A Recipe For Life

We seem to have taken quite a detour last week to get down to this level and the waterfall should be over there somewhere. We’ll follow our ears and get there somehow but first, that looks interesting. There’s probably a correct technical term for these shallow erosions but I just call them cavelets. Let’s climb up and take a look. As you can see from the staining of the rock face, water is leaching minerals from the rocks and if you look up there you can see small stalactites forming. There are also white deposits blooming on the walls which my geologist friends tell me is probably gypsum/selenite.  They contain calcium and sulphur so, along with the limestone rocks which contain calcium and carbon, and the water, we have carbon, oxygen, and hydrogen (the basic elements of life) plus at least a couple of others to add to the recipe. We’ll push our way up through these bushes using this tumbling water course as our stairs and see what’s going on.

And up here, below the dripping stalactite, if you look carefully you can just see some threads of green algae forming. There’s a whole world of wonder in this little splash pool which began when large molecules of dissolved organic substances from the stalactite attached themselves to the wet rock. These neutralised the electrical charge of the water surface and allowed bacteria to colonise and they, in turn, secreted sticky strands that formed a nutrient trapping matrix. This matrix, known as the biofilm to periphytologists (people who study slimy rocks – yes, there really are such people), then served as a base for more bacteria to expand and diversify the biofilm and then for our green algae to grow. The algae, in its turn, will provide a home for microscopic life forms such as the ciliate we found in Life In The Olive Grove .

Algae are very basic life forms but we also have some higher forms of plant life up here. These fig branches, tenaciously clinging to the underside of this crack are just coming into bud and down in the damp crevices we have some lip ferns whilst out on the dry, stony ground, the beautiful but dangerous mandrakes are coming into flower. Their relative simplicity or complexity is reflected in their evolution: the flowering plants which include the fig and mandrake have been with us for about 120 million years, the ferns about 320 million years and the green algae maybe as long as 500 million years. Us? Well, as primates about 55 million years but as Homo sapiens only a couple of hundred thousand years.

Have you noticed these cottony threads in amongst the berries of this lentisc bush here? Alongside the evolution of plants came the evolution of insects and these threads look like the work of woolly aphids. Pass me the field microscope and I’ll see if I can find one for you. There’s one look, if you study him closely you can see him sucking up the sap from the plant. And where there are insects there are predators; there’s a minute spider that has his eye on stuffed aphid for lunch. Talking of which, let’s see if we can find some cave spiders lurking in the deeper recesses.

Do you think that you can wedge yourself up into that crack and see if there’s anyone about? Plenty of webs? That’s a good sign. You’ve found one? Good, I’ll squeeze in beside you and take a look. Hmm. It’s not a cave spider but he is rather interesting. Do you remember me telling you that you don’t have to worry about spiders in Crete because we only have one venomous one and you’re unlikely to come across it? Guess what? You’ve found one. Sorry, probably not the best time to impart that information when you’re perched precariously thirty metres up a cliff face, but don’t worry they’re pretty shy creatures and he won’t bother you unless you threaten him. All the same I think we’ll climb down. That was a Mediterranean Recluse Spider and although his bite can cause nasty skin lesions, a condition known as loxoscelism for which there’s no known treatment, it is rarely fatal. Having said that, there was a fatality last year in Italy but I believe that the unfortunate victim was already suffering from some sort of immune deficiency, which would have been a contributing factor.

Still, venomous spiders aside, a pleasant little diversion and a different angle from which to look at this wonderful thing called life. Now how are we going to get down from here?

The Extra Bit

Last week I glibly said that there is “only one authentic palm lined beach on the whole continent [of Europe]” and that was at Vai on the east coast of Crete. I am indebted to Jackie Strasis for reminding me that Phoenix theophrasti also lines Preveli Beach in southern Crete and I have also learnt that there are yet more at Ayios Nikitas in Heraklion Prefecture. Further research has turned up one other native European palm, The Mediterranean Dwarf palm, Chamaerops humilis, which lives in south west Europe. Just goes to show – you can’t believe a word that I say. Thanks for correcting me Jackie.

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LINKS:

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)

Cretan Flora

Flowers of Crete;

BIRDS OF CRETE

Crete Birding

Greek Butterflies and Moths

Aquaworld Aquarium

Visit Greece (National Government Tourist Office)

Fruits of Autumn

The vernal equinox has passed and it’s time we got down to some serious exploring after all our loafing about at the Porto Belissario for the last two weeks. We spent the earlier part of the year to the west of the village, predominantly in the Milonas Valley, so let us strike out east and see what we can find.

