Slow but agile
The puffer fish uses almost exclusively its pectoral fins to move forward and steers with its caudal fin. Its dorsal and anal fin support it only minimally, which means that the puffer fish is very slow, but remains extremely agile. He can swim forwards and backwards and dive up and down without any problems.
Balloon of the seas
If puffer fish are in danger or feel threatened, they can use their muscles to force water into their stomachs, which causes them to expand into a round ball. In this state, the spines, which normally rest against the fish's body, are directed outward and form small barbs. This protective mechanism should on the one hand scare the predator, on the other hand it is usually not possible for the predator to devour the puffer fish in this form.
The puffer fish carries a neurotoxin in its intestines, especially in the skin and liver, that is highly toxic to animals and humans. This venom is also called tetrodotoxin and paralyzes the entire body in a few minutes, but does not affect brain functions. It is now assumed that the puffer fish does not produce the neurotoxin itself, but takes it in through bacteria in its food.