Hi,

We were wondering how long seals can hold their breath for underwater? and whether it varies dramatically between different breeds of seals?

Thanks.

G’Day Guys:

Seals have a number of adaptations that allow them to ‘hold their breath’ for extended periods underwater. For example, a high proportion of oxygen is stored in their blood (and not the lungs) - their blood has more haemoglobin than ours. They channel blood to critical organs such as the flippers, heart and brain during a dive. Their muscles also contain large amounts of myoglobin, which is related to haemoglobin, and this helps them to conserve oxygen during deep dives - they tolerate the large build-up of carbon dioxide in their blood better than us. Compared to humans, seals also are better at handling the increase in muscle lactic acid.

There is data on how long seals can stay under water, even some published studies in the laboratory or field. For example, juvenile northern elephant seals had a mean, free dive time of only approx. 6 min in a laboratory setting (see: http://www.ncbi.nlm.nih.gov/pubmed/9472819)  but this would likely increase if the animal was feeding and/or in the wild. Dive times of over 100 mins have been reported for adult elephant seals, which are among the largest seals (e.g., up to 6,000lbs). Other species of smaller seals have reported dive times from 25 mins (Harbour seal: approx. 280lbs; see: http://marinebio.org/species.asp?id=158) to an hour or more (Gray seal: approx. 900lbs and the Antarctic Weddell seal: approx. 800-1000lbs; see: http://marinebio.org/species.asp?id=331). 

So there does seem to be a slight trend for dive times to increase with size - however, for Leopard seals (up to 1000lbs), one of the top predators of the Antarctic seas, a value of only 15mins has been reported (see - http://marinebio.org/species.asp?id=160). The Leopard seal does not dive to the depths of other seals because they are shallow water hunters. So that is quite a dramatic difference based on feeding behaviour. However, how long could a Leopard seal theoretically stay under water? Or any other seal species? I don’t know whether there is an answer to these questions, or the inclination or resources for marine biologists to compare a number of different species in a controlled, scientific study!

Last edited by Steve Lolait (1st Jul 2011 21:47:29)