Porcupine Puffer Fish

Picture credit : Simon Dowling

Diodon Hystrix, is know by many different names., The Spot-Fin Porcupinefish, Spotted Porcupinefish or most commonly the Black Spotted Porcupinefish. In contrast to most juvenile fish, it lives in the open ocean until it grows to about 20cm long. Then it will generally prefer to make its home within the confines of a coral reef to live out its adult life.

Like all Porcupinefish, they have very strong jaws and beak-like teeth. All the teeth in the upper jaw are fused into a single plate, and all the teeth in the lower jaw are fused into a single plate. Its family name in Latin (Diodontidae) means “two teeth,” reflecting the single tooth plate that these fishes have on each jaw. They are foraging predators, tending to pick on their prey in the sand, feeding on hard-shelled or spiny invertebrates, like urchins, snails, and crabs.

When they feel threatened, the Black Spotted Porcupinefish swallows water and erect its spines along its body until it looks like a large, spiny balloon. Though the process takes a few seconds, when complete, it is almost 100% effective at preventing predators from eating eat. When the Porcupinefish no longer feels threatened, it uses muscles along its abdomen to push the water back out of its mouth. It can be toxic to potential predators, so this species is rarely eaten on the reef and usually avoided for easier prey.

At our artificial site “Junkyard“, you can see many Porcupinefish. Usually hiding from scuba divers among the various structures they are quite shy and retreat if you get too close. Recently, however we have observed one which is incredibly friendly. When divers are at the site, the Black Spotted Porcupinefish (which we have named “Steve”) will get extremely close, hoping that sand movement will uncover some crustacean snacks for him to munch. He is completely unafraid of divers, and because of his behaviour has led to divers attempting to interact with him against our “look but don’t touch” policy.

We released a video to ask divers to enjoy his company, but leave him to his natural state. This way, we can enjoy Steve for a long time to come.

If you would like to visit Steve and help maintain his home at Junkyard, have a look at our Eco Courses page.