What a change a few degrees make...
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...
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.
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.
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.
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.
Can't help feeling bad for the urchin though... they are pretty cool in their own right.
Thursday 21 July 2011
Sunday 5 June 2011
Jelly
While vacationing off the coast of Wales, I've been seeing a lot of jellyfish. In addition to the common moon jellyfish, there have also been large numbers of Blue Lion's Mane (Cyanea lamarckii), Barrel jellyfish (Rhizostoma octopus) and By-the-wind Sailors (Velella velella).
Cyanea lamarckii - Abersoch, Wales
Moon jellyfish and Blue Lion's Mane are not uncommon species, but this is the first time that I have seen By-the-wind Sailors. What surprised me the most is the size - the descriptions say that they grow up to 10 cm, but almost all that I saw were 1cm at best, although there were many of them. Occasionally I would see a larger one, but no longer than 2cm at most.
Velella velella - Harlech, Wales
There were large numbers of Barrel jellyfish close to the shores of Cardigan Bay - I counted almost 20 in three days, all but three of which were washed up on shore. They aren't supposed to be coming this close to the beach, but apparently these mass sightings do happen when the weather is unusually warm. The picture below was taken from the edge of the marina in Barmouth. Hopefully he managed to escape to deeper water before the tide retreated.
Cyanea lamarckii - Abersoch, Wales
Moon jellyfish and Blue Lion's Mane are not uncommon species, but this is the first time that I have seen By-the-wind Sailors. What surprised me the most is the size - the descriptions say that they grow up to 10 cm, but almost all that I saw were 1cm at best, although there were many of them. Occasionally I would see a larger one, but no longer than 2cm at most.
Velella velella - Harlech, Wales
There were large numbers of Barrel jellyfish close to the shores of Cardigan Bay - I counted almost 20 in three days, all but three of which were washed up on shore. They aren't supposed to be coming this close to the beach, but apparently these mass sightings do happen when the weather is unusually warm. The picture below was taken from the edge of the marina in Barmouth. Hopefully he managed to escape to deeper water before the tide retreated.
Sunday 8 May 2011
Its been a while
Diving season is back, no more quarries, actual sea life!
Most divers go for the rocky terrain, and why not? Lots of nooks and crannies for things to hide in, and good attachment surfaces for the more sessile marine dwellers. But this fellow I found in the open sand. This is a little cuttlefish (Sepiola atlantica) which was hiding in the sand until I disturbed it. To give some sense of scale, he is about the length of my thumb.
This is him in action.
Most divers go for the rocky terrain, and why not? Lots of nooks and crannies for things to hide in, and good attachment surfaces for the more sessile marine dwellers. But this fellow I found in the open sand. This is a little cuttlefish (Sepiola atlantica) which was hiding in the sand until I disturbed it. To give some sense of scale, he is about the length of my thumb.
This is him in action.
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