Dive Dry with Dr. Bill

#714: The Sharksucker Family

I remember way back to my thrilling summers at Boy Scout Camp Ma-Ka-Ja-Wan in Antigo, Wisconsin. It was a long bus ride up there from the Chicago suburbs, but it meant a week or two of enjoying the natural history of the region. Well, there were two species I didn't entirely enjoy. One was the porcupine, but I only got a few quills stuck in my skin. The other was the bloody leeches that would attach to my body while swimming in the lake or wading in the stream.

Although leeches were used for primitive medical treatment in centuries gone by, I don't know of many people who enjoy these suckers. Fortunately although they poked and prodded me, none of my attending physicians ever threatened me with a leech! As a marine biologist I am lucky since they primarily frequent freshwater habitats. You're probably asking what leeches have to do with the marine environment.

Well, a fish I've encountered in many dive sites around the world reminds me a bit of leeches. I'm speaking of the remora, aka "sharksucker." While these fish do not actually suck the blood of the sharks, rays, large fish, whales, turtles and other critters they attach to, they do have a "sucker" disk created by a modification of the forward dorsal fin.

The sucker disk's morphology is interesting. If the remora moves backwards, the suction increases and it holds fast. Some cultures have actually used remoras to capture turtles due to their strong suction. However, if the remora moves forward, the suction decreases and it may leave the host.

Remoras, sharksuckers and other members of the family Echeneidae are generally found only in tropical and subtropical waters although they may occasionally be seen in temperate waters as well. They live in the open ocean but can also be seen in coastal waters, especially around islands.

In ancient Greece and Rome the remora was believed to be capable of stopping a ship from sailing. The historian Pliny the Elder believed remoras were responsible for the defeat of Mark Antony, famed Roman general and Cleopatra's lover, in the Battle of Actium. He and Cleopatra fled to Greece where they committed suicide. And all this time I thought it was loose lips that sunk ships. Hmmm... perhaps Cleopatra herself caused the defeat.

Remoras and their hosts form a commensal relationship in which both benefit. Although the remora feeds on food scraps, small critters in the surrounding water and even the host's feces (blech), they also remove dead skin tissue and feed on the host's parasites. Of course the poor host has to exert a bit more energy to drag the little sucker around with it!

I've run into several species of remora in my dive travels. Down in the Bahamas a few years ago I filmed the species Remora remora, known commonly as remora, while attached to a turtle host. It has a uniform tan to brown to brownish black color with speckling. Other than that there are no distinctive markings. This species can be found worldwide in warmer waters.

Another species was the slender suckerfish (Echeneis naucrates) filmed two years ago in Palau. We'd often see them attached to some of the many sharks in those waters. I was quite amused when one of them attempted to try a different host.. one of the divers in our group! Probably not enough parasites to suit the sharksucker's tastes!

© 2016 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 29, 10:00 AM weekdays and on Charter Communications Cable channel 33 at 7:30 PM on Tuesdays in the Riverside/Norco area. You can also watch these episodes in iPod format on YouTube through my channel there (drbillbushing). Please help me climb out of self-imposed poverty... buy my DVD's (see this link). Yes, take Dr. Bill home with you... we'll both be glad you did!

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Slender suckerfish in the waters of Palau and common remora attached to a turtle in Bahamian waters.

This document maintained by Dr. Bill Bushing.
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