Tuesday, 27 June 2017

The Ultimate Jigsaw Puzzle

We'll make our way up from the beach via the steps by the Porto Belissario hotel and then take a stroll up a track that will take us to the north east corner of the village.  

Now you may think that I'm puffed already, half way up the stairs but honestly, I've only stopped to admire this dragonfly. As you may already know, dragonflies and damselflies form a common group called the Odonata and you can tell them apart by the way they hold their wings at rest. Folded above the body: damselfly. Held out away from the body: dragonfly. There are 19 species of dragonfly on Crete in three  families and this is one of the Skimmers from the largest family, the Libelluidae. Nature is the ultimate jigsaw puzzle and being able to recognise a dragonfly and the family it belongs to is very much a first step; like the initial sorting of the pieces. 

The next part of the puzzle is fitting a few pieces together and if we take a look at these Globe Thistles across the road here we can do just that. As you can see they are being pollinated by a Buff-tailed Bumblebee and two different types of beetle. Incidentally the black and yellow beetle is a Chlorophorus varius which hasn't been recorded on Crete before as far as I am aware. It is the inter-relationships between species that start to show us glimpses of the big picture. 

If we trundle on up this hill a bit we can see the same thing happening on this Thyme, being pollinated by a Mammoth Wasp and two species of butterfly. Which links very pathetically into time being the fourth dimension of this puzzle. The insects we are seeing are all adults. In their juvenile states they may interact with a whole different catalogue of plants and not by beneficially pollinating them but by feeding upon them. Every gardener knows the damage that the caterpillar of the Small White can do to his brassicas and peach growers may well have reason to dislike the larvae of  Chlorophorus varius. 

So far we have been fitting the pieces together very simply; an insect interacts with a plant for food which may either harm or benefit the plant. Here beside the track we have some Lassius niger ants visiting some Fennel, a plant in which they have no particular interest per se. The sap of the fennel is of interest to those Black Bean aphids however and as they gorge on it they excrete the ant attractant sugar melezitose. Conventional wisdom has it that the aphids attract the ants for defence. However a recent paper has shown that this strategy may come at a cost [1]. So our jigsaw puzzle not only changes with time but it is a puzzle of many layers. 

Here we are at the top of the hill and by fitting all the pieces together we can see the panorama on the box. Apart from that cactus being pollinated by our Buff-tailed Bumblebee which shouldn't be in the picture at all. It is a garden plant that is spreading into the wild and in all likelihood pushing out native plants. This may have a knock on effect for the insects that depend on those plants and the birds, mammals and reptiles that rely on those insects as a food source. Nature really is the ultimate jigsaw puzzle; not only is it incredibly complex with over a million pieces, it is multi layered and ever changing. No wonder that it's so addictive. 

The Extra Bit 


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Tuesday, 20 June 2017

Snorkeling The Sea Caves of Ferma

As we have our costumes on I thought we'd continue our journey by swimming back across the bay to those caves over there and I'll fill you in a bit more about the island. When we were looking at fossils a couple of weeks back I mentioned that Ferma was raised from the sea bed by a huge tectonic upheaval about twenty odd million years ago. This is true as far as it goes but Ferma wasn't where it is now. Along with the rest of Crete it formed part of The Aegean landmass and was locked in with Europe and Asia and you could swim from here to the Indian Ocean without the need for the Suez Canal. Another bit of tectonic movement fifteen million years ago nipped off the top end of this large ocean (known as The Tethys Ocean) and the Mediterranean Sea was formed. It wasn't until eight million years ago that Crete began to separate from the Aegean landmass. The final land bridges to the Peloponnese broke about five million years ago and Crete became an archipelago of low islands. The Mediterranean went up and down for reasons of its own and Crete finally settled down to become the island we know today about two million years ago. [1] Which is how the bit of land that was to become Ferma can have 20 million year old fossils even though it has only been there for 2 million years. Makes your head spin doesn't it – or is that just talking and swimming at the same time?

Anyhow, we've reached the caves now and we have a few small fish darting about among the Peacock's Tails. There aren't so many Mermaid's Wine Glasses over this side of the bay I notice. But back to the fish; that little white one with the two black bands is a Two-banded Sea Bream, one of ten species of bream that abound along this coast. With the exception of the Dreamfish that we met in Gully Cove they are all good to eat and form a part of our own food web. It looks as though the cave goes all the way through to the other side so let's climb out of the water and continue on foot.

Have you noticed that all the rocks around the water line appear to have been daubed with Burgundy? That is Red Coralline Algae. It is easy to overlook but it's an important food source for Chitons, Limpets and Sea Urchins. Hello, it looks as if something has made a nest up in this corner. I say nest but that loose bundle of twigs can hardly be dignified with the term. Most birds tend to be a bit more creative than this and I rather suspect that this is the handiwork of a feral pigeon although it does seem a bit close to the water line. Anyone else have any ideas? The cave does indeed seem to go through to the other side but I'm not going to risk getting wedged in that narrow defile. It's also getting rather chilly in here so let's go back out to the rocks and warm ourselves up a bit.

Just at the entrance to the cave here I see that we have some limpets clinging to the wall. These are rather pretty examples, of the Cellana genus I think. We use the simile “clinging like a limpet” for someone who can't be moved - as in “He clung like a limpet to the idea that the Earth was flat.” But their immovability isn't their greatest claim to fame. We often think of spider silk as being one of the strongest materials in nature as it is as strong as high-grade alloy steel. Limpets however have something even stronger: iron teeth. More accurately their teeth are composed of an iron based mineral called goethite and they are five times stronger than spider silk, the strongest teeth of any animal on Earth.

