Tag Archives: spines

Puffer fish armed with toxin in addition to its spiny body

Published October 5,, 2015 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2015 Susan Scott

A dead ulua, or jack, washed up on Kailua Beach recently after having tried to ingest a porcupine puffer fish, which inflated and stuck in its throat. ©Greg Turnbull

A dead ulua, or jack, washed up on Kailua Beach recently after having tried to ingest a porcupine puffer fish, which inflated and stuck in its throat. ©Greg Turnbull

Kailua resident Greg Turnbull sent a picture of a freshly dead, 36-inch-long fish he found on Kailua Beach during a recent dawn walk. Greg thought the fish was an ulua (jack), and I agree. Although it’s unusual for a big jack to wash up on an Oahu beach, that’s not what drove Greg to take the picture. The gaping ulua had an inflated porcupine puffer fish stuck in its throat.

The puffer fish made a fatal mistake. Swelling up in a predator’s throat is a good ploy to prevent being swallowed, but step two is crucial. The puffer must shrink and run before the suffocated fish washes ashore.

People call the 120 or so species of puffer fish several names — balloon fish, blowfish, globefish, toadfish — all referring to their famous defense: an elastic stomach. When threatened, a puffer engorges its stretchy stomach with water or, if a predator drives the puffer to the surface, air.

Susan holding a puffer fish. Courtesy Craig Thomas

Susan holding a puffer fish. Courtesy Craig Thomas

The idea is to grow too big for a predator’s mouth. If the pursuer has a really big mouth, the puffer sticks in the fish’s throat. Because fish breathe by taking water in the mouth and expelling it out the gills, a throat full of puffer fish is deadly.

Another deadly puffer defense is the ability to store a poison called tetrodotoxin. In the ocean, puffers eat plants and animals that contain naturally occurring bacteria that manufacture tetrodotoxin. By choosing food that doesn’t contain those bacteria, aquaculturists can raise poison-free puffer fish.

Tetrodotoxin is well known for being so potent that a tiny dose can kill a person in minutes. The poison blocks sodium channels in nerves, and when sodium can’t enter a nerve cell, it can’t tell muscles what to do, such as breathe. There’s no antidote to the toxin, but, because it wears off by itself, artificial breathing can save a victim.

Ulua (Jack). Courtesy Russell Gilbert

Ulua (Jack). Courtesy Russell Gilbert

So, I wondered, are jacks immune to tetrodotoxin?

Hard to say. Puffer fish have been found in tiger shark stomachs, and the Internet has pictures of a snapper, frogfish, loggerhead turtle and duck eating a puffer fish, but it’s unstated whether the animals lived or died. What I did learn, however, is that the sodium channels in some snails, crabs and presumably tiger sharks are unaffected by tetrodotoxin.

I also learned in my reading that 19th-century warriors from the Gilbert Islands (today Kiribati) wore what a British explorer in 1847 called “an extraordinary looking apology for a helmet.” The illustration shows a porcupine puffer fish skin on the head of a warrior. Apparently the man mistook a fish for a hat.

Thanks, Greg, for sharing your picture. It’s great food for thought.


Marine biologist Susan Scott writes the newspaper column, “Ocean
Watch”, for the Honolulu Star-Advertiser, www.staradvertiser.com

©2015 Susan Scott

 

If fish’s spikes don’t get you, it’s razor-sharp teeth might

Published June 8, 2015 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2015 Susan Scott

Porcupinefish — related to puffer fish — improve on the defensive adapta-tion of inflation with pop-out spikes. These were found on Leeward Oahu’s Maili Beach. Courtesy Kimberly Coffee-Isaak

Porcupinefish — related to puffer fish — improve on the defensive adaptation of inflation with pop-out spikes. These were found on Leeward Oahu’s Maili Beach. Courtesy Kimberly Coffee-Isaak

A photo arrived in my inbox recently with a note from Kane­ohe reader Richard, whose friend Kimberley found an object on Wai­anae’s Maili Beach that baffled them both. Richard wondered whether I knew what it was.

Courtesy Kimberly Coffee-Isaak

Courtesy Kimberly Coffee-Isaak


Courtesy Kimberly Coffee-Isaak

I did, but not from my Hawaii experiences. While exploring the Sea of Cortez (Gulf of Cali­for­nia), I found the white spikes so common on Baja’s desert beaches that I often wore shoes to protect my feet. The little spears were in all stages of decay, from newly dead to Kimberley’s wad of spines held together only by dried skin. They were porcupinefish.

Porcupinefish and puffer fish are closely related but have one big difference. When threatened, both family members puff up with water in hopes of making their bodies too big for a predator to swallow. But the well-named porcupinefish have added security. Embedded in their skin are sharp, 1- to 2-inch-long spines.

porcupine fish

Porcupine fish. Courtesy David Schrichte.

Porcupinefish spines lie flat against the fish’s body. When the fish is threatened, though, it inflates its body with water and out pop the spikes.

One kind of porcupinefish is called a burr fish because its short spines permanently stand up, like rose thorns. Hawaii hosts one burr fish and two porcupinefish, which can be found throughout tropical waters.

Burr fish. Courtesy David Schrichte.

Burr fish. Courtesy David Schrichte.

The point of puffing up is to become a ball too big to get down the throat, and spikes on the ball are even more off-putting. But that doesn’t stop some fish from trying. People have found inflated porcupinefish stuck in the throats of dead marlins and tiger sharks.

Porcupinefish and puffer fish have another well-known defense. They carry bacteria that manufacture the nerve poison tetrodotoxin, which the fish store in their skin and organs.

puffer

Pufferfish. Courtesy David Schrichte

Puffer fish nerves aren’t susceptible to tetrodotoxin, nor are the nerves of their main predators, sharks and billfish. The poison works on other species, though. Tetrodotoxin sometimes kills people who eat the Japa­nese puffer fish dish called fugu.

If all else fails, porcupinefish bite with the efficiency of a guillotine using two razor blade-type teeth, one upper, one lower. Porcupinefish have bitten off the fingers of several Hawaii fishermen and divers who dared to come too close.

Porcupinefish balloon out by sucking water in, and they also blow it out. Their strong water jets uncover meals of snails, crabs and shrimp buried in the sand.

I can’t answer Kimberley’s question as to how it happened that this was all that was left of the fish on the beach. I’m just glad she spotted the long-dead puffer fish before stumbling foot-first onto its spines.


Marine biologist Susan Scott writes the newspaper column, “Ocean
Watch”, for the Honolulu Star-Advertiser, www.staradvertiser.com

©2015 Susan Scott