Depth Limits - Why are animals different?

[sandym]

My question is...How can dolphins and whales dive to incredible depths while scuba divers are restricted to the near surface waters? Does anybody know?

 

[gfisher4792]

Short answer: their physiology is different then ours (you can find discussion on this on the board, on the web, and even in one of the recent issues of Dive Training), and they're holding their breath while underwater, instead of breathing compressed air, thereby avoiding the bends factor (more or less).

 

[chrisch]

If you can hold your breath for an hour and sleep underwater you too can dive to "incredible" depths...

 

[H2Andy]

yeah... the limiting factor on humans descending deep is not pressure. our bodies can handle A LOT of water pressure.

the limiting factor is the fact that we can't hold our breath too long, so we have to take gas down with us. gas does funny things to humans at depth (i.e. under pressure).

 

[glbirch]

My question is...How can dolphins and whales dive to incredible depths while scuba divers are restricted to the near surface waters? Does anybody know?

Don't forget the Elephant Seal, an amazing diver cabable of two HOUR submersions.

Let's see... whales and seals have a larger blood volume and greater oxygen-carrying capacity than we do. Sperm whales have far higher levels of myoglobin in their muscles, which is an oxygen-binding molecule similar to haemoglobin. The muscles of diving mammals also have greater amounts of creatine phosphate, which is used to create energy. The muscles of some diving mammals such as the Weddell Seal, once they have used up stored oxygen, change over to anaerobic metabolism, generating energy without requiring oxygen. This causes a build up of lactic acid in the muscle which must eventually be gotten rid of by combining with oxygen after surfacing, but certainly increases available bottom time. The diving reflex also factors in, as heart rate and metabolic levels drop sharply upon submersion. Blood flow to the extremities also decreases as vessals constrict, conserving oxygenated blood for the vital organs in the body core.

Don't forget as well that these are all breath-hold divers and thus do not have to worry about factors such as N2 buildup in their tissues or O2 toxicity which are two major limiting factors for scuba divers.

 

[H2Andy]

good details there... here's a great article on diving deep:

http://eee.uci.edu/courses/bio112/diving.htm

from that article:

Among these polar creatures, the quintessential avian diver is the emperor penguin, which can attain depths greater than 500 meters while staying submerged for about 12 minutes. In shallower dives, an emperor penguin may stay submerged even longer, over 20 minutes. Among mammals, the supreme diver is the sperm whale, which can dive down over 2,000 meters, and the northern elephant seal, which can descend to depths below 1,500 meters. The Weddell seal, about which most is known and which we study, is somewhat less dramatic in its dives. Still, it can descend to 700 meters, and at times it may remain submerged for 82 minutes, which makes it far superior to people.

 

[archman]

The Weddell seal, about which most is known and which we study, is somewhat less dramatic in its dives. Still, it can descend to 700 meters, and at times it may remain submerged for 82 minutes, which makes it far superior to people.

This critter is considered by most marine mammal dorks to be the king of deep divers. The reported depth limits are false, as that represents the seafloor around Antarctica, and not their dive limit. Weddell seals hit bottom pretty quick. Nobody knows how deep they could ACTUALLY go.

 

[H2Andy]

i dont know... my Wedell seal just hangs out eating fish and barking at the cats...

 

[SeaJay]

Heh.

 

[mbuff]

I think the deepest divers are the elephant seals... 5000 ft. is not uncommon and I believe they've been tagged deeper than that.