Steve's Nature Blog: 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. Exactly what is this rock that we're relaxing upon (it's softer than ordinary limestone)?
2. Why is there a line of very black, rounded pebbles embedded in it?
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?

[1] http://www.cretanbeaches.com/en/facts/geology-of-crete

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