Natural La Jolla: Magnificent blue whales in our waters for summer

Diving down, a blue whale flukes up. Photo by Jeremy W Smith
Diving down, a blue whale flukes up. Photo by Jeremy W Smith

By Kelly Stewart

The largest animal on the planet, possibly the largest animal to ever exist, is now roaming about in our local waters. Topping out at about 100 feet long and weighing about 100 tons, the blue whale (

Balaenoptera musculus

) is a member of the rorqual family (in the same family as humpbacks). Members of this family have pleated grooves in their throats as well as baleen, which is a set of fringed plates composed of keratin that hangs down from the upper jaw in the mouth, functioning as a filter.

It’s now the summer feeding season, and blue whales are here to forage on krill (a small red shrimplike creature). Blue whales can take in about 4 tons of food per day and although usually they feed at depth, occasionally the concentrations of krill will be at the water’s surface and then it’s possible to see whales exhibiting their lunge-feeding behavior. While rolling onto their sides, the whales take in huge mouthfuls of water that is swarming with krill. The pleated grooves in their throats then expand to capacity and the whales squeeze the water through their baleen while retaining their prey.

A blue-gray color with gray mottling on its back, the blue whale has one very small dorsal fin located quite far back on its body. They also have two blowholes on top of their heads, with a front splash guard to shield the blowholes when they are surfacing. When the whale exhales, misty breath shoots straight up high into the air, and if winds are calm, the blow can linger for quite a while. The blue whale blow (or spout) is unmistakable, and so it’s possible to spot it from shore. These amazing giants should be passing through our local area through early fall.

Kelly Stewart, Ph.D. is a postdoc with NOAA’s Southwest Fisheries Science Center. Contact her at NaturalLaJolla@gmail.com.

Check out the video of blue whales in La Jolla below:

[youtube]http://www.youtube.com/watch?v=LwkmNYc8n8Q[/youtube]

   
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