Tuesday, 31 January 2017

Worlds Within Worlds

Do you want the good news or the bad news? The good news is that we’ve made it safely through the Milonas Gorge. The bad news is that we have a flipping great waterfall ahead of us which means we’ll have to find a way around and down and there are no paths to follow.

No matter, the sun is shining and there’s a flying circus in the sky. In case that seems a bit odd, forget the tents, clowns and performing seals and think of the origin of the word. Circus comes from the Greek kirkos meaning a circle or ring and was applied to a place of entertainment where the seats were arranged in a circle around the performing area. It is also the generic name of the birds that circle as they hunt which we know as Harriers. There have been four species recorded on Crete: the Marsh; Hen (or Northern); Pallid; and Montagu’s. The last three are rare and the Marsh, although a frequent passage migrant in the spring, only overwinters here in small numbers. It’s a bit too high to make out details but it’s still an exciting start to the day as it’s the first Harrier of any type that I’ve seen in these parts.

This really is an impressive bit of landscape with the lower valley stretched out before us and the great towering limestone cliffs at our backs. Hard to imagine that this was once a sea bed. Look up to that patch of blue sky and try to visualise yourself looking up to the surface of the ocean instead. That it may also once have been a tropical beach is easier to imagine because the evidence is here at our feet. The thing about limestone is that it is good at preserving fossils and we’ve got a smashing fossilized palm fan here. Pity it’s too heavy to lift, it would have looked nice by my fireside at home. Palm trees aren’t entirely tropical, there is one species (Phoenix theophrastii) that is native to Europe but there is only one authentic palm lined beach on the whole continent. Where? Crete of course, at a little place called Vai on the east coast. Remind me to take you there some time.

The water here is pushing its way around the rocks, trying to get to the head of the waterfall, which means that there are some intriguing little pools around. Let’s get a sample under the field microscope and see if there’s anyone at home. That little patch of algae clinging to the rock looks promising. Ooh look, an aquatic worm. There are three types of worm that you can find in pools like these. There are nematodes which thrash about frantically (you may remember that we found some three years ago down at Ferma rock pools – see Rockin' All Over The Shore); flatworms which glide around rather gracefully; and oligochaetes like this one which are rather squirmy wormies related to the common earthworm.

We seem to be making our way steadily downwards with loads of lichens, masses of mosses and cascades of chasmophytes (rock loving plants) lining our route but I see that we also have some lovely little yellow fungi down near our feet. Do you see that milky droplet exuding from the stem?  It looks like latex (but not the same latex that you find in plants) which is exuded by members of the milk cap family. However they exude latex from outside the mushroom not from the stem and there are no milk caps with this colour and habit so it’s a waxy cap like the ones we found in the gorge last week. Just when you thought fungi couldn’t get more confusing!

Hello, we’re into the jungle. It looks as though we’ll have to crawl through this bit. Still, while we’re down here we may as well have a look about and see what’s going on. How delightful, an ants’ nest, just what we need when we’re crawling along on our stomachs. But what’s this in the nest with them? You see the little orange insect trying to hide? It’s an Ant-loving Cricket (Myrmecophilus). Ants’ nests aren’t just for ants. They are like big cities and, just as with our cities, they have a diverse wildlife all of their own. Hundreds of different species have adapted to ant city life and this is just one of them. Absolutely tiny for a cricket, they never grow wings because they never leave the city, they’re deaf and mute and have very poor eyesight. They don’t have sex either, the females have virgin births, a process known as parthenogenesis. Doesn’t sound like much of a life but they seem to get by.

The Extra Bit

At last we’ve emerged into the open and even though we’re approaching midwinter a few of the flowers are beginning to emerge. We’ve got anemones, fumana, Cretan cistus and field marigolds all beginning to open their petals in the midwinter sun. If you look over there you can see the waterfall and that’s the direction in which we’ll be heading next week.

Thanks to JJ Wuilbaut at  Mediterranean Fungi for educating me on the difference between Waxy Caps and Milk Caps and to various members of Crete Birding for chatting about the various Harriers on Crete.

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Tuesday, 24 January 2017

The Milonas Gorge

I think that I may have lulled you into a false sense of security last week with all that beauty in Where Three Valleys Meet. Not that this week’s stage of the journey is any less beautiful but it will require a head for heights and nerves of steel in places. You have been warned! Those three mountain streams that were gently carving out valleys have now got together and their combined force has carved through the limestone like a knife through butter and we’re going to try and get through there. If you’re up for it, follow me.

