Tag Archives: porcupine fish

Shoreline gems offer a palatable mystery

Published March 18, 2017 in the “Ocean Watch” column, Honolulu Star-Advertiser ©2017 Susan Scott

It’s still unknown how these porcupinefish palates found on the North Shore by a reader change color from white to shades of amber. ©2017 Susan Scott

Last week, reader Chris emailed a photo of some caramel-colored nuggets that she and husband Matt found along a North Shore coastline. Some of the pebblelike pieces are symmetrical, with a centerline. Others are halves of these, and all bear the markings of former ridges.

The ocean had rotated and polished the stony bits into jewels, lovely as the gemstones we call tiger’s-eye. Chris wondered if I knew what they were. I did not — and the search was on. Chris, Matt and I looked in books, queried friends and searched the internet.

The couple’s friend guessed their finds might be parts of parrotfish throats, called pharyngeal mills, that grind up coral rock. They aren’t, but it gave Chris and Matt a search subject that produced a link from Sydney’s Australian Museum. Pictured there is what the museum identified as a spiny pufferfish palate from a beach in the Gulf of Carpentaria.

Hawaii hosts a pufferfish with spines that we call a porcupinefish. The largest grows to a whopping 28 inches long and weighs 17 pounds, 12 ounces (the state record).

Chris and Matt wondered why porcupinefish mouth parts would be concentrated in one area of a long beach.

It’s possible that porcupinefish are abundant in that part of the ocean, but it’s more likely that the deposits are a result of coastal currents. The ocean sorts pebbles and shells according to flow strength, shoreline shape and objects’ weights, and that area is where the water drops off its palates.

I wondered why the roof of the mouth of the big prickly fish outlasts other parts of its skeleton, but I didn’t wonder for long. I have found dead, desiccated porcupinefish on beaches and brought them home.

When I picked one up to examine its palate, the whole thing fell apart, jaw bones included. That made clear that the fish’s upper tooth, shaped like a curved razor, is fused to a ribbed rock-hard palate. The same-shaped lower tooth is also fused to an identical hard floor, an upside-down palate. Both are bone white.

Apparently, after a pufferfish dies, ocean tumbling wears away its softer bones and teeth, leaving only the solid, durable plates. Where they get their rich color is a mystery.

Porcupinefish use their formidable teeth and rock-hard palates to crush snails, sea urchins and crabs. Be wary of a trapped porcupinefish. If caught or cornered, the fish can easily take off a finger, bone and all. Of the fresh bite I once saw, the remaining forefinger was sliced as clean across as if done with a cleaver.

Chris and Matt invited me to come see their pufferfish palates and, seeing my awe, generously gave me a few. Forget diamonds, rubies and sapphires. For us, porcupinefish palates are far more precious than stones.

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