The Wild Insight
Venus Camera
...expanding our knowledge
| ....The development of
miniature dataloggers to record what marine mammals do underwater
has given us information on how deep the animal is diving, how fast
it is going, the light levels and temperatures underwater, and even
the sounds it hears. However we still have little idea of why it is
doing it.
....Sometimes animals dive straight down and then come straight up again. At other times they dive straight down and then stay at one depth for several minutes before returning to the surface to breathe. Is the first one a quick but unsuccessful look to see what's there, whereas in the second the animal spends time feeding? ....By taking photographs of what the animal is exposed to while it is underwater we are able to answer some of these questions. ....Wild Insight developed a digital video camera modified to withstand the high pressures that these animals are exposed to at depth (pressures up to a hundred times what we feel at the surface). |
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....The camera controls respond to the measurement of depth, for example it can switch on the video when the animal goes deeper than 10 metres. This means it can take pictures during selected parts of dives. There is red-light flash on the camera (red is on the edge of what seals can see and so will disturb them less than a bright white flash). ....The pictures above were taken by the camera when it was put on Antarctic fur seal mothers at South Georgia. These mothers stay ashore to feed their pup for two days and then go out to sea to feed themselves for five or six days before returning to feed their pup again, repeating this for three or four months. A camera was attached to the fur of each female for one of these trips and then taken off when she returned a week later. Almost all of the pictures showed krill and several showed other seals. ....The fact that seals eat krill is not new, however, this technology gives a minute-by-minute loook at what an animal is doing and what it is exposed to, giving information about the decision-making process of the seal, investigating questions such as whether the depth and thickness of a krill swarm affects if it is worthwhile for a seal to bother diving to feed on it. |
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....The pictures are useful for interpreting the behaviour of the seal and also in studying the krill themselves. Krill are not easy to study at sea, but are at the crux of the Antarctic marine ecosystem. ....Observations of krill are generally made by collecting them in nets, monitoring them with acoustic echosounders, or occasionally by observations from scuba divers. ....Fur seals are presumably much better at finding dense patches of krill than we are, and the observations they record on these cameras (in terms of school density, individual krill orientation within the swarm, the depths at which they are found and how these change with time of day) will provide an added dimension to the study of krill in the Antarctic. ....Please note, the images shown have had the quality reduced for fast loading. Click here if you would like to study the images taken by the Venus Underwater Camera more closely. |