Nothing on this reef eats an adult puffer, and this is the biggest puffer there is. At 1.2 m (4 ft) it outgrows every other pufferfish in the world, and a large one working along a drop-off in the open, slowly, in full view, is behaving exactly like an animal with nothing to run from.
The young are a different animal in a different place. A juvenile is boldly marked with dark stripes across the belly and lives on weedy inner reef, in estuaries and over sand; the adult is white to gray, evenly dusted with small black dots, out on clear lagoon and seaward reef. The two are rarely in the same water, and the change catches out even experienced guides. The dots are the stripes: as the fish grows, the lines break apart into spots.
Inflation is hydraulic, not air. Threatened, the fish pumps water into a highly elastic stomach diverticulum until it is a rigid sphere several times its normal volume, at which point almost nothing can get its jaws around it. The skin has no scales to get in the way, the ribs are reduced so the body can expand, and the whole operation takes a few seconds. Lifting a puffer out of the water to make it inflate with air is a good way to kill it.
The chemistry is what everyone knows and few explain. Pufferfish tissue carries tetrodotoxin, produced not by the fish but by bacteria it accumulates through its diet, and there is no antidote. It is over a thousand times more toxic than cyanide by weight, which is why fugu preparation is licensed work in 🇯🇵 Japan and why nothing on the reef bothers an adult puffer.
The four fused teeth form a beak that crushes coral, molluscs and urchins, and grow continuously to keep up with the wear. There are no pelvic fins at all: the fish steers on its pectorals and sculls with the tail, which is what makes that slow, deliberate progress recognizable from a long way off.
The species. Arothron stellatus (Anonymous 1798) - starry. ETYFish
- very large puffer, white to gray, evenly dusted with small black dots
- juveniles boldly striped across the belly, and on weedy inner reef rather than out on the coral
- no pelvic fins; steers with the pectorals and sculls with the tail
- cruises slowly in the open instead of hiding
- length up to 1.2 m
Why it's threatened
Threat classification from the IUCN Red List.
