Pufferfish: Inflating Defences and the Careful Art of Fugu

Photo: Dotun55, CC BY-SA 4.0, via Wikimedia Commons

The pufferfish is built for a very particular defence. When it is threatened, it swallows water or air and inflates itself into a ball that is much larger than its normal shape, which makes it hard for a predator to swallow. The skin is elastic and the stomach can stretch enormously, and some species also have spines that stick out when it swells.

Photo: Raita Futo, CC BY 2.0, via Wikimedia Commons

The second defence is chemical. Many pufferfish carry tetrodotoxin, a powerful poison that is concentrated in organs such as the liver and the ovaries. It is dangerous to people, and there is no simple antidote. The toxin is produced with the help of bacteria that the fish picks up in its food chain.

Photo: Syced, CC0, via Wikimedia Commons

In Japan, the fish is a delicacy called fugu, and preparing it takes real training. Chefs must be licensed before they are allowed to prepare it for customers, and the licence requires years of training and a practical test. The thin slices of raw fugu are delicate and subtle in flavour.

Photo: Richard Ling, CC BY-SA 2.0, via Wikimedia Commons

Pufferfish live in warm and tropical seas, and some species live in brackish or fresh water. They are slow swimmers with small fins, and they use their beak-like teeth to crack shells. Divers who meet one on a reef often get a close look before it floats away.

Photo: Diego Delso, CC BY-SA 4.0, via Wikimedia Commons

Would you try fugu, given the risks? I admit that I would only do it in a restaurant with a very good licence on the wall.