Video: Suction-Cup Cameras Give Insight Into Life of Humpback and Blue Whales

Researchers at Stanford’s Hopkins Marine Station have been able to provide new insight into the feeding behavior of whales by suction-cupping video cameras to cetaceans.

Blue whales, believed to be the largest animals to have ever lived on Earth, survive by eating krill — some of the smallest. This is a fairly well-known fact, but how they do it is a little more mysterious.

What we do know is that rorquals, a family of baleen whales including blue whales, humpbacks and minke whales engage in lunge feeding. These whales will speed up and then, thanks to a number of special adaptations like triple-hinged jaws, engulf a volume of water larger than their own body — by about 140% — before filtering it back out through their baleen.

Maintaining higher speeds while opening up wide and taking in so much water creates a significant amount of drag. Overcoming this drag, especially at depth, requires a lot of energy.

The big question is: when during this process do the whales open their mouths? Waiting to open their mouths as they reach peak speed will minimize the cost of energy, but opening it slightly before can maximize the amount of prey they engulf.

While research tools equipped with accelerometers, magnetometers and pressure and sound recorders can track the movement of whales in three dimensions, it doesn’t allow for direct observation of feeding, which can take place more than 1,000 feet below the surface. Until now that is.

Stanford researchers created a miniature version of this suction-cup sensor package that includes video recording capabilities so that they can visually document the whales’ behavior during this process (check out the video above).

The team found that rorqual species that feed primarily on krill open their mouths precisely at peak speed and close them when they returned to normal speed. Whales that eat fish, like humpbacks, would vary their timing, opening their mouths at different times. One hypothesis is that these whales are willing to expend the extra effort when eating prey that provides more energy. The team reported these findings in Current Biology.

Information on whales and their environment help develop more effective conservation efforts. Three of the eight species of rorquals are currently endangered, and their feeding characteristics put them all at a higher risk, especially when things like sonar can scare them away from feeding grounds.

“Because they operate on an energetic knife-edge, any changes in the environment related to their food supply could have profound impacts on individual and population health,” said Jeremy Goldbogen, assistant professor of biology at Stanford and co-author of the report.