It's this type of arguement was first used for flying aircraft. Up until that point you had "lighter" then air crafts such as zepplins and hot air ballons. To make a heavy metal or even wood craft that could fly was deemed impossible. When a plane is not moving it isn't using principlas of physics and more specifically the dread Bernouli's equation to attain flight. Such as objects which "float". By displacing a equal amount of water in volume as you weight you will float. If you displace more water then you weight then you float "higher" or in laymans term you are more buoyant. So for animals the act of swimming is keeping them buoyant by displacing a volume of water equal to their weight. For humans we are generally given a index of .4-.7 meaning that up to 70% of our bodies weight will be displaced. The other 30% will cause us to sink but by threading water to displace more water or by lying on our backs therefore increasing our bodies surface area and causing more displacement we float. That is why life vest aren't so freaking huge like a pontoon on some water craft. The vest only has to account for the 30% of a persons mass. I suppose Hippos have it harder but in any case they can swim.

What I have just said will have inaccuracies in it. I'm not working so Al's working brain is off at the moment.

I think I have a problem with this logic: "if they don't float, by elimination, they sink." It applies to immutable objects (pieces of wood, stones, etc.), but not living creatures. If I straighten out vertically in the water, I sink, whereas if I lay horizontally at the surface, I'll float. And if I swim, continuously propelling myself forward and upward, am I sinking? Am I floating?

In any case, not to belabour this point, but here's the original source. Perhaps it will clarify things:

Adult hippos are not generally buoyant. When in deep water, they usually propel themselves by leaps, pushing off from the bottom. They move at speeds upto 8 km/h in water. Young hippos are buoyant and more often move by swimming, propelling themselves with kicks of their back legs. One hippo calf survived after being pushed out to sea during the tsunami generated by the 2004 Indian Ocean earthquake and was rescued on a nearby island.

Baby hippos are born underwater at a weight between 25 and 45 kg (60−110 pounds) and must swim to the surface in order to take their first breath. The young often rest on their mothers' backs when in water that is too deep for them, and swim underwater in order to suckle.

Adult hippos typically resurface to breathe every 3–5 minutes. The young have to breathe every two to three minutes. The process of surfacing and breathing is automatic, and even a hippo sleeping underwater will rise and breathe without waking. Hippos have been documented staying submerged for up to thirty minutes.

that was my point, though... if they don't float, by elimination, they sink... and then they must be able to breathe under water... sheesh.

well, anyway, i'm off to GP tomorrow... so happy long weekend everyone.

Hippos probably can swim without being buoyant for the same reason that humans aren't generally buoyant, and yet can swim. Also, I believe hippos (like their closest relatives, whales) do not breathe underwater. They resurface.

Paras, if adult hippos are not generally buoyant, how do they swim, and breathe under water?

The first set of pics from the Oilogosphere Classic are on the Flickr:

And, while I'm at it, Rumsfeld Tribute on Craig Ferguson's show:

Office Space as a thriller:

Leo want to do something tonight?

Remember