Ocean Watch: Scorpionfish move slowly but possess poison spines
Although most swimmers don’t see it, the devil scorpionfish is abundant on Hawaii’s reefs.
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While snorkeling with visiting relatives last week, our nephew motioned for us to come see what he found. I swam over and saw a rock. As Brian pointed, I scanned the rock, thinking that whatever he saw had skittered into a hole. But what soon had all of our attention was that fuzzy, frowning rock. Brian had found a devil scorpionfish doing an Oscar-worthy performance as an algae-encrusted stone.
Although most swimmers don’t see it, the devil scorpionfish is abundant on Hawaii’s reefs. Even we avid snorkelers and divers can pass one scorpionfish after another and be totally unaware. One day this summer, I made a point of looking for scorpionfish and spotted four, all a bit different but precisely matching their backgrounds of algae, silt, rock and rubble.
Devil scorpionfish don’t change color and texture to blend in, but instead harbor seaweeds and encrusting marine organisms on top of their bumpy skin. When this camo cloak grows burdensome, the fish sheds the layer and starts over.
Most of the devil scorpionfish’s 12-inch-long body is well disguised, but when it hops, the side fins that the fish rests on show their colors. The bright orange and yellow undersides of those fins is a warning signal to predators.
Devil scorpionfish belong to a family of about 350 species worldwide. Hawaii hosts 28 of those, 10 endemic. All are slow-moving predators with venomous spines in their fins. The notorious stonefish of the South Pacific has the most toxic venom of the family but is not found in Hawaii. The stings of Hawaii’s species hurt but are not medically dangerous.
Other members of this family are the lovely lionfish, which employ the opposite approach of their camouflaged cousins to avoid getting eaten. Lionfish spread their flashy fins to project the message, “Back off or you’ll be sorry.”
The species that’s eating Atlantic and Caribbean reefs out of house and home are not found in Hawaii. That one is native to tropical waters of the South Pacific.
As you might expect, devil scorpionfish are ambush predators, waiting motionless on the ocean floor for some unsuspecting fish or invertebrate to mosey by. The scorpionfish’s lightning strike is so fast, it’s nearly impossible to see.
I once found a devil scorpionfish that was remarkably visible because it had just bitten a damselfish, still wiggling and positioned sideways in the scorpionfish’s mouth. The predator sat motionless, patiently waiting for the unfortunate damselfish to die so the scorpionfish could manipulate it into a headfirst swallow.
I prodded Brian’s scorpionfish (with a rock, not my hand) to get a glimpse of those orange fins, so different from the rest of the nearly invisible fish. Then three of us dived down over and over, pointing my camera at the fish every which way.
We got a lot of good shots. But then, it’s pretty easy to take pictures of a rock.