Not surprisingly, as we enter this damp, almost subterranean gloom, we have fungi. The creamy brown jobs running up the length of this fallen tree are of the Crepidotus genus which is based upon the Greek for cracked ear. Many different species have been described in the past but modern phylogenetic analysis has shown that the same species can show different growth forms depending upon where they are growing. Essentially, like us humans, they can look very different but underneath they’re all the same. The gorgeous little yellow fellow is a wax cap of the Hygrocybe genus and these are rather unusual in that recent research has shown that they seem to have a symbiotic relationship with mosses and other bryophytes. As usual we are constantly discovering new ways in which elements of nature are working together.

I think we need to do a bit of climbing here. If you’d like to flip a few rocks I’m just going to shin up this overhanging pine and spy out our route. What have you got there? One grey and one orange woodlouse. Why? I believe that it is down to a genetic variation. The orange one, being more conspicuous, is more likely to be predated and so the grey form predominates. Did you know that the woodlouse is one of the true blue bloods of the animal world? Instead of having rich, red haemoglobin in their blood (see How To Get Blood Out Of A Stone) they have haemocycanin  that  uses copper to bind with oxygen instead of iron and their oxygenated blood is blue... um, you could have just taken my word for it.

We seem to have reached a little shelf where we can sit and catch our breath for a minute. Which is just as well as the next part looks a bit strenuous. The sea squills are just beginning to push their dark green leaves up from their bulbs and we have quite a swathe of little buttercups. We have over twenty species of buttercup on Crete and the distinctive leaves of these tell us that these particular ones are Ranunculus bullatus (subspecies cytheraeus if you want to be really precise). And where we have flowers we now have a beetle. These delightfully furry Tropinota flower chafers will be all over the place in a month or two’s time but this one seems to be taking advantage of an early harvest.

Now for the hairy bit. I did warn you but before we risk life and limb have you noticed the crag martins dancing through the gorge? You normally find them at this altitude and above but this winter I’ve seen them down by the beach. We always think of bird migration as a long distance affair but some birds are mini migrators – just a few kilometres north to south or from higher to lower altitudes.  Rock thrushes and even ravens tend to move down from the mountains in cold weather round here whereas white wagtails move up from the beaches where they bum around in the summer and head for the shelter of the olive groves. If you’re ready we’ll crawl along this little ledge and then scramble our way to the top. My, but it’s a long way down. I’m not sure that your humming the theme from Indiana Jones in my ear is helping.

The Extra Bit

You have to admit that the view from the top was worth the knee-trembling climb. The whole of the lower valley stretched out before us. All we have to do now is find a way to get down there.

I'll be popping back and forth between Crete and Athens over the next few weeks so please bear with me if I'm a bit slow in answering your correspondence. SD

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The Nature of Crete  (Flipboard Magazine)

Tuesday, 17 January 2017

Where Three Valleys Meet

Let me take you by the hand
To a far and distant land
Where peace and tranquility reign
Where bare winter branches
Form cathedral like arches

And the earth smells of soft winter rain

Where an old olive tree
Beckons quietly to me
Indicating the route I should take
And a bubbling rill
Is beginning to fill
With leaves floating down in her wake

Where silver branched thyme
Beneath redolent pine
Seductively draws me along
As I potter and dawdle
And the warblers warble
Filling the sky with their song

Turning damp logs
And searching for frogs
A scorpion hides from the light
Dreaming her dreams
Or that’s how it seems
As she waits for the falling of night

To where solid rock walls
Cause the water to fall
Amidst lichens of yellow and blue
And a kingfisher darts
As I say from the heart
That the only thing missing
Is you

The Extra Bit

After all the physics, biology and chemistry of the past few weeks I thought I’d give you a bit of a rest with this piece of doggerel. Sometimes, in our close examination of the natural world, we can overlook the sheer beauty of our surroundings. If you’re still looking for a New Years resolution for 2017 (or the original has already fallen by the wayside) then I’d recommend an hour or two each week just being at one with nature. There’s nothing quite like it for recharging the batteries and pushing the everyday niggles of modern life into the background.

