Milly: Ugly Fish pt 2
Milly: Ugly Fish pt 3
Milly: Ugly Fish pt 4
Milly: Ugly Fish pt 5
Milly: Ugly Fish pt 6
Milly: Ugly Fish pt 7
Coming back to my post about pressure (pt 6), how are deep sea animals adapted to survive at depth?
As there are all sorts of animals currently inhabiting the deep, I'll concentrate on fish. Fish are the best anyway. Slightly biased.
Well the problem is, fish don't just have to cope with the crushing pressure (up to 800x greater than at the surface) but the deep is also very dark (beyond 1000m there is negligible surface light) and cold (2°C) making things such as moving around, finding food and reproducing much more challenging. Let's have a look at a few fish and see how they do it. Enter handsome fellow number one, the anglerfish.
|Whipnose anglerfish, about the size of a football. |
Note the long lure with the tiny esca on the end, capable of bioluminescing.
Image: Dianne Bray
|A selection of anglers. |
Image: Dr Theodore W. Pietsch and Christopher P. Kenaley
There are 11 families of deep sea anglerfish, some only containing one species, such as the lonely prickly seadevil, Centrophryne spinulosa (Centrophrynidae family) others have many more such as the footballfish, Himantolophidae with 19 species. They are a surprisingly diverse group of ugly fish. As you can see from the pictures above, these animals don't look particularly athletic. If you were to design an animal for a race underwater I doubt 'round' would be the shape you would go for. Nevertheless, these are very successful bathypelagic (1000 - 4000m) animals, but why? Anglerfish are sit and wait predators and with the aid of their bioluminescent lure, can draw in prey such as fish and cephalopods (squid etc) within gobbling distance. The bioluminescent light, which can be controlled producing flashes or sustained glowing is the product of many bioluminescent bacteria that colonise the lure (or esca). They don't even need to feed particularly often since they expend such little energy, evident when you touch one of these animals. Their bodies are both flabby and bony (an attractive combination) suggesting they do very little excercise. Lazy little anglerfish. Not only are they lazy but seriously greedy. An expandable stomach allows anglerfish to munch down prey twice their size. A human man could fulfil his daily allowance of calories with 850g of meat, less than the weight of a mature trout! Seriously rubbish in comparison.
|Sea devil (Melanocetus niger), about the size of a |
golf ball, look at that mouth! Image: Milly Sharkey
|A female angler with the tiny parasitic male attached. |
Image: Dr Theodore W. Pietsch. University of Washington
More later, I need to locate pre-trawl pudding.