Thursday, 27 October 2011

Color in the depths

No flash required.  An adult and a juvenile Rainbow wrasses by a rocky outcropping at Tabarca Marine Reserve, Spain.  

What a change a few degrees make...

Wednesday, 5 October 2011

Color in the depths

The Spiny Squat Lobster (Galathea strigosa) is one of the more striking denizens of the depths in UK waters. This specimen I photographed at the Farnes was not to keen to pose, but I was able to capture some of the brilliant blue patterning that characterizes this species.

Its interesting to speculate what the purpose is of the bright blue lines, considering that without the benefit of a camera flash, the murk and darkness soaks up much of the color and that these crustaceans are most active at night. The key, I suspect, is that the color blue is one of the last colors to fade out as you go deeper, and would be one of the few still visible at depth (the orange, in contrast, would be indistinguishable from other nearby colors). Some crabs have been shown to make use of coloration patterns to distinguish conspecifics and to evaluate potential rivals, while the lines (appearing as dark streaks on a light background) could help confuse predators by breaking up the body pattern.  Other than some speculative observations on the related Galathea intermedia I haven't come across any studies that try to test this, however.

Monday, 3 October 2011

Wheres Waldo underwater

Can you find the Painted Gobies (Pomatoschistus pictus) in this picture? (Taken at the Farnes, Sept 17, approx 20m depth).

(hint - click on the photograph to enlarge)

Elegant anemones

If you look closely at rock walls or hard substrates while diving on the NE coast of England, you'll probably see these small anemones... they are usually only a centimeter or two wide, and without a torch are easy to miss amidst the dead-mans fingers, urchins, and encrusting sponges. They can be very colorful, but that is a detail easily overlooked in the murk at 20 meters down.

Most of the anemone is actually stuffed into a crack in the rocks giving them a much flatter profile than the Plumose anemones (Metridium senile) that can be found nearby.  The cracks can be quite narrow... compare for example the size of the 'head' and the width of the cracks in the image below.

So what are they?  Well... thats a bit hard to say.  They are almost certainly in the family Sagartiidae, and probably Sagartia ornata, but could also be small Sagartia elegans.  The small size makes me think the former, but this is not an easy group to identify from photographs alone.  Short of returning with a crowbar or a rock hammer to dig them out, the best I can do is appreciate the beautiful effect they have on the underwater surfaces.

Saturday, 1 October 2011

Schools in

The experience of  a school of fish passing through the murky depths can be mesmerizing...  I was lucky to encounter a large school of pollack (or saithe) while diving off the Farnes... usually these fish are found in much smaller groups.

Its hard to tell from the video whether they are saithe or pollack - the difference is in the curvature of the lateral line, not something obvious given the poor visibility.

I feel bad for the urchin

Farnes, Sept 2011.  My dive buddy decided to keep the ballan wrasse's interest by cracking open an urchin, while I got busy with the camera.

Can't help feeling bad for the urchin though... they are pretty cool in their own right.