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Bubble nets at home

By David Shaw, 2 May 2019

If you thought humans were the only fishers who use nets, think again! Humpback whales work together to net and herd fish, making the fish easier to eat. But these whale nets are made of bubbles! To learn more, it’s time to blow some bubble nets ourselves.

You will need

• Large mixing bowl
• Hole punch or scissors
• Paper
• Straws
• 1/3 cup measuring cup or ladle
• Strainer (optional)
• A few people to help you fish

What to do

1. Half fill the bowl with water – this is your ocean.
2. Next you need some fish. Punch some holes in paper with a hole punch and collect the confetti. If you don’t have a hole punch, you can use scissors to cut 5 mm squares.
3. Sprinkle about half of your paper ‘fish’ onto the water.
4. Pretend to be a whale! Try to catch as many ‘fish’ as you can with the measuring cup.
5. Scoop out the ‘fish’ from the cup, and put them on paper to count them. (Tip: It’s easier if you use a strainer to get rid of excess water from the ‘fish’, before transferring them to the paper.) How many ‘fish’ did you catch?
6. Next, you’ll need more whales. Get some people to help you. Give them a straw each and arrange yourselves around the bowl.
7. Sprinkle more ‘fish’ on the water so you have the same amount as before.
8. Ask everyone to start blowing bubbles in the water, and try to herd the ‘fish’ into a tight group.
9. Tell everyone to stop, and then quickly catch as many ‘fish’ as you can with the cup.
10. Once again, scoop the ‘fish’ out of the cup and count them. Was it easier to catch ‘fish’ with a bubble net?

What’s happening?

Humpback whales use bubble nets to concentrate prey
Image: Christin Khan, NOAA / NEFSC

Bubble net feeding is a cooperative feeding technique used by humpback whales. It’s used to catch large groups of small fish and krill. Bubble nets are a technology that was invented by whales, and it is not instinctive – it needs to be learned.

Bubble net feeding usually requires multiple whales – at least two are needed, and groups of up to 60 have been observed. The net starts with several whales swimming in circles, blowing bubbles around the prey.

When everything is ready, one whale will call loudly to signal to the others that it’s time to feed. The whales all call loudly in response and rise up with mouths open, catching as many fish as they can. Whales can swim faster than bubbles rise, so the net is still in place while they feast.

Scientists are not sure exactly how bubble nets work. Fish could probably swim through a wall of bubbles, particularly if their lives depend on it. New research suggests that it’s not just bubbles keeping the prey confined. The calls that whales make while hunting might combine with the bubbles to make a wall of sound. Either way, it’s pretty amazing!

More information

Watch a video of bubble net feeding in the Antarctic
Check out these whale poems

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