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Ocean Watch
By Susan Scott
Monday, August 28, 2000
DURING a recent family visit to the Pacific Northwest, I broke away early to visit one of my favorite places, the Seattle Aquarium. This facility is always fun for me because it features marine animals we don't see in Hawaii. I enjoy the big starfish, am entertained by the sea otters and marvel at how salmon can find their way home. Reading the
signs in SeattleThis time, the descriptions of several other fish caught my attention. One sign discussed the ability of our little tropical cowfish to kill themselves.
No, cowfish don't get depressed -- but their fear can be deadly.
Cowfish are 5-inch long members of the trunkfish family. Like their trunkfish cousins, cowfish bodies are bony boxes; only their fins, eyes and mouths are moveable.
Besides their colors, cowfish are distinct from other trunkfish by bearing several hornlike projections. The two on their heads give the little fish a bovine appearance, thus the common name of cowfish.
THE armor and spines of cowfish are means of protection, but these -- and most other trunkfish -- also protect themselves by secreting a potent poison from the skin when alarmed.
Aquarists like the endearing little cowfish for their kissing mouths and tame demeanor, but keeping them with other fish, even in a big tank, can be a problem. If the cowfish gets anxious, it releases its toxin, which can wipe out the entire tank. Because it is not immune to its own poison, the cowfish dies too.
Another sign that slowed my progress through the aquarium was an explanation next to a tank containing what was labeled a Hawaiian Stonefish, or Scorpaenopsis diabolus. The sign said this species carries deadly venom.
Oops. The common name of this fish is actually the devil scorpionfish, and although a sting from it hurts like mad, it is not lethal to humans.
Hawaii has no stonefish, but the mistake is understandable. In Tahiti, stonefish are called nohu. When ancient Tahitian immigrants came to Hawaii, they named the larger of Hawaiian scorpionfish, which resemble stonefish, nohu. These are two distinct species, however, and Hawaii's nohu has milder venom.
True stonefish are found in the tropical waters of the Indo-Pacific and are notorious for killing people. In Australia, people sometimes call stonefish the step-and-a-half fish because if stung, that's as far as you get before dying.
Fortunately, this is an exaggeration. Only four deaths have been recorded throughout the world from stonefish stings and none of these were in Australia. Stories about stonefish are much more abundant than the fish themselves.
ANOTHER description that intrigued me in Seattle's aquarium was that of an electric eel several feet long. Electric eels breathe air, the sign said.
Electric eels absorb oxygen through their mouths, which are rich in veins and arteries. Besides containing profuse blood vessels, an eel's mouth is also lined with convolutions and projections, thus giving it a large surface area. The efficiency of the eel's mouth in obtaining oxygen had caused its gills, over evolutionary time, to disappear. Therefore, if you hold an electric eel underwater for more than a minute, it will drown.
Electric eels are freshwater fish found in shallow streams of the Amazon region. Their abilities to breathe air and shock prey and predators make them some of the most unusual fish on the planet.
Because I have been to the Seattle Aquarium several times, I considered skipping it during this visit. I'm glad I didn't.
Marine science writer Susan Scott's Ocean Watch column
appears Mondays in the Star-Bulletin. Contact her at honu@aloha.net.
