Dive Dry with Dr. Bill

#249: Sting of the Scorpion(fish)

There aren't many species in our waters that one needs to be concerned about. Despite all the hype following "Jaws," great white sharks are a rare sight in our waters. Usually they are seen near the surface from boats, and not by divers underwater. Heck, I've been diving Catalina off-and-on since the late 1960's and I have yet to see one underwater here, only when cage diving at Guadalupe Island off Baja. I'll readily admit, they were a big fear of mine when I moved to the island from the East Coast... but their threat is highly exaggerated, and I stopped worrying about them long ago.

However, there are a few species that can give you a nasty sting, bite, puncture or jolt when you're underwater. Of course they won't make you lower on the food chain than they are by eating you. Jellyfish, and their relatives like some hydroids, can sting you. However, they are fairly rare here. The Pacific electric or torpedo ray can give you a stunning jolt of electricity, but I have yet to have one do this even when I'm filming them even within a foot or two.

However, the California scorpionfish is one species to avoid... if you can actually see it in time. These fish are experts at camouflage, and sit motionless on the bottom resting and waiting for food to wander too close to their mouths. By blending into their surroundings, they generally avoid detection. If a predator, or an unobservant diver, makes contact with them, they employ their other line of defense... sharp spines on their dorsal fin which carry a toxin. Although I've never made contact with one, I know of divers who have... and it can be painful.

The California scorpionfish is found from Santa Cruz south along the Baja coast and into the Gulf of California (Sea of Cortez) in depths from the intertidal to 600 feet. Although scorpionfish prefer hard, rocky bottoms, they can also be found on soft substrates like sand or silt. They are thick-bodied fish with large fins. Their color is variable, allowing them to blend in with their surroundings. It ranges from a bright red to a light brown, and the body has many dark spots on it.

These fish reach a length of nearly 18 inches, and may live up to 21 years. Apparently they prefer crabs as a main course, but are known to eat shrimp, octopuses and small fish. One of the reasons they are seen resting during the day, is they are usually nocturnal or night time feeders. These fish have been the target of a fairly important commercial fishery in the past, but it has declined over the last half century. One of the more active groups are the dory fishers off Newport Beach. They are favored by Asian diners, and form part of the live fish trade in their markets and restaurants.

Scorpionfish are sexually mature at about two years and 8" in length. Quite precocious! During late spring and early summer, the mature adults move into deeper water (100 to 400 ft) and form huge spawning aggregations. I guess they prefer a little privacy when they mate, and generally keep away from Dr. Bill's prying camera lens. According to Dr. Milton Love, they may migrate as far as 220 miles to spawn. My profile criteria on searches for lady "go-divers" within 50 miles! Maybe I should expand my search parameters?

Although they form their mating groups in deep water, they swim towards the surface to actually release their sperm and eggs. Dr. Bill has to do the same unless he is seeking membership in the Five Fathom Club. Females produce interesting egg capsules which are gelatinous and float near the surface. They take less than a week to hatch. The young are found in shallow water, often under thick seaweed for protection.

Dr. Love states that the poison injected through this fish's dorsal spines is fairly toxic. Some of their tropical relatives can cause death, but our local species is generally non-lethal. It is still potent after the fish is dead, and even after it has been frozen so exercise caution. The toxin is produced in glands near the base of the spine. If you are unfortunate enough to place your hand on one of these accidentally, it can be quite painful. Hot water is advised to reduce the pain since it denatures or breaks down the toxin. I guess this is one situation in which a hot tub or jacuzzi after diving might be helpful, despite the increased risk of the bends.

© 2007 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 49, 10:00 AM and 5:00 PM weekdays. Please help me climb out of self-imposed poverty... buy my "Munching and Mating in the Macrocystis," "Great White Sharks of Guadalupe," "Calimari Concupiscence: Mating Squid, " "Playful Pinnipeds: California Sea Lions," "Belize It or Not: Western Caribbean Invertebrates, Fish and Turtles," "Gentle Giants: Giant Sea Bass" or "Common Fish and Invertebrates of the Sea of Cortez" DVD's. Yes, take Dr. Bill home with you... we'll both be glad you did!

The large eyes of a scorpionfish, good... and bad camouflage patterns,
a scorpionfish backflushing its gills (also used as a threat gesture).

This document maintained by Dr. Bill Bushing.
Material and images © 2007 Star Thrower Educational Multimedia