FAQ
A contribution of The Cephalopod Page
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James, In your studies of deep sea octopus have you tackled the question of whether or not the animals are dependent on the enormous pressures of the deeper waters? The was some talk on CompuServe's Fishnet on whether or not some of the fish that are being collected recently would be affected by the lack of pressure that exists within our aquaria.
Michael |
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| No, pressure is one variable that I have not been able to test for. As you can probably imagine, keeping an animal continuously under pressure is a bit tricky - simple things like feeding and cleaning the tank become logistical nightmares. When I was a graduate student I had an extremely limited budget. At Dalhousie we had a tower tank 30 feet deep - the problem was that it cost $90/day to use it and my deep sea animals grow so slowly I'd probably need it for half a year to get any significant differences in growth. If someone else uses it for a long term project (no one has in the last three years) AND I have hatchling octopuses available I'll try and check this out. Sure, I could test this in the field but there would be to many confounding factors to prove anything (ie the water temp at depth is colder, light, different currents, etc) and I'd have to dive in the frigid Canadian waters and have frequent access to a boat. As it stands now though, I'm not likely to test this. I can say that my near shore octopuses seem to do much better then my deep sea ones. This could be due to a lot of factors, one of them is pressure.
The scallop trawls that catch my octopus's fish at over 75 meters and the fish (at least those that have swim bladders) that come up in these trawls have had it. Octopuses, which do not have swim bladders, are much better off. About 5% of them look like they have had problems with blood vessels bursting - these animals may live but they often do not do well. By the way, I think there are two issues for you to think about here. The first is the effect of pressure - are animals that live deep adapted to the pressure? Do their enzymes work better when the pressure is high? If so, what is the magnitude of this? The second question, which is very important for fish as they have enclosed air spaces, is what is the effect of rapidly changing pressure on an animal - i.e. bringing up a fish from depth. Are there long term effects of using a needle to drain out the air of a fish's swim bladder? How much are internal organs damaged by the expanding swim bladder during ascent? Is a 24 hour decompression better? Dr. James Wood |