Expert: Dana Krempels, Ph.D. - 1/3/2011

Question
How many giant squid live in the oceans?  My thinking that led to this question: I've read that sperm whales number in the hundreds of thousands worldwide; their primary source of food is giant squid.  Prey items usually outnumber their predators by the many thousands, so that means there must be millions of giant squid, and if so, what do they eat?

Answer
Dear Dave,

You are correct that there are probably more giant squid than sperm whales.  There would have to be, or the whales would not be able to use them as a primary source of food.  But the whales do also eat other types of prey, such as fish.  Still, I think you are right that there are probably millions of giant squid out there, wandering in the black depths where we don't see them.

Giant squid also feed on pelagic/swimming prey such as fish and other swimming invertebrates.  So those must be more numerous than the squid.  It's the ol' ecological trophic level pyramid.  In general, one trophic level UP the food chain means a decrease in biomass of about 90% from the previous trophic level (it's a mass game more than a numbers game).  

Hope that helps.

Dana