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This week at Mawson: 10 May 2013

Here is a bit of interesting information about the diving specialities of the Weddel seal that I came across while reading one of the books in the library here at Mawson.

  • To reduce buoyancy and therefore save energy, they exhale before descent.
  • They have twice the volume of blood per kilogram of body weight than humans and their blood contains about 1.6 times more haemoglobin than us. The combined result of this is that the seal's blood can store up to 3.5 times the oxygen we can.
  • A Weddel seals dive can last for up to 73 minutes.
  • When they make long dives their heart rate slows and blood is circulated through the heart, brain and lungs only. Blood flow to the muscles and other organs is reduced by 90%.
  • A dive lasting 45 minutes requires a recovery time of around 105 minutes.
  • They often feed on the sea bed at depths of 400 – 600 metres.
  • Seals have a system of blood vessels within the middle ear that fills with blood as they dive deeper to prevent the walls of the middle ear collapsing due to pressure.
  • Unlike humans, they don’t have nasal sinuses.
  • A small amount of air is retained in the lungs and wind pipe so they can produce underwater vocalisations.

All in all not just a slug lazing around all day on the sea ice but a unique animal perfectly adapted to life down here in Antarctica. 

Weddell seal with pup
Weddell with pup
(Photo: Peter Layt)
Weddell head protruding from a hole in the ice
G'day, sup?
(Photo: Peter Layt)
Weddell seal stretching
Ballerina seal
(Photo: Peter Layt)
Weddel stretching on the ice
Yawn, stretch and come to life - workin' 9 to 5!
(Photo: Peter Layt)
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