Taking It Easy

What a lovely day for wandering along the beach and taking it easy after our exertions down the valley. I see that we have another of those Bee flies that we were discussing a few weeks back (see The Sweet Smell of Rain) investigating the sand. Quite an absorbing pastime and there are hobbyists who collect sand, studying its composition from places around the world. The bit that the bee fly is studying for instance contains dark grains, pure white grains and at least fifty shades of grey in between. The colours are determined by the mineral content and the shape depends upon whether it has been washed down from the hills or transported by wind and waves. Ours is angular suggesting that it has come down the valley like us and the colouration is typical of quartz and chert with that odd orange bit by his abdomen probably coming from one of the iron bearing rocks that we observed in How To Get Blood Out Of A Stone.

Let's walk along the back of the beach and see what else we can find. Those bunches of strap like leaves will throw up fragrant blooms of white Sea Daffodils in the summer but we have one common beach plant blossoming here and now and that's Sea Rocket. The seed pods have a very high concentration of erucic acid which is an omega 9 fatty acid and has a bit of a story behind it. You may be familiar with great yellow fields of rape, from which we get rapeseed oil. Rape and sea rocket are closely related and both contain high levels of this acid. We cultivate rapeseed oil for biofuel, animal feed and edible oil but the high levels of erucic acid became a cause of concern after laboratory tests in the 1970s showed that if you stuffed rats full of the stuff then it had a toxic effect on the heart. To be honest, if you pig out exclusively on anything it will probably do you harm – even water can poison you in high enough doses. Enter two bright sparks from the University of Manitoba in Canada who bred rapeseed low in erucic acid and called it Canola oil. Nowadays we just genetically modify the plant of course and canola is widely marketed as the healthy cooking oil. I'll let you make your own mind up on that one.

Here's a pretty little lady, she's a Long tailed Blue. Not as showy as the male who has a lot more blue on his upper wings but it pays not to be too conspicuous when you're sitting there egg laying. This maybe what she has in mind now. Her caterpillars feed on a wide range of leguminous plants in the Fabaceae family such as this Cretan Ebony which is just coming into flower. Shall we take a wander down to the sea and clamber along those interesting looking rocks over there?

That seems like a nice place to stop and watch the marine world go by. Not much in the way of fish today... the odd shore crab scuttling about... but there's some seaweed down there which may be harbouring some microscopic life. Let's have a look. Ah, our old friends the diatoms, the very basis of the food web. These are marine diatoms and different to those that we found under the dripping stalactite in A Recipe For Life.

Those wedge shaped ones often cluster together, narrow ends facing inwards, so that they make a complete circle like a flower head. I expect that we disturbed them when we rudely hauled them out of the sea and plonked them on a microscope slide. I think we'll rinse the slide and put them back. You know, it's almost warm enough to join them in there. Maybe in a couple of weeks. When the sea's had a chance to warm up a bit.

The Extra Bit

If you'd like to become an arenophile and collect sand as a hobby there's a society just for you: http://sandcollectors.org/become-a-collector/

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LINKS:

Share your nature thoughts, photos and comments on Naturalists (the facebook page that accompanies this blog)

See detailed pictures on Flickr

Read more about the flora and flora of the island in 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)

To St. John’s Ford

Algerian Iris, Iris unguicularis

Here we are below the Milonas waterfall and the cataract is still tumbling down through the rocks sounding like a symphony of swirling streams. A veritable jungle of giant cane and oleander surround us and up among the rocks small flowers like this Algerian Iris are taking advantage of every crack and crevice that holds a modicum of soil.  Not only is it a ridiculously pretty little flower but its rhizomes - the underground stems - contain some useful compounds (Kaempferol and 8-Methoxyeriodictyol if you're into phytochemistry), both of which are important in the fight against diabetes and a wide range of cancers^[1].

 

Tropinota beetle and Spilostethus Seed Bugs

It looks as though machetes will be needed to get through this next bit so I think we’ll take a detour up over the bank. With the temperatures now in the upper twenties Celsius and wall-to-wall sunshine the insects are anticipating next week’s spring equinox. The hairy Tropinota Beetles are all over the place and this one is gorging himself on a Cretan Cistus. Some insects, like the bees, flit from flower to flower but he’ll be there for an hour or more availing himself of every last bit of nourishment. Meanwhile the seed bugs are busy making more seed bugs. Unlike the Tiger Beetles who go for the direct mounting technique (see last week) Seed Bugs prefer the back-to-back method of mating. Not particularly romantic but equally effective.

Caddisfly larva, Trichoptera sp.

I can see a light at the end of the tunnel; if we just thrust our way through this bush… ah, we’re back to the stream. Let’s sit and peer into it for a bit and get our breath back. Pass me the net will you, I think there’s something going on down by that rock. Now why do you think that this little nymph is poking his head into that pile of sand? He’s not doing it voluntarily. That pile of sand is hiding a Caddisfly larva. There’s another one down there look. They spin a cocoon of sticky silk around themselves and cunningly cover it with surrounding materials; sand and grit in this case, then lay in wait and ambush unsuspecting prey. Our poor nymph is being eaten head first.

Diatoms

If you look at some of these rocks they’re covered with rather uninteresting looking brown slime. This is the next stage of the biofilm that we saw developing in A Recipe For Life. If you take the sampling kit – yes, that’s it: a screw top container and an old toothbrush. Just half fill the container with water, scrape the rock with the toothbrush and stir item 1 with item 2 – I’ll set up the field microscope and we’ll see what’s lurking within. Look at that, no less than nine species of diatoms; those minute life forms at the base of the food web. Fascinating aren’t they?

