Meet the Puffers

Some of the fish you meet on the reef seem like cartoon characters. There are the rail-thin trumpet fish, the doe-eyed squirrelfish, the rectangular boxfish and the shape-shifting octopus. And then there's the Tetraodontidae family. They go by many names: pufferfish, balloonfish, blowfish, bubblefish, globefish, swellfish, toadfish, toadies and sea squab. Regardless of what they’re called, these fish are best known for their unique ability to expand and take on the appearance of spiked balloons. Puffers are common in tropical oceans around the world, with more than 120 species in the family. They’re easy to find and fascinating to watch. So let’s meet some of these inflatable “soccer balls of the sea.”

You might not recognize a puffer if you are looking for a fish that resembles a spiked ball. Unlike its cousin the porcupine fish, which always shows its spikes, the puffer keeps the onboard armament concealed until it feels stressed or threatened. Most of the time, puffers resemble oversized tadpoles, with an oversized head that sports thick lips and large bulging eyes that give these fish a puppy dog-like appearance.

Puffers come in a wide range of sizes, from the dwarf puffer, which is often less than an inch in length, to the starry puffer, which grows up to lengths of four feet. They are scale less and usually have rough to the spiky skin. Their characteristically large heads are needed to make room for powerful jaw muscles that work large teeth fused into upper and lower plates. These beak-like growths are used to crush the shells of crustaceans and mollusks, which are the puffers' primary food. Larger fish can sometimes be seen using their teeth to crack open clams, mussels and other shellfish. But unless it's feeding, you won't see a puffer's teeth, because they are covered by large pouty lips. Unlike collagen-enhance Hollywood starlets, a puffer's outsized are utilitarian rather than ornamental, as they are used to taste and feel a potential meal before taking a bit. This ensuring ensures the puffer isn't wasting energy chomping into something inedible like an empty shell, or accidentally breaking its teeth or jaws trying to break open a rock that it mistakes for a shellfish.

One of the more distinctive characteristics of the puffer is the wide-set and bulging eyes. Puffers have very sharp vision. This is an important survival strategy that both helps the puffer spot small prey and allows it to identify potential threats from farther away. Another ocular advantage puffers have is the ability to move each eye independent of the other, scanning for threats across a wide range of vision. Both eyes can also be directed forward to provide superior depth perception. Some puffers have eyes with green iridescent layers, positioned to reflect bright sunlight from above while still allowing ambient light from the surrounding environment objects to filter in. It’s the aquatic equivalent of mirrored sunglasses.

Puffers won’t win any swim races. Their relatively small pectoral and dorsal fins are designed to allow them to maneuver methodically around the reef as they search for snacks. As compared to most fish, a puffer's swimming style is more like a hovering helicopter that a moving airplane. This slow, measured pace allows pufferfish to spot and capture prey that most other fish would simply swim right past. Most of the time, the puffer's large tail fin is used like a rudder to help the fish maneuver in close quarters. But when danger looms, the puffer can also use its tail fin to create sudden short bursts of speed and find refuge in a crevice within the reef. This talent for rapid acceleration, combined with excellent vision, allows the puffer to anticipate and escape many threats without having to resort to its other defense systems. 

If a predator is quick enough to actually snag a puffer, the attacker won’t feel lucky for long. Pufferfish are generally believed to be the second-most poisonous vertebrates in the world, after the golden poison frog. Certain internal organs such as the puffer's liver and sometimes the skin contain tetrodotoxin, a poison that at the very least creates a foul taste, and is more often lethal. Tetrodotoxin is deadly to humans—more than 1,000 times as poisonous as cyanide. One pufferfish contains enough toxins to kill more than 30 people, and there is no known antidote. And yet, despite the lethal nature of the puffer, its meat is considered a delicacy in some parts of the world. Known as fugu in Japan, pufferfish meat is prepared by licensed chefs who are trained to carefully cut around the poisonous parts. But even one bad cut can spell almost certain death for those who partake of this toxic treat. In recent years, a new industry in farm-raised puffers has resulted in fish that have few or no toxic substances. This change is attributed to the understanding that puffers synthesize their toxins form bacteria found in their natural diets, but not in commercial fish food.

When escape is impossible, and toxic tastes don't deter an attacker, only then will the puffer employ its ultimate trick. Thanks to its highly elastic stomach, a puffer fish can swallow large amounts of water or air in very short order, inflating itself to two or even three times normal size. This upsizing makes it much more difficult or even impossible for the would-be predator to get its jaws around the now balloon-like victim. In addition to inflating, many puffers also raise ridges of sharp spines as an added deterrent, giving their tormentors an unappealingly spikey package to bite into. This puff-up ploy is used only in desperation, as the process can be quite stressful, and an inflated puffer loses most of its swimming ability.

Puffers are plentiful. Though certain species are vulnerable to water pollution, habitat loss and overfishing, most world-wide populations remain stable. It’s almost a given that you will find pufferfish on a tropical reef. When you do, take a few minutes to observe their routine. Just don’t expect these fish to put on a performance of their signature talent for inflation, as this is actually a fairly rare occurrence during the puffer’s average day. Consider yourself lucky if you do witness this phenomenon, but don’t provoke their defense mechanism for your own amusement. Deliberate attempts to get a puffer to puff up are usually frowned upon; some say it causes undue stress to the fish. But a more compelling reason to abstain may be that repeated goading may cause the fish to start shying away from divers, depriving others of the chance to encounter this wonderful fish. So the next time you see a puffer on the reef, look but give it a bit of space.