Baleen whales and filter feeders

[DavidPT40]

I read somewhere that whales and large filter feeding fish (whale sharks, basking sharks) can obtain a maximum of about 800 calories per hour while actively feeding on plankton.

So if this number is a maximum, how do whales survive? 800 calories doesn't seem like it would fuel a whale for an hour.

Just for comparison, humans can utilize 1000 calories per hour while running, and about 800 for swimming.

 

[RIOceanographer]

I am not sure where you read that, but it definitely isn't even close to the maximum. I have seen numbers of up to 4 tons (8000 lbs) of krill per day for the blue whale. I am not sure what that comes to in calories, but it is going to be a very large number.

Also, most baleen whales only feed for about 1/2 of the year and then fast the rest of the year when they migrate to their breeding grounds. That means during their feeding season they have to eat much more than they actually burn.

 

[DavidPT40]

I found something similar to what I read. Here it is

"Basking Shark requires about 663 calories per hour just to propel its massive body through the water; when plankton supply falls off during early winter, the Basking Shark can typically consume only 2 pounds of copepods - about 410 calories - an hour. So in winter, a Basking Shark would be using up more energy in swimming than it could get from its food. "

http://www.elasmo-research.org/education/topics/d_filter_feeding.htm

 

[RIOceanographer]

Keep in mind that a basking shark is not warm blooded which is part of the reason why it burns so few calories. Warm bloodedness requires lots of energy. Basking sharks also got their name for their tendency to swim slowly at the surface. Comparing the feeding rates and energy usage of a basking shark to a baleen whale is sort of apples and oranges. Baleen whales can be significantly bigger than a basking shark, and of course they are warm blooded so they need to eat a lot more.

I gave the example of the blue whale above because as the biggest of the whales it probably has the largest appetite of any animal on earth. Here is a site I found that has the same information for the blue whale I gave in my earlier post above, and it has links to information on a number of other whale species as well:

http://www.acsonline.org/factpack/bluewhl.htm

And just for kicks I googled a few sites that gives some calorie usage info for whales.

First the big one, the blue whale comes in with up to about 3 million calories per day:
http://www.dec.state.ny.us/website/dfwmr/wildlife/endspec/blwhfs.html

For the finback I found 800,000 calories per day:
http://www.iwdg.ie/species_profiles.asp?speciesID=2104

Here is one that gives a number of 500,000-1 million calories of the "average baleen whale":
http://www.royalbcmuseum.bc.ca/programs/whales/t-activity-7.html