Poring over Porifera

The minute I turned to the page in the field guide and read, 'for all their simplicity these are the most difficult to describe carefully and scientifically' I knew I should have picked crabs.

Along with a hundred or so other volunteers, I am taking part in the Big Sea Survey on the NE coast of England. This brilliant scheme aims to plug a huge gap in knowledge of the status of intertidal life by harnessing volunteer power, trained and supported by Dr Heather Sugden and colleagues at Newcastle University's Dove Marine Laboratory, to carry out surveys using reproduceable scientific methods.

So it is that I am looking at sponges (someone's got to do it) and headed down to the low tide rocks at Beadnell in Northumberland.  The kelp zone is a fabulous, alien environment, perfect for honing your swearing skills. If you don't believe me, you try walking on rocks covered in Laminaria digitata and see what comes out of your mouth. 

It doesn't look much on the surface....

... but part the slimey fronds for the full technicolour experience.

Things get interesting when you try to identify the species of sponges here.  The guidebooks assist with  phrases like 'white-orange-yellow-green-brown' ; 'form may be very variable' ;  'surface furrowed or smooth' and other really helpful things.  The commonest by far here is the breadcrumb sponge Halichondria panicea. Although the colour varies the form is predictable with these prominent volcano features:-

Sponges are simple little animals packed together in colonies.  They take in water through the general structure and then eject it via the craters (oscula), filtering out goodies in the process.  Some very interesting things feed on them too - sea slugs for example.  Right next to this patch was a beautiful, delicate swirl of eggs produced ( I think) by one particular nudibranch - the Sea Lemon.  There must be millions of tiny eggs in this mass - which was about 4cm across with the curtains standing a centimetre in depth off the rock.

I'm a convert. Sponges are cool. And at least they don't bite your fingers.