DIVE DRY WITH DR. BILL #734: GENTLE GIANTS NEED A CLOSE SHAVE
My friends the gentle giants, also known as giant sea bass (Stereolepis gigas), often look like they could use a close shave. They remind me of the stubble that grew profusely on my chinny chin chin as I lay in the hospital last summer. But I'm a mammal and we're known for growing hair. Giant sea bass are fish, specifically wreckfish, and hair is not one of their characteristics.
The "stubble" that one sees on the GSBs comes from another life form that attaches to them. They are parasitic copepods, also known as sea lice. Fish expert Dr. Milton Love suggested to me years ago that they belonged to the copepod genera Caligus or Lepeophtheirus. Later, during my research for a revised version of my Gentle Giants DVD, I found that Hobson identified them as Lepeophtheirus longipes. Although very numerous, at least on GSBs, they have no specific common name so sea lice will have to do.
Now species of copepod parasites infest many species of fish. I have seen them on sheephead and kelp bass in our waters. These are much smaller than the ones on the giant sea bass and are a good test of my vision. Most of these parasites derive their nourishment from the host's tissues, fluids or blood.
Parasite infections are most easily transmitted from one fish to another while they are in large aggregations. For example, pen-raised salmon and other fish allow for easy transfer of parasites from one fish to another. Wild salmon approaching too close to the pens may also become infected. This is one reason salmon farming has been banned in some areas such as Alaska.
When the gentle giants gather in our warm, shallow waters during spring, summer and fall to mate; they come into close contact with one another. I have seen young GSBs with very few or no parasites mixed in with much older individuals which are heavily infested. Undoubtedly the younguns get infected by their elders. This is the reverse of when my granddaughters come home with colds and poor Papa Bill gets sick.
No shaver or blade can remove these parasites from the giant sea bass like my electric razor did to my stubble this morning. And to the best of my knowledge, our famous local barber Lolo doesn't make house calls to Davy Jones' Locker.
Fortunately other fish perform this function for the gentle giants. I most often see young sheephead, rock wrasse and señoritas picking parasites off the body of the gentle giants as they hover midwater. Wrassses like these, with their pointed jaw and forward directed teeth, make excellent cleaner fish both here and throughout the warmer waters of the world. I occasionally see kelp bass doing this and there are reports that small island kelpfish, juvenile giant kelpfish and even blue-banded gobies perform this function off the northern Channel Islands.
These cleaner fish would make a tasty snack for the giants were they to come too close to the mouth and get sucked in. Therefore the smart ones focus on the parasites along the dorsal surface, side and belly and largely leave the head region alone. This explains why the heaviest parasite loads are around the anterior end of the body. On occasion I have seen a brave (or stupid?) kelp bass dive down and pluck a parasite from the head, but they very quickly do a 180 and bounce away!
The white "hairs" we observe extending from the body of the parasitic sea lice are actually clusters of eggs on the female. Carried thus, they are well oxygenated allowing rapid development. The eggs hatch into planktonic larvae which obtain their food the old fashioned way by chowing down on their fellow drifters. The late larval stage settles onto fish but do little damage until they mature and adopt their nasty parasitic ways. I've even seen some of these copepods appear to bore into the GSBs eye. Maybe that also explains my poor vision?
© 2017 Dr. Bill Bushing. For the entire archived set of over 700 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: Giant sea bass heads with parasitic copepods; close-up of the parasites and male rock wrasse safely picking parasites off a GSBs flank.
My friends the gentle giants, also known as giant sea bass (Stereolepis gigas), often look like they could use a close shave. They remind me of the stubble that grew profusely on my chinny chin chin as I lay in the hospital last summer. But I'm a mammal and we're known for growing hair. Giant sea bass are fish, specifically wreckfish, and hair is not one of their characteristics.
The "stubble" that one sees on the GSBs comes from another life form that attaches to them. They are parasitic copepods, also known as sea lice. Fish expert Dr. Milton Love suggested to me years ago that they belonged to the copepod genera Caligus or Lepeophtheirus. Later, during my research for a revised version of my Gentle Giants DVD, I found that Hobson identified them as Lepeophtheirus longipes. Although very numerous, at least on GSBs, they have no specific common name so sea lice will have to do.
Now species of copepod parasites infest many species of fish. I have seen them on sheephead and kelp bass in our waters. These are much smaller than the ones on the giant sea bass and are a good test of my vision. Most of these parasites derive their nourishment from the host's tissues, fluids or blood.
Parasite infections are most easily transmitted from one fish to another while they are in large aggregations. For example, pen-raised salmon and other fish allow for easy transfer of parasites from one fish to another. Wild salmon approaching too close to the pens may also become infected. This is one reason salmon farming has been banned in some areas such as Alaska.
When the gentle giants gather in our warm, shallow waters during spring, summer and fall to mate; they come into close contact with one another. I have seen young GSBs with very few or no parasites mixed in with much older individuals which are heavily infested. Undoubtedly the younguns get infected by their elders. This is the reverse of when my granddaughters come home with colds and poor Papa Bill gets sick.
No shaver or blade can remove these parasites from the giant sea bass like my electric razor did to my stubble this morning. And to the best of my knowledge, our famous local barber Lolo doesn't make house calls to Davy Jones' Locker.
Fortunately other fish perform this function for the gentle giants. I most often see young sheephead, rock wrasse and señoritas picking parasites off the body of the gentle giants as they hover midwater. Wrassses like these, with their pointed jaw and forward directed teeth, make excellent cleaner fish both here and throughout the warmer waters of the world. I occasionally see kelp bass doing this and there are reports that small island kelpfish, juvenile giant kelpfish and even blue-banded gobies perform this function off the northern Channel Islands.
These cleaner fish would make a tasty snack for the giants were they to come too close to the mouth and get sucked in. Therefore the smart ones focus on the parasites along the dorsal surface, side and belly and largely leave the head region alone. This explains why the heaviest parasite loads are around the anterior end of the body. On occasion I have seen a brave (or stupid?) kelp bass dive down and pluck a parasite from the head, but they very quickly do a 180 and bounce away!
The white "hairs" we observe extending from the body of the parasitic sea lice are actually clusters of eggs on the female. Carried thus, they are well oxygenated allowing rapid development. The eggs hatch into planktonic larvae which obtain their food the old fashioned way by chowing down on their fellow drifters. The late larval stage settles onto fish but do little damage until they mature and adopt their nasty parasitic ways. I've even seen some of these copepods appear to bore into the GSBs eye. Maybe that also explains my poor vision?
© 2017 Dr. Bill Bushing. For the entire archived set of over 700 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: Giant sea bass heads with parasitic copepods; close-up of the parasites and male rock wrasse safely picking parasites off a GSBs flank.
