"Shadowing" any help?

[PeaceDog]

While in Saba this past february, I had the opportunity to witness an incredible display of cooperative feeding known as "shadowing," or "nuclear feeding" as it is sometimes called.

Essentially what happens is several groupers or wrasses follow behind some form of eel while the eel goes into crevices and holes that a regular fish couldn't squeeze into. When an eel pulls something out, usually they share whatever it is.

Does anyone know any more about this behavior? I'd like to describe it for a video I'm making, and I'd like to be scientifically correct. Possibly some of you could direct me to articles or web sites that can further flesh this out for me.

If anyone would like to see video of the amazing incident, please let me know and I can send you some.

 

[Pettifogger]

While in Saba this past february, I had the opportunity to witness an incredible display of cooperative feeding known as "shadowing," or "nuclear feeding" as it is sometimes called.

Essentially what happens is several groupers or wrasses follow behind some form of eel while the eel goes into crevices and holes that a regular fish couldn't squeeze into. When an eel pulls something out, usually they share whatever it is.

Does anyone know any more about this behavior? I'd like to describe it for a video I'm making, and I'd like to be scientifically correct. Possibly some of you could direct me to articles or web sites that can further flesh this out for me.

If anyone would like to see video of the amazing incident, please let me know and I can send you some.

I don't know what it is called off-hand, but a similar situation happens happens with trumpetfish... They follow along, right behind another bigger fish. Other little fish see the big one, swim away and the trumpetfish, which seems to be looking a little behind, gets em when they come back out just as the bigger fish passes... Kinda neat to watch.

 

[Charlie99]

"Reef Fish Behavior" book by Ned Deloach (photos by Paul Humann, and part of the popular Paul Humann Fish ID series) discusses shadow feeding / nuclear hunting / hunting confederations of eels and groupers.

I was lucky enough to see a hunting party quite similar to your experience. It was a Goldentail Moray accompanied by 5 or 6 reddish, spotted, groupers (I wrote "Rock Hind" in my log, but they might have been Graysby). Cozumel's Villa Blanca Dropoff, 14Jan 03, overcast, 80F water, about 1.5kt current.

The Rock Hinds would cluster around the sides of a small patch coral head while the eel went inside. After the eel came out, it would pause until a couple groupers came up near it, then it would dash over to another coral head. It would pause a couple of seconds to let the groupers position themselves before entering the coral head.

I watched the hunting group cycle through 3 or 4 coral heads without success, and would have hung around for a lot longer but the current had pulled the rest of the Scuba Club Cozumel dive group on out of sight and I reluctantly rejoined them.

This experience prompted me to buy an underwater camera. Luckily, I had it with me when 3 humpback whales swam by me in Maui this March!

 

[JRO]

This experience prompted me to buy an underwater camera. Luckily, I had it with me when 3 humpback whales swam by me in Maui this March!

I just checked out those shots in the gallery, I'm glad you had it to!

 

[drbill]

Charlie99's suggestion of the Reef Fish Behavior book is a good one. "Shadowing" occurs in a number of different fish species. Often the fish doing the shadowing is using the other fish to (1) scare potential food up into the water column or (2) simply as a hiding place from which the shadowing fish can dart out after unsuspecting prey. I often see bar jacks shadowing a wide range of fish including hogfish, Spanish hogfish and queen triggers.

Another interesting type of shadowing can be ilustrated with the bar jacks shadowing queen triggers. Queen triggers feed on invertebrates rather than fish. Therefore their presence does not usually threaten or scare away other fish. The bar jack is a piscivorous (fish eating) species and will use the queen trigger to hide behind, then dart out after unsuspecting fish prey.

Dr. Bill

 

[archman]

Nobody's mentioned that bar jacks tend to change colour when they're shadowing. They (rather quickly) change to a deep black colour, resembling an uh, shadow! They're also rather selfish when they're exhibiting this behaviour, and will chase off other fishes from the "host".

I'm not aware of other fish species changing colour, but I rarely get the opportunity to observe it. Anybody want to pipe in on this?

 

[rcohn]

Nobody's mentioned that bar jacks tend to change colour when they're shadowing. They (rather quickly) change to a deep black colour, resembling an uh, shadow! They're also rather selfish when they're exhibiting this behaviour, and will chase off other fishes from the "host".

I'm not aware of other fish species changing colour, but I rarely get the opportunity to observe it. Anybody want to pipe in on this?

I saw a bar jack and an undentified jack shadowing a stingray as it swam back and forth over the sand at Saba. The bar jack retained its normal color.

Ralph

 

[Charlie99]

Nobody's mentioned that bar jacks tend to change colour when they're shadowing.

I'm not aware of other fish species changing colour, but I rarely get the opportunity to observe it. Anybody want to pipe in on this?

Many (most?) species have the ability to rapidly change color.

For me a lot of the attraction of scuba is the amazing complexity of the underwater environment. Only once I learned to recognize most fish and the most common behaviors was I able to start seeing some of the more subtle things. And for everything I figure out, it seems like there are 2 more questions the come up!

Color changes are very common --- territorial/agression displays, mating displays, night colors vs. day colors, color changes to match the surrounds to either better hide or to be able to sneak up on prey.

In Cozumel, another very easy to spot color variation is the egg-guarding colors of Sergeant Majors. The white background color darkens to purple when they are guarding their egg patches. Often, the colors will go even more vivid just before they attack you as you approach the egg patch.

Charlie

 

[H2Andy]

I'm not aware of other fish species changing colour, but I rarely get the opportunity to observe it. Anybody want to pipe in on this?

i assume you mean "while shadowing," as fish change color all the time... and no, i don't know...