Inflation is not a party trick and it costs the fish more than people assume.
A porcupinefish has no ribs and no pelvic girdle, and its stomach has been rebuilt into an elastic sac. Threatened, it pumps water into that sac in fast gulps until the body is a rigid ball, the skin stretches, and the spines - which are modified scales, lying flat against the body the rest of the time - are forced upright. A predator now faces something several times wider than what it was chasing, covered in points, and usually gives up.
Doing it is expensive. The fish cannot swim properly while inflated, it takes a long time to deflate and recover, and a fish made to inflate repeatedly for a camera can be left exhausted and vulnerable for hours. A pufferfish lifted into the air will also take in air, which it may not be able to expel at all. This is the reason the reef-safe rule exists: you do not touch them.
The chemistry is the second layer. Parts of the body carry tetrodotoxin, the same nerve poison as in the pufferfish, so a predator that gets past the spines has a further problem.
It spends the day in a cave or under a ledge and comes out at dusk to crush urchins, snails and crustaceans with fused beak-like teeth.
The genus. Diodon Linnaeus 1758 - di- (two) + odon (tooth). ETYFish
The species. Diodon liturosus Shaw 1804 - blotched or patched. ETYFish
- light brown to sandy body with large dark blotches ringed in white
- short spines that lie flat until the fish inflates
- no dark band between the eyes, which separates it from the long-spined porcupinefish
- large round eyes and a permanently open mouth
- up to 65 cm
Why it's threatened
There are no known major threats.
Threat classification from the IUCN Red List.
