Dive Dry with Dr. Bill

#274: Pilotfish

I've spent the last four months working on what I hope will be my magnus opus (Latin for "great work," the most renowned achievement of someone): more than 2 1/2 hours of footage about the Sharks and Rays of Southern California, divided into seven 22-minute episodes. My hope is that this will be the start of a commercial cable TV series on the marine life of southern California. After nearly eight years without a "celery" (you know, paycheck), it's about time I actually make some money.

My work on this series has led me to realize that one species I've never written about in these columns is the pilotfish that may be seen accompanying sharks. This member of the jack family is uncommon in our waters, and rare north to Vancouver Island, so it is not often observed by divers here. In fact, the only time I've seen them is on the shark dives SCUBA Luv puts together out in mid-Channel. The pilotfish is far more common in tropical to warm temperate waters such as the Gulf of California and south to Peru and the Galapagos in our hemisphere. They tend to be found in the upper 100 feet of the water column, although some report they may be seen down to nearly 500 feet.

The pilotfish has fairly unique markings. Five to seven dark bars or bands are very obvious on the silvery white to grayish body. It is said that when they get excited, perhaps upon meeting a lady pilotfish, the dark bars disappear and they turn silvery-white with three broad blue patches appearing on their back. These jacks are usually 6 to 15 inches in length, but may reach up to two feet. Their tail is forked and also has dark bands on it.

Pilotfish are commonly associated with sharks. However, they will also follow rays, billfish, turtles, whales and even ships on occasion. It is said "the ancients" (not to be confused with me and my peers, we're just the geezers!) believed they would guide ships on their desired course. The Greeks actually held them to be sacred. Too bad there weren't a few pilotfish to guide the Exxon Valdez out of Prince William Sound, Alaska, years ago. Of course those waters are well outside their normal distribution range. The young pilotfish are known to follow drifting seaweeds and jellyfish, which are slow enough for them to keep up with.

The relationship between sharks and pilotfish is one of mutual benefit. The pilotfish feeds by picking parasites off the shark's body, as well as munching on the leftovers from a shark's meal. In turn, the pilotfish receives protection from predators by staying close to the shark. There are reports of younger pilotfish swimming into the mouths of sharks to clean food particles from between their teeth. I'd prefer to go to Dr. Calise instead! Pilotfish will also eat drifting invertebrates and pelagic (open water) fish.

Pilotfish should not be confused with another group of fish that are associated with sharks, the "shark sucker" or remora. These fish have a greatly modified first dorsal fin that serves as a sucker, allowing them to attach to sharks and other marine life. By attaching to sharks, remoras also gain protection from predators as well as very energy efficient transport. There is some debate as to whether remoras benefit their shark hosts or not. Some feel the remora's diet is primarily shark leftovers and feces. Remind me to never accept a dinner invitation from a shark sucker! Others feel the remora may actually feed on parasites and bacteria, thus helping the shark. If true, I'm still not interested in a dinner "date" with one! Speaking of which, no diving for me this weekend... I have another date with the lovely Tifo!

© 2008 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 and on Charter Communications Cable channel 33 at 7:30 PM on Tuesdays in the Riverside/Norco area. 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," "Common Fish and Invertebrates of the Sea of Cortez" or the new "Sharks and Rays of Southern California" DVD's. Yes, take Dr. Bill home with you... we'll both be glad you did!

Pilotfish accompanying blue shark in mid-Channel off Catalina; remora after releasing
from Nassau grouper down in Belize.

This document maintained by Dr. Bill Bushing.
Material and images © 2008 Star Thrower Educational Multimedia