Dive Dry with Dr. Bill

018: Shovelnose Guitarfish

Last weekend I was at 70 feet, panning my camera down the length of a very long kelp blade. As I approached the tip of the blade, I noticed the outline of something buried in the sand. Near the middle was a pair of eyes and two holes leading into the gills. I quickly recognized a fish that I hadn't seen in several years... the shovelnose guitarfish (Pe guitarra or pez diablo as it is known in Mexico). These fish are truly one of the more unusual characters encountered underwater. In certain areas of Mexico they are dried and sold as souvenirs, looking like a devil.

Shovelnose guitarfish are distributed from central California to the Gulf of California (Sea of Cortez), Mexico. They are known from fossils dating back 100 million years. Although generally found in shallower waters above 40 feet, they may be seen as deep as 300 feet. They sometimes are found in large groups.

Guitarfishes are rays, not sharks (one of their close relatives). The pectoral fins in rays like this, and the bat ray, are attached to the head. The eyes are on the top or dorsal surface of the head so they can see clearly even when the fish is buried in the sand. Their gill openings are located near the eyes so sea water can be taken in, filtered by the gills for oxygen and passed out through the gill slits on the underside of the body.

These rays spend most of their time resting on the bottom, often buried in the sand like this one. It is said that these rays can change colors to match their surroundings. This camouflages the fish, allowing them to "jump" on unwary prey that comes too close. Here they feed on animals that live on or in the sand including fish, crabs, shrimps and worms. These guitarfish have been observed feeding on sand crabs in waters just a few inches deep.

This species may reach 5 1/2 feet in length and 40 pounds. Its long, pointed snout distinguishes it from other guitarfish. Mating occurs during the summer months. Females give live birth to as many as 28 fully-formed miniatures (about 6" long) the following spring or summer. Like other rays and sharks, the male has reproductive structures known as claspers on its underside.

Formerly considered undesirable by-catch by commercial fishermen, guitarfish are now the target of a minor fishery. The flesh on their tails and backs is considered good tasting. Their remains are somewhat common in Native American middens.

Dr. Milton Love at UCSB reports one incident in which a shovelnose guitarfish actually attacked a diver. Apparently the diver interrupted a male while he was courting his female. The ray swam towards the diver and rammed him. These guitarfish lack sharp teeth so there is little chance they could inflict any real damage. The one I encountered was alone. After a few minutes of videotaping it at very close range, it finally bolted, swimming away at a very fast pace. It was probably in search of a mate. Not a bad idea! I've been trying to locate a "mermaid" for years.

© 2003 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.

Image caption: Only the eyes and hill openings can be seen in this buried guitarfish; a
better look at the head; beginning to take off to safer ground; swimming away

This document maintained by Dr. Bill Bushing.
Material © 2003 Star Thrower Educational Multimedia