Big Gulps

How Whales get their daily (and rather hefty) meals

 

BUBBLE NETTING

By Dr. William Gough

Postdoctoral Researcher, Marine Mammal Research Program Lab, Hawai'i Institute of Marine Biology

What is it? 

Bubble-netting is a specialized foraging technique that involves swimming in a circular pattern below the water’s surface and releasing pulses or curtains of bubbles to corral small prey such as krill or fish into a tight ball, allowing for easier and more efficient capture. Humpback whales are the only species known to perform this behavior, and they are able to modify the bubble formation in different circumstances to capture different prey species.

Who does it? 

Humpbacks are the only species known to use bubbles in this particular way.

What’s the point? 

Bubble-netting is a time-intensive process, leading to fewer mouthfuls of food in a given period of time versus an animal feeding without bubbles. As a result, there are multiple theories on the overall efficiency and decision-making behind bubble-netting. What does appear to be clear is that the use of bubbles as a modifiable “tool” allows these whales to constrain their prey into a small area and keep them from escaping during engulfment.

 

 

BOTTOM FEEDING

By Dr. David Wiley

Research Ecologist, NOAA's Stellwagen Bank National Marine Sanctuary

What is it? 

Bottom-feeding is a technique developed by humpbacks to catch small, fast-swimming fish called sand lance that often hide buried in the ocean bottom. The technique requires humpbacks to dive to the seabed, roll onto their side, flush the fish from hiding, and use their giant mouths to engulf the escaping fish. While a whale can bottom-feed alone, the technique seems to work best in groups, with whales orienting head-to-head to corral the escaping fish. 

Who does it?

As far as we know, humpbacks are the only whales that use this technique, and it has only been observed for humpbacks feeding on sand lance in the Gulf of Maine. 

What's the point?

In the ocean, predators and prey play a crucial game of hide-and-seek, with the life of each depending on the outcome. Sand lance bury themselves in the seabed to stay safe from predators, which requires the whale to develop techniques to flush them from hiding so they can be captured and eaten.

LUNGE FEEDING

By Dr. Jeremy Goldbogen

Associate Professor of Oceans, and by courtesy, of Biology Hopkins Marine Station of Stanford University

What is it? 

Lunge-feeding is used by the largest whales to feed on aggregations of small prey like krill or fish. Lunge-feeding has multiple steps:

1. The Lunge: An acceleration to high speed
2. The Engulfment: Engulfment of an extremely large volume of prey-filled water
3. The Purge: Purging of engulfed water out of the mouth using a baleen filter that lies between the jaws
4. The Gulp: Swallowing of prey that remains inside the mouth
   

Who does it? 

• Bryde’s Whale (Balaenoptera brydei + Balaenoptera edeni)
• Sei Whale (Balaenoptera borealis)
• Omura’s Whale (Balaenoptera omurai)
• Blue Whale (Balaenoptera musculus)
• Humpback Whale (Megaptera novaeangliae)
• Fin Whale (Balaenoptera physalus)
• Antarctic Minke Whale (Balaenoptera bonaerensis)
• Common Minke Whale (Balaenoptera acutorostrata)

What’s the point? 

The largest whales have the daunting task of feeding an enormous body. Lunge-feeding allows whales to forage on extraordinary amounts of prey. Each lunge is an acrobatic event that captures hundreds to thousands of prey in each gulp. Whales daisy-chain lunges together during long dives deep into the ocean, where prey is the most densely packed. When prey is highly abundant, whales will perform dozens of dives to capture several tons of prey daily.

 

Feature image by Justin Hofman | @justinhofman