shark snacks

September 8, 2005 4:35 PM

Why would great whites take only the heads of seals?

When I was living in Northern California I encountered the bodies of headless seals twice. It was generally accepted that great white sharks had taken the heads. That's a reasonable explanation and google'ing around confirms that headless seals are an indicator of shark activity. Why only the heads? Attacking the head makes sense to insure a quick kill but there's a lot of nice juicy fat on the seals bodies. The shark has already expended the energy to kill the seal. Why not come back and finish lunch?

Is the seal density so high that a great white can just keep snacking? Is it that we don't see the kills that are completely consumed? Has anyone done enough observation of great white feeding habits to know the answer?

posted by rdr to science & nature (9 comments total)

Just so you know. I've met someone that on more than one occasion has been a part of a scientific / educational group that cuts the head off of dead sea lions (or maybe it was seals, I cannot remember...) that were laying on the beach. While illegal for "normal" people to go out on the beach and do this, I'd imagine it happens too. Might these headless seals just be the victims of people / scientists looking for a skull? I've never heard of sharks only eating the heads...
posted by pwb503 at 5:50 PM on September 8, 2005

For the creamy nougat center?
(sorry...couldn't resist)
posted by Thorzdad at 6:06 PM on September 8, 2005

I can smell your brains.
posted by johnj at 6:52 PM on September 8, 2005

(sorry. . . me neither)
posted by johnj at 6:53 PM on September 8, 2005

Here is an article that may explain the head taking 'bite and spit' and also why 'balancing an energy budget' causes them to leave the rest "in terms of per unit mass, fat has twice the calorific content of protein, blubber is fairly resistant to digestion and (on a calories liberated per unit time basis) doesn’t represent a particularly rich food type".
posted by tellurian at 9:12 PM on September 8, 2005

brains are much more nutritious than fat. You see the same behaviour in bears taking salmon - if there are enough available, they'll eat only the brain.

Either that or zombie sharks.
posted by polyglot at 10:11 PM on September 8, 2005

Heads, you win; tails, you set loose.
posted by rob511 at 10:32 PM on September 8, 2005

Maybe that is the real reason zombies only eat the brains. It is more efficent.
posted by TwelveTwo at 12:55 AM on September 9, 2005

My cat does the same with mice. He has a plenty of Iams which he seems to enjoy, so perhaps his motives are more shark like.
posted by verisimilitude at 6:40 AM on September 9, 2005