We were enticed into the calm, sheltered blue waters of Lady Bay (Mull of Galloway) on Saturday (29th September 2009), only to find that conditions were pretty much un-diveable, with lots of suspended silt giving a visibility of about 10cm! You could see which way was up, and that was about it…

Having got wet, however, I decided to try and get some samples for microscopy, and got a rather nice sample of sea mat on a laminarian. Sea mat is an ectoproct, a colonial animal that is commonly found forming white reflective sheets on kelp fronds, look closer and you’ll see that the sheet is formed of lots of tiny cell-like structures, but that is about as much information as you’ll get with the naked eye.

Under the microscope, however, we can see that each cell is an individual animal – the colony being formed by numerous clones living tightly packed together. When feeding, each animal extends a cone of tentacles, which are quickly retracted if it is disturbed.

Above right: Two micrographs of Mambranipora membranacea (L): Top showing extended feeding arms of the lophophore. Bottom, showing the growing edge of the animal, on Laminaria sp.

Barry