Parasitic Isopods of the Ryukyu Islands

Scorpionfish, lionfish and stonefish all belong to the family Scorpaenidae. They all are well camouflaged and highly venomous. Their defensive spines can deliver a painful sting. It’s best to wear exposure protection and maintain good bouncy control to avoid getting envenomated by these ambush predators.

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In the 1980’s Robert Bolland stumbled upon an interesting underwater find. He found a tiny undescribed isopod hitching a ride on a scorpionfish. 1984 the parasitic isopod Renocila bollandi from Okinawa was named after him.

Renocila bollandi from

Over the years I photographed a dozen of these orange Isopods (Renocilla bollandi)

I have always wondered,

  • What is the relationship between the two?
  • Is the relationship mutualism, commensalism, and parasitism?
  • Why does the isopod only prefer venomous fish (scorpionfish) as its host?
  • Why does the isopod always stay close to the eye?

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Scorpionfish Okinawa

Scorpaenopsis diabolus scorpionfish

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See why they call it the bearded scorpionfish (Scorpaenopsis cirrhosa).

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Learn more about the hazardous marine life of Okinawa.

Learn more about Robert Bolland and his research at The Okinawa Slug Site.

 My Mission: To Document and Preserve the Wildlife of the Ryukyu Islands

This site is also designed to help people identify the beautiful animals of Okinawa, basically to serve as an online nature reference guide. If you would like to make a contribution to support my mission, please click on the donation link  paypal.me/maketheswitch4nature

Your donations will help conservation initiatives as well as bring solutions to the worldwide pollution issues on our beautiful shorelines.  Thank you for your support, Shawn M Miller.

#MakeTheSwitch4Nature

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The benefits of changing your colors by Shawn Miller

How cool would it be to have the ability to change colors in a matter of seconds?  In the beautiful waters of Okinawa,  we have a few fish that are capable of changing color quickly.

The Arrow Bulleye (Priacanthus sagittarius) is a stunning dark ruby red when its hiding from predators. It stays close to the coral reef and blends in well.

Red Bigeye ( Pricanthus sagittarius )

Red Bigeye ( Pricanthus sagittarius )

When the Arrow Bullseye is threatened, it flees into open water and changes to a lighter color.

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Red Bigeye ( Pricanthus sagittarius )

It eventually changes to silver in a matter of three seconds

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Red Bigeye ( Pricanthus sagittarius )

Another example of color change happens at the cleaning station. A cleaning station is a designated location where fish come to get their skin, fins, eyes, mouth, teeth, and gills cleaned by cleaner fish. This is an example of Mutilism. The cleaner fish gets fed fresh parasites and the client gets cleaned. All fish swim into the cleaning station and patiently wait to get cleaned.

The blue-lined surgeonfish and rabbitfish (video below) pull into the station and immediately turn dark in color. The purpose of this is so the cleaner fish can spot the parasites easier and speed up the process.

Fish cleaning station

Fish cleaning station

They naturally change back to their lighter color when the exit the cleaning station.

Nice and clean

Check out this rare event in nature, that few will ever see in the wild.

 

Could the increase in tourism contribute to fish disease and parasites? Is it possible the cleaner fish can’t keep up?

Isopods and copepods are bloodsucking parasites commonly found at Maeda point. In the recent years, tourism has increased and some days thousands of snorkelers enter the water. Parasites occur naturally but with the increase in tourism, I believe they are becoming more abundant.

One possible reason is due to guided fish feeding tours. They often feed the marine life large amounts of fu (harvested wheat rolls) and other manmade items. In the past, it was popular to feed the fish processed sausage.  I have been diving Maeda point since 1992. I have observed a decline in healthy coral colonies and other marine life. I have also seen more fish with skin disease and parasites in recent years.  Below are some fish with parasites photographed at Maeda point.

Isopod-  Renocilla bollandi

Isopod- Renocilla bollandi

Rhabdamis sp

Rhabdamis sp

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Filefish with tiny parasites

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Twin spot lionfish and parasites

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Pennantfish and parasite

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Firefish with parasites

Butterfly fish

Butterflyfish and parasites

Infested with parasites

Parasite infestation

Damselfish

Damselfish with parasite

 My Mission: To Document and Preserve the Wildlife of the Ryukyu Islands

This site is also designed to help people identify the beautiful animals of Okinawa, basically to serve as an online nature reference guide. If you would like to make a contribution to support my mission, please click on the donation link  paypal.me/maketheswitch4nature

Your donations will help conservation initiatives as well as bring solutions to the worldwide pollution issues on our beautiful shorelines.  Thank you for your support, Shawn M Miller.

#MakeTheSwitch4Nature