus aquaticus
Whilst we are on the subject of lice...this charming creature pictured above is a common freshwater louse. Again, these are common in many ponds and streams and are quite like the woodlouse in appearance.These feed on organic matter in the sediment and are about 15mm long.

Quite a mixed bag for this blog entry as you might expect as spring takes hold. I'll be back with you soon and who knows what the next entry will feature-I certainly don't!

Until the next time then...

Wednesday, March 07, 2012

A few faux friends...

It's been a while since I could get out and take a few photos of the local wildlife and nature etc.. but finally the weather relented and time allowed a few hours wandering around the Kent countryside.

First up is this Rove Beetle photo from a couple of days ago.

Paederus littoralis

This little beetle is only about 7 or 8mm long and is flightless.It belongs to the family 'Staphylinidae' There are nearly 1,000 species here in the U.K. some of which have a resemblance to earwigs.
This particular photograph was taken using natural light and is a stack of a few images. This one I rescued from a cattle trough that it had fallen into, it was not at all well following it's ordeal and probably the only reason that I managed a few shots before it scurried off. It did recover though and was soon on it's way. Below is an image from a week or so ago that shows a whole beetle and was taken using flash.

March in the U.K. is right at the tail end of winter, but not exactly spring yet and although bugs and insects are starting to appear numbers are small as are species. However, you only need to turn over a few stones, or fallen branches, or even pick up a handful of leaf-litter and chances are there will be something of interest.

A Click Beetle

This fantastic little click beetle was found in exactly that way, I picked up a large stone to see what if anything was lurking underneath, when this dropped off. The colourful thing it's perched on here is just a small bit of card that I used to pick it up with to get a photograph; before replacing it under the stone to sleep out the remaining days until the temperature rises enough for it to get out and about.

These are always nice to find and their 'coats' always remind me of a pasta that's been squeezed in that area just behind the head/thorax. Just me then?

Moving on.....

A Ground Bug-Scolopostethus sp.

This tiny ground bug belongs to the family 'Lygaeidae' and is only around 4mm in size. These are notoriously difficult to i.d. with any certainty from a photograph but I think I have this one right, at least down to species level.
Once again, this little bug was revealed to me when I turned over a piece of fallen bark and although it was good to see a true-bug after a long winter, it's true colours are only revealed by photographing it with the macro lens; it would just be too small for the human eye to pick up all the detail. Well, my human eye anyhow.

A False-Ladybird Larva

Some days can be particularly frustrating when out bug-hunting and those days have been to the fore over the past few weeks:to be fair, I'd expect little else through the winter months. But this day was turning into one of those rewarding ones when it all seems worthwhile and the finds were starting to get very interesting.

I decided on checking out an area beside a local crop field where I knew there was a fallen tree and that meant a good opportunity to search under the now lifting bark for further invertebrates.

Thinking I might just spot some interesting collembola species I began to search. Nothing of interest, just the usual suspects. I'd almost resigned myself to it being a lost cause when I found another of these fascinating beetle larva.
I found these for the first time only a few weeks ago but this time I had the idea of taking a couple home (I eventually located around a dozen or more) to see if I could observe them pupating and then emerging as adult beetles later in the year.

And so now I have a nice container that replicates their natural surroundings as closely as possible and I'm hoping that I'll be able to watch their progress and learn a lot in the process.

A False Scorpion

Under the very same piece of bark where I found the ground bug was this fantastic creature: a pseudoscorpion. As I think I've stated before on this blog, these are so called because of their resemblance to scorpions. They actually have no sting and as for size, the largest are only 8mm with this one being a mere 3mm, smaller than the ground bug.

They may pose no danger to us but if you're an insect then beware;these tigers of the undergrowth can produce a venom that is extremely toxic and is more than capable of felling prey several times their own size.

These pseudo or false scorpions are actually arachnids. There is an interesting piece with further information about them here.

I ought to point out that the i.d. I am providing on these insects is purely based on my research and sometimes the help of like-minded friends. I am not an entomologist, just an interested amateur photographer and so if any prove to be incorrect, I apologise and would welcome corrections.

Litargus connexus 

The two photos above of a 'Hairy Fungus Beetle' are an example of my inability to put an identity to some of my finds and having to resort to requesting help from others with better knowledge of such things.

I'd not even got to species level with this one when I began to suspect that I might need help. I decided that my best plan of attack would be to enlist the help of someone that had helped me numerous times in the past and so I fired off an email with pictures of the beast to Tim Ransom and in no time at all back came the answer in full. Even better, the added information that this little beetle had last been recorded in my area in 1991 and so it turns out to be a nice find.

Carabidae-Leistus species (possibly L.spinibarbis?)

This striking blue beetle of the Carabidae family had me hurriedly adjusting my flash settings on the camera to try and obviate the reflections from the metallic elytra as best I could.

These fast running beetles are essentially carnivorous, feeding on a variety of other invertebrates.Many of them have this bright, metallic look and can be Bronze, Green, Violet and even in the case of the strange Tiger Beetle, spotted!

Phragmatobia fuliginosa

My last find of the day was this Ruby Tiger Moth larva. These are known to feed on herbaceous plants but I think this one was still in it's dormant phase.

They do morph into a spectacular moth that can be seen flying  from April to June and then again from August to September, although I understand there is just one generation in the north of the country.

A Ruby Tiger Moth

That, ladies and gentlemen, concludes this edition of my little nature/photography blog. I hope you'll be able to join me again soon for the next? Many thanks to everyone that has signed up for notifications of new blog entries and my friends around the world that I know read these missives also. Special thanks to my friend Tim Ransom for his invaluable help with i.d. on some of these entries.

Until the next time then...