Now, as we stretch out and luxuriate in the warmth of the sun, you can occupy your minds with three little puzzles:

  1. 1. Exactly what is this rock that we're relaxing upon (it's softer than ordinary limestone)?
  2. 2. Why is there a line of very black, rounded pebbles embedded in it?
  3. 3. What are those strange little brown tubes protruding from it?

I have some theories of my own but I'd appreciate your thoughts. Incidentally if there are any geologists or palaeontologists coming over to Crete on holiday this year and would like to spend a morning pottering about with me then please feel free to get in touch.

The Extra Bit

Seventeen days after beginning to pupate Jeremy has emerged as a fully-fledged Vine Hawk Moth – although by the looks of the antennae I think we'll have to rename him Jemima. And isn't she a beautiful insect?

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Saturday, 17 June 2017

Steve's Nature Quiz #12

How many Spotted Sea Hares can you see in this picture?

Sea Hares are a type of Sea Slug and are molluscs like the slugs and snails in your garden. They are called Sea Hares because of their large, hare-like 'ears'. They are not ears at all in fact but act more like noses. When Sea Hares want to make more Sea Hares they form mating chains and advertise the fact by sending out pheromones which other sea hares pick up through these chemosensory organs called rhinopores. As things can be a bit confusing in a mating chain sometimes the best way to determine the number of Sea hares in a chain is to count the rhinopores and divide by two!

I think that I can see ten rhinopores in this picture which makes five Sea Hares. Maybe you can see more?

Taken from this week's #CreteNature Blog:  Triton's Trumpet and Mermaids' Wine Glasses

Tuesday, 13 June 2017

Triton's Trumpet and Mermaids' Wine Glasses

Here we are at Rodinesque Point, a lovely set of rock pools that never fail to  throw up some curious creatures. Before we plunge in though let's have a look at some of the algae that are growing on the rocks. The larger ones are called Peacock's Tails which you may remember we met in the Blue Lagoon; the ones used in anti-wrinkle cream. The ones that look a bit like satellite dishes on stalks are Mermaid's Wine Glasses and both are considered a delicacy by the pretty little sea slug, Elysia timidawhich lives around here so keep your eyes peeled. Incidentally you won't find Rodinesque Point on any map, it's a name I've given the area because of that weird rock formation on the headland which looks as though it has been sculpted by Rodin. 

This looks like a nice place to slither in. Just a note on underwater photography in shallow, rocky waters; if you're using a small camera like this Nikon Coolpix hold the lens in the palm of your hand to protect it. Note two; when getting into the water don't flop on a crab – they don't like it and they have a pair of pincers to prove the point. The one that you just missed down there is a Marbled Crab, probably out looking for a spot of lunch. An omnivorous little fellow eating mussels and limpets and a similar amount of algae but not above snacking on other marbled crabs. On the other hand he has to look out for the occasional marauding gull swooping in from above, the Musky Octopus coming up from below and other marbled crabs of course. 

We'll slide ourselves into the water and see who else is at home. We seem to have disturbed a Goby that has taken off like a rocket. They like to settle, well camouflaged, in the coarse sand and wait for lunch to come to them. They are particularly partial to those little amphipods that we saw last week so I'm told. But what have we here under this rock looking like a miniature orange dolphin? This is a Sea Squirt and they feed in an entirely different way. They suck water in at one end, filter the plankton out through internal gills and then expel it through the other end. It must be an exhausting job because they process their own body volume of water once a second which by anybody's reckoning is knocking on a bit. 

This next pool is a bit deeper so let's see what we can find in here. Now this has to be our find of the day so far, how's that for a mollusc? It's bigger than my hand. Time for a bit of Greek mythology. The Greek god of the sea is Poseidon and he is married to the Greek goddess of the sea, Amphitrite. They have a son called Triton who acts as his dad's herald. Both Poseidon and Triton carry tridents but Triton has a special implement for calming or rousing the waves (as well as general heralding) in the form of a large twisted conch shell. This is it: Triton's Trumpet – give it a blow, he won't mind. Oh sorry, I hadn't noticed that it was still occupied. It also works better out of the water, come to think of it. 

If we squeeze through this narrow channel we'll find some less protected waters bordering on the open sea. The best way to explore these is to get out and sit on a rock and gently probe through the algae with your fingers and toes. Now that even beats Triton's Trumpet; a trio of Spotted Sea Hares. Note the 'ears' which give them their name. They are a type of sea slug and as such they are hermaphrodite, being both male and female at the same time. When it comes to mating time they form chains like this and they advertise the orgy by releasing a cocktail of pheromones into the water. Scientists in Galveston, Texas (who obviously have a waggish sense of humour) have identified four of these pheromones and named them SeductinEnticinAttractin and Temptin [1]. I take my snorkel off to them. 

The Extra Bit 

Jeremy the Vine Hawk Moth is still pupating so I can think of no better way to round off than just watching the sea hares making more sea hares.  

Share your nature thoughts, photos and comments on Naturalists(the facebook page that accompanies this blog) 
See detailed pictures onFlickr 
Read more about the flora and flora of the island in The Nature of Crete(Flipboard Magazine) 
Explore the region with the #CreteNature interactiveHiking and Nature Map 

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