Blowfish Aren't Actually Holding Their Breath

Contrary to popular belief, blowfish aren't actually holding their breath when they're puffed up, according to a new study.

Pufferfish, also known as blowfish, can quickly balloon their bodies to the size of a football by gulping water into their elastic stomachs. And while it turns out they can still breathe during this expanded state, the deflation process may make them easy targets for predators.

"We were intrigued by previous studies that suggested the pufferfishes hold their breath while inflated, presumably to keep the ingested water in the stomach," lead researcher Georgia McGee told Live Science. "If this was true, we thought it likely that pufferfish inflation would have a limited duration, due to a lack of oxygen getting to vital body organs."

To test the theory, McGee and her colleagues collected eight black-saddled pufferfish (Canthigaster valentini) from Australia's Great Barrier Reef and induced their puffing abilities while in a sealed tank. When they ballooned to about four times their normal size, the scientists measured the amount of oxygen in the tank to determine whether the fish were holding their breath.

It turns out they weren't, and while inflated they're actually quite good at taking up oxygen through their gills, McGee noted.

Biologists believe that these marine animals developed their "inflatability" to gain a faster and better swimming technique. According to National Geographic, when at normal size, they are typically slow and clumsy and vulnerable to predators.

Ironically, however clever this trick may be, it may also leave them utterly defenseless, creating a no win situation.

When puffed up, the fish's oxygen uptake increases to five times that of resting levels, therefore it takes about 5.6 hours for them to deflate and return to typical metabolic levels. And while pufferfish come equipped with deadly poison, it may not be enough to ward off predators when they are too tired to fight back.

"It is kind of like a human athletics race," McGee explained. "Once we have finished the race, we need some time to recover before we can perform to the same level again."

The findings, published in the journal Biology Letters, change our perception of pufferfish, though watching them turn into giant balls is no less amusing, as the movie "Finding Nemo" shows.

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