Dive Dry with Dr. Bill

#253: Shovelnose Guitarfish

It has been more than four years since I last wrote about the shovelnose guitarfish. One reason is that I rarely see them any more. I encountered one on my very first dive the day I moved to Catalina from Boston on August 24, 1969. I had arrived off Arrow Point aboard the Golden Doubloon, one of the early dive boats in southern California. As I descended towards the bottom just outside the kelp forest, one of these shark relatives swam right past me. I remember that first salt water dive very well considering it was the 60's... and I was there!

On my recent dives off La Jolla with Missy, she and her family encountered a group of several dozen shovelnose guitarfish in shallow water over the sandy bottom at the Marine Room dive site. I missed seeing them since I was focused on filming leopard sharks nearby. It made me think about this species... and why I so rarely see them in our waters when they are fairly common on the mainland. Of course one reason is that I am a kelp forest ecologist, and kelp grows in areas with rocky substrate rather than sandy bottoms. You wouldn't look for a woolly mammoth in a tropical rain forest... but then since they are extinct, you shouldn't be looking for them anyway! However, my deep diving in recent years frequently places me over sandy and silty bottoms and I've only seen one at such depths. Although these rays may be found as deep as 300 feet, they are usually seen in water shallower than 40 feet.

Shovelnose guitarfish are found from central California to the Gulf of California (Sea of Cortez), Mexico. Our neighbors to the south refer to them as Pez guitarra or pez diablo. In certain areas of Mexico they are dried and sold as souvenirs that look like a devil. These fish are truly one of the more unusual characters encountered underwater. Shovelnose guitarfish are known from fossils dating back 100 million years, so many of our evolutionary ancestors probably marveled at them, too. Their remains are somewhat common in Native American middens, indicating they were a food source for these early "Californians."

Guitarfishes are rays, not sharks although both groups are classified together as cartilaginous fish because they lack the hard, calcium carbonate bones of more commonly encountered bony fishes. 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.

This species may reach 5 1/2 feet in length and 40 pounds. Its long, pointed snout distinguishes it from other members of the guitarfish family in southern California waters. These include the banded guitarfish which is rare in our region (I've never seen one), and the thornback ray which is common on the mainland but I've only seen it once off Catalina.

The guitarfish pictured with this article was free swimming as it passed before me in the waters off Sea Fan Grotto, just like the first one I saw back in 1969. However, these rays spend most of their time resting on the bottom, often buried in the sand. It is said that they can change colors to match their surroundings. This camouflages the fish, allowing them to ambush unwary prey that comes too close. Here they feed on animals that live on or in the sand including fish, crabs, shrimps and worms. Guitarfish have been observed feeding on sand crabs in waters just a few inches deep. Guitarfish were formerly considered undesirable by-catch by commercial fishermen, but are now the target of a minor fishery. The flesh on their tails and backs is considered good tasting.

They sometimes are found in large groups, usually when they're "in the mood." 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.

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 ones I've encountered were all solitary. After giving me a fairly brief opportunity to film them, they all bolted, swimming away at a fast pace. They were probably in search of a mate. Not a bad idea! I've been trying to locate a "mermaid" of my own species for years.

NOTE: The Weather Channel will broadcast a 30-minute show on Catalina as part of its Weather Ventures series. This show features some of my underwater footage and a brief interview with me and dive buddy Heather Martonik, as well as other island residents including Ron Moore and Fred Freeman. It can be seen on October 12th or October 16th at either 4:30 or 8:30 PM PDT.

© 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!

Images of the free-swimming shovelnose guitarfish filmed off Sea Fan Grotto last year.

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