Spawn of the Green Toad, Bufotes viridis

Signs of civilisation, a vehicle track. If we were to follow it round to the left we’d find a waymarked path to the waterfall (but it wouldn’t have been as much fun as hacking through the undergrowth). To the right it goes down to Ferma Bay one way and up to Agios Ioannis the other. As I’ve said previously Agios Ioannis translates as St. John so I’ve always called this place St. John’s Ford but you won’t find it marked as such on any map. I see that the Green Toads have been busy. That clump of what looks like spotted snakes coiled around those reeds is toadspawn and the black dots are emerging tadpoles, there are a few swimming around look. You can tell that it’s toadspawn and not frogspawn because toads lay their spawn in long strings whereas frogs lay theirs in a jelly-like mass. Worldwide, amphibians are suffering deaths to the point of extinction in some species from ranaviruses^[2] but thankfully I’ve seen no signs of it locally. However, we’ll keep an eye on them on our travels.

 Talking of which, I think we’ll call that it for today and explore downstream next week. Spring will have well and truly sprung by then so it will be ‘eyes everywhere’ to catch all that’s going on.

The Extra Bit

Those diatoms we were looking at under the microscope are interesting enough when they’re still but when you watch them going about their daily business they are absolutely mesmerising. Here’s a short video for you:  https://youtu.be/DWctIwT3dFI 

^[1] http://www.sciencedirect.com/science/article/pii/S0024320512007175

^[2] http://www.savethefrogs.com/threats/chytrid/ranavirus/

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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)

The Dew Ponds of Katharo

We’re taking a break from our trek up the Eden valley this week as I want to take you up to the Katharo Plateau in the Dhikti mountains. Yes, I know we’ve been there before (Cathartic Katharo) but I need your help to examine some summer ponds.

Cirl Bunting, Emberiza cirlus at one of the dew ponds

Here we are, all dressed up in muted colours for the occasion, and our first job is to lie very quietly in the mud and see what’s happening. These ponds retain water all through the long, dry summer and I believe that they work on the same principle as the Hampshire dew ponds that the eighteenth century English naturalist Gilbert White described in his book, The Natural History and Antiquities of Selborne. That is “more than double the quantity of dew falls on a surface of water than there does on an equal surface of [moist] earth”. The clayey soil in which we’re lying prevents the water from seeping through the limestone rocks. As you can see it’s a great place for dragonflies and we have birds popping in for a drink. There’s a Cirl Bunting, look. Many buntings have declined in North West Europe due to a lack of weed seeds and insects but they’re obviously alive and well here on Katharo where traditional farming practices are still employed and herbicides and pesticides are not.

Water Strider, Damselfly larva, Water Scavenger Beetle

Let’s take a look under the water and see what’s lurking there. What do you mean you didn’t bring your bog snorkelling gear? Ok, you sit and watch the Water Striders skimming about the surface and I’ll go down and interview the wildlife. A small Water Scavenger Beetle, though that is a bit of a misnomer as they can be just as predatory as the Predacious Water Beetles. You can tell them apart by the way they swim: these move their hind legs alternately but the Predacious Water Beetles kick theirs out together – sort of doggy paddle versus the breast stroke. We also have a Damselfly larva. These larvae are also known as naiads or nymphs after the female spirits that dwelt in wells and streams in Greek mythology. You can tell that it’s a damselfly and not a dragonfly by those three tail filaments containing the gills through which they breathe. Dragonflies don’t have these and breathe through their rectums (which is not something you should try at home).

Apart from each other I wonder what else these little creatures are eating? For the omnivores and vegetarians down there we have plenty of this stuff. It’s called Chara and though it looks very much like a plant, it isn’t. It’s a green alga and, as such, is more closely related to green seaweed than flowers. The little red buds that you can see contain reproductive spores and, as you can tell by the amount of Chara in the pond, they are remarkably efficient. This is just the top level of the ecosystem that we can see with the naked eye; there’s far more going on that we can’t see so grab a pipette out of my bag there and we’ll put a drop of water under the microscope.

Desmids and Diatoms

Ah now, these top two, Closterium and Euastrum are desmids which are green algae, the same as the Chara but they are unicellular. The Euastrum looks as if it has two cells but they are in fact symmetrical compartments of the same cell separated by a narrow bridge. The bottom two, Epithemia and Rhopalodia are diatoms which are more closely related to the red algae. Forensic scientists love these things because if they find them in a murder victim it shows that they were drowned rather than killed and then dumped in the water. If they can correlate the species mix in the corpse with the species mix in a certain pond for instance they can even tell where the person was drowned. Gruesome perhaps but just one of the obscure ways that a knowledge of nature impacts upon our lives.

The Naturalists' Taverna, Katharo

What a fascinating little pond; water, water everywhere but not a drop to drink. I think that we’d better rectify that and a visit to Yanni’s taverna is a must when visiting Katharo. Yanni is a naturalist himself and you can spend a pleasant hour or two reading the walls of his taverna over a convivial libation. There are pictures and descriptions of birds; books and posters of flowers (provided by our friend Steve Lenton at Cretan Flora) and a section on the fossil mammals of Crete, some of which Yanni himself discovered. It’s surely the best naturalists’ taverna on Crete. Who’s round is it?

News Update

Remember that little diatom called Rhopalodia that we found? It turned out to be Rhopalodia gibba, a species never before recorded on Crete. As such it has now been documented on the world wide Algae Base. Better not drown anybody in that pond then.

I see that my email address is at the bottom so feel to drop me a line, contact me on twitter @cretenaturalist

or via

Naturalists (the facebook page that accompanies this blog)

See you next week.

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LINKS:

Cretan Flora

Flowers of Crete;

BIRDS OF CRETE

Crete Birding

Greek Butterflies and Moths

Aquaworld Aquarium

Visit Greece (National Government Tourist Office)