Tuesday, 5 October 2010

On things squatty and snotty

Now, where was I? Oh yes, squat lobsters.  I mentioned in my last post that this one was about quarter of an inch long in the body. (Sorry about dodgy pictures - I have lost my trusty Lumix and had to borrow my daughter's camera - which struggles more with close-ups shots).

The other notable thing about it is that it resembles none of those to be seen in any of my seashore field guides nor pictures to be readily found on the web.  Is this some exciting new Northumbrian rarity then?  Cue hilarious seashore pun.  Hold fast!  Before getting carried away maybe there is a clue in its size.  Fully grown squat lobsters are up to 4 inches long in the body depending on the species so this, at about quarter of an inch, is very early stage youngster.  Being a decapod crustacean, the squat lobster's lifecyle goes from egg and sperm to a larval form that floats about in the plankton before moulting into something recognisably squattish.  I gather that the adult colouring and form doesn't immediately appear. Trouble is, that's all the books tend to show you.

If you ignore the colour or lack of it and the yellow socks but study instead the detail of the structures between the goggly eyes, this begins to look like the spiny squat lobster Gallathea spigosa. That's my story and I'm sticking to it.  It is a bonny thing when adult.  This close up is terrific.

And a quick 'did-you-know'. Squat lobsters are more closely related to hermit crabs than lobsters. (How have you got through your life without that fact to hand?)

Its strange how you get no clue about what's under a rock from how it looks on top.  Some turn up nothing yet this one was alive with stuff.  In addition to the squat lobster, there is the breadcrumb sponge it's sitting on, a colony of bryozoans along the edge of the sponge; the spiral tube worm Spirorbis and a few random snotty looking things that are probably sea quirts.

Meanwhile, just along the shore - more strange snotty blobs under a rock
The string of eggs give the game away. Not anemones but sea hares (Aplysia punctata ) - very difficult to photograph under water in a howling gale with a dodgy camera but you can just about make out the curvy flappy structures along their backs.  They are molluscs but their shell is reduced to a very small remnant hidden under those flaps. It is also fair to say that they have very peculiar sexual habits - a sort of interesting variation on the conga.  Each is both male and female, and although there were only two joined up here, they breed in long chains of linked individuals -each fertilised by the one behind while it in turn fertilises the one in front.

The size difference was marked. Nothing in the books about this - though they did tell me that they come ashore to breed in the Spring. Yeah, that'll be right.  There is a crying need for a really authorative and detailed seashore fieldguide I must say.

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