Mustangs and Sunbursts are merely different color morphs of the same species – be Lined Seahorse (Hippocampus erectus) – and they therefore differ primarily in the coloration they express. As such, they are equally hardy and adaptable, have the same aquarium requirements, and, of course, they make ideal tankmates for one another. They will even interbreed freely, so you may certainly get one of each (a single Sunburst and a single Mustang) – or a pair of each – and keep them together in the same aquarium with no problems whatsoever.
So the short answer to your question is that Mustangs and Sunbursts are two different strains of Hippocampus erectus seahorses that have been selectively bred by Ocean Rider for dozens of generations to bring out different colors, and which have now become highly domesticated and very hardy aquarium specimens.
For more in-depth answer, let’s get back to the differences between the Mustangs and Sunbursts and go over that in a little more detail, Lucienne, since that is something that is confusing for many hobbyists. As I said, they are the same species, and therefore share identical aquarium requirements, with the primary difference between the two being the color that they express.
The difference in the coloration that the Mustangs and Sunbursts are most likely to display is due to differential proliferation of chromatophores cell types. In a nutshell, Mustangs have a preponderance of black pigment cells (melanophores) and less pigment cells for bright coloration than the Sunbursts. On the other hand, the Sunbursts have fewer melanophores or black pigment cells, and more yellow pigment cells and red pigment cells proportionally than the Mustangs do. As a result, the Mustangs are more likely to display a dark brown or gray or black color pattern than the Sunbursts, and the Sunbursts are more likely to display the sunset colors (shades of yellow, gold, peach, orange, and amber) at any given time than Mustangs.
And, in turn, the reason that Mustangs and Sunbursts have a different proportion of the various chromatophores is because of their breeding or ancestry. To put it most simply, Sunbursts have more brightly colored seahorses in their particular family tree. A Sunbursts’ parents and grandparents and so forth going back for many generations were brightly colored seahorses. As a result, the latest generation of Sunbursts has relatively few melanophores and more colorful pigment cells than Mustangs.
The Mustangs, on the other hand, have had ancestors (parents, grandparents, great grandparents, great-great grandparents, etc.) going back many generations that have had the dominant dark brown or black lined color pattern that is typical of wild Hippocampus erectus. As a result, the Mustangs have more black pigment cells or melanophores then Sunburst do, and proportionally fewer of the yellow pigment cells or red pigment cells then Sunbursts.
In other words, because of the coloration of their ancestors going back many generations, Mustangs and Sunbursts now differ genetically in that their genes for coloration have been altered by selective breeding. In short, the genotype of Sunbursts and Mustangs differs when it comes to their coloration, as determined by the number and type of different chromatophores they each carry.
Although they are the same species, because of their differing genealogy due to selective breeding, Mustangs and Sunbursts now have distinct genotypes, and the Mustangs are much more likely to be dark colored at any given time, whereas the Sunbursts are more likely to be brightly colored at any given time.
In other words, Lucienne, the difference between Sunbursts and Mustangs is all in the genes. But since you cannot see the genes and can only judge a pony by its stripes – i.e., by the color it expresses at any given time – Mustangs and Sunbursts may sometimes appear to be the same outwardly. Under some circumstances, both types may display the same phenotype or coloration.
That’s why it is a bad idea to display Sunbursts under high-intensity lighting such as metal halides, Lucienne. The high intensity lighting stimulates the production of excess melanin in the skin of the seahorses (in order to protect them against UV radiation associated with bright light), and they will turn dark brown or black as a result. (It doesn’t matter how many bright yellow or orange pigment cells they may have underneath because they are hidden when the melanophores are expanded and the pony looks black or dark brown regardless.)
And that’s why it’s good to have lots and lots of brightly colored hitching posts and pretty artificial corals for your ponies, which will encourage them to look their best and brightest. In such a tank, the Sunbursts will retain their true glory and even Mustangs may suppress their melanophores or black pigment cells and show attractive colors or go through different color phases to better blend into their background or to better match their favorite hitching post.
As you know, Lucienne, when it comes to their color pattern, seahorses are not like most other marine fish — rather, they are truly the chameleons of the sea with a propensity for changing color in response to a wide range of environmental factors, hormonal influences, and behavioral interactions. But with the right genotype and the right aquascaping or aquarium decor, the aquarist can turn this proclivity to his advantage and encourage his seahorses to be brightly colored at all times.
Of course, there are always exceptions. There are times when a Mustang may take a liking to a particularly colorful hitching post and brighten up in response, and there are times when he Sunburst may darken in coloration if it is stressed or subjected to unfavorable conditions. But when a Mustang adopts brighter coloration, it is relatively uncommon – exceptional, whereas when he Sunburst displays bright yellow or orange coloration is the norm – the rule, for that strain of Hippocampus erectus.
In short, Lucienne, if one of your main interests is in having brightly colored seahorses, then Sunbursts are your best bet and can tip the odds in your favor, whereas if you’re not concerned about the coloration of your seahorses, then the darker Mustangs are a better bargain and hard to beat in terms of their personality, hardiness, and adaptability.
If you contact me via e-mail, Lucienne, I will send you a document as an attachment to my reply that discusses the differences between Mustangs and Sunbursts in much more detail than I can go into in this brief message, and it also includes extensive photo galleries of both Mustangs and Sunbursts to give you a better idea of the different colors each of these types is likely to express. As you will see from these portrait galleries (all of which were taken by their proud owners in their home aquariums), it is actually very easy to tell which of the ponies are Mustangs and which are the Sunbursts – renowned for their pretty colors among home aquarist – simply by observing their coloration and pattern. You can download the attachment and save it on your computer for future reference, and it should give you an excellent idea of exactly what the Mustangs and Sunbursts are like so you can make an informed decision when you place an order.
You can always reach me at the following e-mail address:
Best wishes with all your fishes, Lucienne!
Pete Giwojna, Ocean Rider Tech Support