Predation or competition?

This morning I have just written an article on the new 105mm VR and its performance underwater. Anyway I decided to use this shot to show the high level of detail captured by the new lens.

Anyway I have only just realised that the two gobies are different species. The eater is a Spotlight Goby and the eatee is a young Cleaning Goby. And it got me thinking - is this predation or competition?

Alex

I vote predation, competetors usually just beat each other up and let them swim off to die.

Both maybe? Since they are different species, I think the big one is just eating a recruit of its competition. I've never seen two adults of the same Elacatinus species in the same coral head before.

As an update to this thread I thought I'd post a recent picture of some different gobies I snapped in Bali:

Looks to me that a similar thing is happening here. Although I am still not sure what it is!

Alex

And taking this new picture reminded me of one of the shots from earlier in the Caribbean gobies sequence:

Anyway info, guesses and wild speculation encouraged!

Alex

I don't know pacific fish ID but the one on the Bali image resembles Emblemariopsis-type blennies in the Caribbean. If this is a blenny, and I may well be wrong, then it is not a cleaner trying to keep his monopoly of a cleaning station. Of course it can still be trying to defend its territory, but why not eat your opponent if size allows. An interesting question is if this behavior supplies a meaningful part of their diet or if they only do it when Alex is nearby. Their must be stomach-content studies on these little fellas.

Bart

I think the common name is "many-host goby"

Cheers

James

Alex .. you obviously stayed and watched what these guys did .. did they ever kill or eat the smaller one ? what did the smaller one do if it was released ?

the photos almost look like friendly play time to me !

This is very interesting and I'd like to know more expert opinions on this.

I tend to think the gobies are eating the smaller ones as stated earlier (not competition related - as from what I've seen with most of these cleaner gobies competition is not usual as the more gobies in one area the more fish that are attracted to the cleaning station, etc.). But why they would eat the smaller gobies I'm not sure. Possibly the smaller ones didn't grow fast enough before they joined the cleaning station area due to some circumstances; or possibly cleaning business had been so slow that the larger ones were starving?

And I wonder too how much of this actually goes on (or if Mr Mustard is just some sort of a catalyst for this...... ......?)

Looking fwd to more data, Carol (BTW great photos Alex!!) B)

Alex .. you obviously stayed and watched what these guys did .. did they ever kill or eat the smaller one ? what did the smaller one do if it was released ?

Actually I didn't stay and watch either for long as I passed on both subjects to other photographers.

I am pretty sure that the smaller fish were dead in both photos. Maybe the bite over the gill covers is how the larger gobes strike and suffocate their prey? Although then I am surprised that in the first picture the goby tried to eat the smaller one backwards, when it was already dead.

I tend to agree with Carol that if they are eating them then it is unlikely to be competition driven. Next time I see it going on I will hang around and watch for developments.

Alex

I don't think so, even though it is good to have many gobies to attract more fish, it is bad to have to share resources with other species. And in both instances the fish are from different species, that's why I think it is competition. Next time you see a cleaning station, take a look, all fish are going to be of the same species, and usually several sizes.

Luiz

I did a quick search for info on these gobies using the genus name and words like "diet" "feeding" "competition". The cleaners don't seem to eat fish - gut analysis shows they're feeding on the ectoparasites they take off the fish, small worms & crustaceans, bits of the sponges or corals they live on, etc. They are very territorial towards other species and occasionally towards other members of the same species if they're in different age groups. I'd go with competition.

I did a quick search for info on these gobies using the genus name and words like "diet" "feeding" "competition". The cleaners don't seem to eat fish - gut analysis shows they're feeding on the ectoparasites they take off the fish, small worms & crustaceans, bits of the sponges or corals they live on, etc. They are very territorial towards other species and occasionally towards other members of the same species if they're in different age groups. I'd go with competition.

I think you are correct Leslie, but consider this if they are feeding off ectoparasites, etc and there are not enought fish visiting the cleaning station they could in theory be "starving" and feeding off organisms on the smaller gobies (and possibly killing them in the process); or changing their diets and eating the smaller gobies themselves?

I've never seen this "eating" behavior Alex has captured but I'll for sure be on the lookout now!!! We should all be!

Very interesting, thanks again Alex!

Best, Carol

PS I want to add though I'm not assuming all these are "cleaner" gobies, in fact we know that the spotlight goby (lg one in Alex first pic) doesn't clean much if at all and the little cleaning or sharknose goby in that same pic that is being "eaten" is a cleaner goby. Is this just non-cleaner gobies eating less-aggressive cleaner gobies? Maybe it is what they do?

The other gobies from Bali - I'm not familiar with their behavior but some could act as cleaners.

I think this is predation for whatever reason. As it seems to me now like the more likely "non-cleaning" or "less-likely-to-clean" gobies are doing the "eating".

Again I've observed a lot of small gobies around Florida and the Caribbean and I've never witnessed any of these type gobies eating goby........ Either it goes on and I never caught it or this is happening in areas where something is out of balance.

But again Leslie leans towards competion........?

Just more ?s C