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The Nature of Crete  (Flipboard Magazine)

Tuesday, 10 January 2017

Inside The Rainbow

A rainbow over Agios Ioannis
I see that you’ve got your wet weather gear on this morning which is just as well looking at those clouds covering the mountains. I’m not sure we’ll get down to where three valleys meet but never mind; seeing that beautiful rainbow pouring itself into the village of Agios Ioannis gives me an idea. We’ll see if we can find all the colours of the rainbow reflected in nature. I say ‘reflected’ advisedly for the colours that we see are mere reflections which we should be able to illustrate as we go along but first, have you ever stopped to consider how we perceive colour? It’s all down to cone cells in our eyes. Back in 1672 Sir Isaac Newton first discovered that light was made up of different colours when he recreated a rainbow with a prism. If you could slow light down you could see that it came in waves, like the sea crashing onto the shore, but whereas the distance between the crests of the waves in the sea may be several metres or more, waves of light are infinitely smaller (about 4-7 ten millionths of a metre) and the different colours have different wave lengths. This is where the cones come in. We have three different sizes: one for catching the longer red, orange and yellow wavelengths; one for the medium green; and one for the smaller blues, indigo and violets. These send electrical signals to the rest of the brain telling how much of each they’ve collected and the brain then combines these signals, like an artist with a palette, to give us the colours that we visualise. 

Why do leaves change colour?
Let’s see if we can give the big cones some exercise and find some reds, oranges and yellows. If you’ve ever wondered why leaves change colour at the end of the summer it’s because they’ve stopped photosynthesizing. During photosynthesis they use all of the energy in the light waves to produce sugars with the exception of the middle green wavelengths which they reflect back. Hence we see plants as green. As light levels decrease in the darker months they shut down photosynthesis and the green reflecting chlorophyll is broken down and reabsorbed into the roots for use in the spring. The unwanted parts of the leaves now reflect the long wavelengths of red, orange and yellow back at us. Now these little fungi (Calocera cornea) don’t photosynthesize and their colour comes from the nutrients that they absorb from the soil. They still use light to process these nutrients efficiently (except the yellow wavelengths) as scientists found out when they grew some of their relatives in the dark. They didn’t grow nearly so well and were completely devoid of colour.

Why is moss green?
Last week we were looking at some bryophytes (mosses, liverworts and hornworts) and we have some more here on this rock. If you remember the gametophytes – the green leafy bits that sexually reproduce – give birth to the sporophytes which reproduce asexually. Now, from the colour you can see that the gametophytes, like other plants, use chlorophyll to photosynthesize but the sporophytes, which appear brown, obviously don’t. The question is; where do they get their food from? And the answer is; they sponge off their parents. The sporophytes remain attached to the gametophytes for their entire life cycle. They do make some contribution to the household budget however. As you can see they are quite good at collecting water droplets.

Why is the sky blue?
I think that we’re going to have a bit of trouble getting down into the valley from here. We’ve walked to within view of the Milonas Gorge and there still seems to be no route to the bottom. A lovely view of the sea and sky though from up here.  And here comes the answer to the age old puzzler often asked by children: why is the sky blue? Simply, as the light passes through the atmosphere it collides with the oxygen and nitrogen molecules (see Every Breath You Take). This doesn’t affect the longer wavelengths much but the shorter wavelengths get scattered and wherever you look you are seeing this scattered blue light which comes at you from all directions. The large and medium cones are receiving red to green in one direction only but the small cones are receiving blue to indigo from everywhere and so the brain concludes that the sky must be blue. It’s totally wrong of course, the sky contains all the wavelengths of light and is in fact white.

Why are some leaves indigo/violet?
The indigo violet hues on the underside of this Oxalis leaf are a bit of a puzzle. The reason that some plants have leaves of this colour, top and bottom, is due to the preponderance of chemicals called anthocyanins that help to protect the plant against overexposure to ultraviolet wavelengths (even shorter than violet and too small for our cones – we cannot see in the ultraviolet but some animals can). Anthocyanins are present in most plants but they outweigh the chlorophyll in indigo violet plants. They absorb the green wavelengths but aren’t so good with other wavelengths that they reflect back to us. Why the underside of this oxalis leaf contains so many anthocyanins (or conversely so little chlorophyll) is the mystery. If you take a look under the other Oxalis leaves nearby they’re a regular green. My guess is that the genes that program the underside of the leaf to make chloroplasts (that manufacture the chlorophyll) aren’t working. A genetic mutation in other words. In theory, if this confers an evolutionary advantage, such as animals preferring to eat the all green leaves of the other plants, then the mutants would survive and all Oxalis would have undersides this colour eventually. We could be watching evolution in action (if I hadn’t plucked the leaf to show it to you).

I promise not to destroy the environment  so much next week.

The Extra Bit

If you look back over your shoulder to where we started out a few weeks back there’s a lovely view of the mountains covered with snow (which scatters all the wavelengths to such a degree that we see it as white). 

