Why are juvenile angelfish so similar?

[JHawlz9989]

Been searching for a bit, and I can't find a good reason as to why juvenile angelfish all have such similar colors and markings. It seems most have some variation of a dark body with blue/white stripes. Why is this?

Josh

 

[komori]

My guess is that it is a defense mechanism, and that where those fish are found in the wild the markings will be beneficial for hiding them

Komori

 

[reret10]

huh well once in the great barrier reef I saw a bunch of angelfish and they were blue and yellow I think but they may have been blue and white it was a bunch of years ago

 

[Recty]

Well, a little fish doesnt want to look edible and be super flamboyant and easy to notice. Dark colors and stripes help them blend in with corals/seaweed and hide better.

It's all about staying alive, and dark with stripes seems to work really well.

 

[Kahuna Tuna]

The color change is a survival thing, as the juvies are so much more vulnerable than the adults to predation and I have often found that juvies from the same genus often look alike in both angelfish and other fish families. If you have ever seen juvie Pomacanthus angels in the wild you will notice they are very reef attached and rarely venture into open water, the dark body with stripes is a very effective camo in this environment. As angels grow they can afford to become more conspicuous and adults are not nearly as reef bound as juvies.

 

[small alien]

In addition to what was put forth above, perhaps they share a common ancestor with roughly those markings, even as an adult. Gradually, they differentiated and found advantage in more flamboyant coloration, perhaps to attract mates. One possibility.

 

[Kahuna Tuna]

Gradually, they differentiated and found advantage in more flamboyant coloration, perhaps to attract mates. One possibility.

I think there is something to this, Pomacanthus angels are also one of those genus that seems to hybridize more commonly than many others.

 

[Wolverine]

In addition to what was put forth above, perhaps they share a common ancestor with roughly those markings, even as an adult. Gradually, they differentiated and found advantage in more flamboyant coloration, perhaps to attract mates. One possibility.

That I think is the big key. The further back in the life cycle you go, the harder it is to distinguish animals (works with all animals, not just fish). If it's a topic you're interested in (directed at anyone in the thread), look up some of Stephen Jay Gould's discussion of ontogeny.

 

[alton]

What about the fact they are cleaners on the reef? My baby chrysurus does a bang up job on my regal.

 

[spieszak]

nothing to back it up, just "supposing" here... but fish love to eat baby fish... its possible the coloration your noting is of a "common" fish that guarded their young.... Looking like a fish that has aggressively protective parent(s) is almost as good as having aggressively protective parent(s)...

 

[small alien]

What about the fact they are cleaners on the reef? My baby chrysurus does a bang up job on my regal.

Great thought.

 

[small alien]

To the OP, great question. I wish we had more "conceptual" threads like this on RC.

 

[philter4]

I think there is something to this, Pomacanthus angels are also one of those genus that seems to hybridize more commonly than many others.

Actually the most common hybrids are between Holacanthus rather then Pomacantus.

There is a combination of reasons that juvenile angels are colored so similarly to each other, and so differently from the adults. Angels are very territorial, if the juv's were the same as the adults they would probably not survive on the reef because the adults would chase them out of their territories. This would not only push them to areas where the habitat isn't the best, which for a young fish would mean less and lower quality food, poor hiding places, and higher incidence of predators. As a different color pattern the adults will usually tolerate a young fish in the same area and it gives the young a chance to establish it's own territory and grow up.

As far as why they are so similar to each other here are some of the reasons I think are the best answers to your question:
They are all related and as mentioned maybe even a single common ancestor, so the patterns are going to be close. If you look at different genera, the color pattern and combination of color and patterns is different from each genus but similar within the genus.

Many are cleaners which affords them some protection, the color pattern is repeated in many cleaning fish, black and blue or white is found on cleaner wrasses and neon gobies just to name a few. Here in the Atlantic there is are several yellow and black cleaner gobies and the baby french, grey and rock beauty all have that same color pattern.

They also mimic the color pattern of cleaners even if they don't actually clean themselves, not all juvenile angels will pick parasites but kpredators are so used to not eating fish with cleaning colors that they don't even try.

The color pattern is very easily lost on the reef. Both the brightness and stripes (think of zebra on land) tend to confuse the predators and with all of the holes and tunnels in the reef rock, just a fraction of a second may mean the difference between getting away and being eaten.