Plants have many methods of seed dispersal

It’s a beautiful early morning and just look at how the sun is catching the sandstone giving it a rich, golden glow. Many of the plants, like this lentisc or mastic bush, are throwing out their fruits just now, which is the equivalent of animals having babies. It’s a similar process involving eggs and sperm but somewhat more complex as flowering plants undergo double fertilization; the first producing the seed and the second producing the surrounding food storage tissue which nourishes the seed during development. So when you eat a grape and spit out the pip you are consuming part one of the process and ejecting the second. This is just what the grapevine wants you to do as by the time the grape is sweet enough to eat the seed has developed sufficiently to start an independent life and you are merely the chosen agent of seed dispersal (ever felt you were being used?). Some plants, like this Greek Spiny Spurge, positively explode their seeds away from the parent plant like ejecting a stay-at-home teenager from the family home with a cannon while these cistus plants on the other hand just drop their seeds where they fall. This seems a strange thing to do but the plants are full of volatile oils and burn easily in a wildfire. The seeds are cunningly designed to germinate after such a fire. 

Spotted Flycatcher, Muscicapa striata

Many bird species are involved in the dispersal of plant seeds as well being great consumers of berries but not so this little fellow perching, guardsman straight, on the telephone wire. He’s a spotted flycatcher and, as his name suggests, his diet consists mainly of flying insects such as flies, beetles and wasps. These birds pass through on their way from northern Europe to Africa between August and October returning between mid April and mid May although I have seen the odd straggler in February and March who didn’t see the necessity to go any further south. He’s watching that patch of open scrub down there so let’s go down and see if we can disturb a few insects for him.

Grasshopper habitat

Watch the stones here they’re looooooooooose. Well, that’s a new personal best – pitched onto my posterior within the first half hour of our first hike. However, not without waste, there’s a nice little grasshopper down here. Magnificent little animals, grasshoppers, they can jump twenty times their own body length and pull twenty gees when they take off. How they do this involves a clever bit of mechanics. When we jump we use muscles in our upper and lower legs that extend and contract and the world record for the long jump is around five body lengths. Grasshoppers get four times this distance by using a special pennate extensor muscle in the lower leg that can store energy like an elastic band. When it jumps it stores and releases this energy in less than half a second and catapults itself into the air. There he goes…boing!

Slime mould, Arcyria nutans

We’ll make our way across this bit of scrub and head for those pines over there. Plenty more grasshoppers pinging their way from under our feet, mainly red wings as far as I can see. The huge jump is a defence mechanism of course and that flash of orange from the underwing is another one – it aims to startle and confuse predators. Quite a few dragonflies darting around; the flycatcher should have a decent breakfast. Ah, what have we here – a rotting pine branch. Let’s see who’s at home. Quite a number of holes and tunnels, probably made by beetle larvae, but otherwise about as lively as the Marie Celeste. We do have an interesting slime mould though. The words slime and mould tend to conjure up rather revolting images in the mind but this one is rather pretty. We’ll put the log back as these little life forms have the same aversion to light as Count Dracula and the sun is getting a little on the strong side now. I suggest we try and find a route down to the sea and cool ourselves off a bit.

 

Sea Cucumber, Holothuria foskali

Ah, that’s better. Quite a nice little reef, I wonder what’s sheltering in the cracks and crevices? This is a nice find, it’s a sea cucumber. Superb animals that do a great job recycling nutrients on the sea bed, rather like worms do in the soil. Pity they’ve become such a delicacy on the Asian menu. Back in the 1950s we more or less left them alone, these days we’re harvesting 16,000 tonnes of them a year and in places where we’ve stripped the sea bed of them completely we’ve made it totally uninhabitable for other organisms¹. Not that they are without defences; this one, as you can see, squirts sticky filaments at its attacker – in this case me and if I hadn’t moved sharpish I’d have spent the rest of the morning trying to get the stuff off of my hand and camera. I love reef snorkelling; you never know who you’re going to meet next.

Until next week – happy hunting.

1 Living Blue Planet Report - August 2015

See all the pictures including insets in detail on Flickr

Crete Nature Blog is sponsored by:

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LINKS:

Naturalists (the facebook page that accompanies this blog)

Cretan Flora

Flowers of Crete;

BIRDS OF CRETE

Crete Birding

Greek Butterflies and Moths

Aquaworld Aquarium

Visit Greece (National Government Tourist Office)