For more detail on how we see colour this is a good article: 

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Tuesday, 3 January 2017

Water Divining

The winter rains have started in earnest and our gullies should be starting to fill nicely now. There is an ancient practice called dowsing whereby you can divine the presence of water by wandering about with a Y shaped stick. Whether this actually works or is merely some sort of ideomotor effect where an action is prompted by the subconscious is open to debate. I prefer to use a simpler technique: walk downhill and when down changes to up that is where you’ll find water if there is any. So the water should be down there somewhere. Just before we start our descent take a look at these harvester ants down here who seem to be having a bit of a problem. Falling olives can be a nuisance. At this time of the year my courtyard is littered with them and they get trodden into the house and make a right old mess. As yet, I have never had one fall and totally block my front door. It would be interesting to stop and watch how the ants solve this particular dilemma but it’s a bit chilly this morning for hanging about so we’ll press on.

It looks as though we’re getting close to the bottom now but before you go diving in have you noticed these little moths that we’ve been disturbing as we walk through the undergrowth? These are Diamondback moths and although they’re tiny they’re very interesting. For a start, despite their size and the fact that they only fly as adults for about a fortnight they’re marvellous at migration. It’s a European moth that made its way to America in the nineteenth century and has now turned up in the Hawaiian Islands. It also loves cabbages and is the nemesis of commercial brassica growers. A group of European scientists have found a chink in its armour however. They found that given the choice, the moths would prefer to lay their eggs on Yellow Rocket (Barbarea vulgaris) even though their caterpillars couldn’t eat the stuff and died. Weird but true. This one presumably is not laying eggs at the moment as it is on a mallow leaf and unlike cabbages and rocket, mallow is not part of the Brassicaceae family which is the only family on which Diamondback Moths will lay their eggs (even if they sometimes get the genus wrong).

OK, time to get down and dirty and dive into the gully. Great, we have water and with it what appears to be a covering of Moss on the rocks. But they could be Hornworts or Liverworts. All three are popularly (but incorrectly) lumped together as bryophytes and they share a similar but interesting way of going about life. Firstly, distinct male and female bits develop from spores (those are the green leafy bits which are called gametophytes). The sperm from the males swim to the eggs in the female; hence you find ‘bryophytes’ in wet, or leastways damp, places. These gametophytes then give birth to something completely different called a sporophyte (which is the stalky bit with the capsule on top). Sporophytes don’t muck about with the sperm and egg method of reproduction but go for the asexual method of producing spores which then develop into gametophytes and the cycle goes round again. It’s a bit like humans giving birth to a generation of mushrooms that then give birth to a generation of humans again. Sex is really weird down at this level.

Our next descent looks a bit tricky; a twenty foot slide down into a pile of branches that look to be hiding something akin to a tiger trap. What say you that we just take a look at these little orange fungi that I’ve just spotted on this wet wood and then find a less adventurous route down? These are called Scutellinia scutella by mycologists which is rather boringly from the Latin meaning little shield. I much prefer the common names for them which include Scarlet Elf Cap, Eyelash Pixie Cup and the delightful Molly Eye-winker. The last two are on account of the small hairs on the outside which look a bit like eye lashes. Here, have a look through the hand lens. Pretty little things; you can just imagine the little elves tripping around here at night by the light of their Jack o’lanterns and trying them on for size. I think the place is beginning to get to me, let’s get up into the real world again.

That’s better, back in the world of what you see is what you get. Only not quite. That bee pollinating the white mustard down there isn’t quite as it appears. Look closely at the pollen sacs – there aren’t any. And those eyes look a bit too close together and meet at the top which is a bit odd for a honey bee. And do I detect only one pair of true wings and rather short antennae? I do believe that we have unmasked an impostor. This is no bee collecting honey for the hive; it’s a fly, cunningly disguised, nonchalantly sipping nectar secure in the knowledge that his livery will protect him from predators. A lovely bit of visual crypsis where one insect has evolved to resemble an entirely different insect purely by natural selection.  Back in its ancestral lineage the flies that looked a bit like bees were less likely to be eaten than those that looked more like flies and so the bee look-alikes survived to breed more look-alikes. The more their offspring looked like bees the more they survived to breed until now they are almost indistinguishable from the real thing.

We seem to be approaching the point where other small valleys are coming in to join our main valley so, with a bit of luck, we’ll have even more water to splash about in next week. See you then.

The Extra Bit

A question to my friends in Northern Europe: What have you done with my moths? December has come and gone and my terrace wall should be a teeming metropolis beneath the light. So far I’ve seen nothing more than the odd noctuid and pug. Have they stopped migrating?

Naturalists (the facebook page that accompanies this blog)
See detailed pictures at http://www.inaturalist.org/login  (search - people-stevedaniels-observations)
The Nature of Crete  (Flipboard Magazine)



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