Behold the bristlemouth, the most common vertebrate(?)

[DavidBrown]

Recently I learned about a small fish called the bristlemouth. They have bioluminescent spots on their bodies, are about 3 inches long, and may be the most common vertebrate on Earth. Scientists estimate that there may be quadrillions of them. In contrast there are only 24 billion chickens and under 8 billion humans.

Has anybody here ever seen a bristemouth? Are there any in aquariums? It seems like it would make a potentially interesting exhibit to say that one displays the most common vertebrate on Earth - and that almost nobody has seen the species.


https://www.nytimes.com/2015/06/30/science/bristlemouth-ocean-deep-sea-cyclothone.html?_r=0

 

[Chlidonias]

I've never seen a live one but I've seen heaps of dead ones. The containers of dried fish sold commercially as turtle food seem to be mostly small marine fish and shrimps, and contain lots of the deeper-water species like bristlemouths. Presumably they are trawled at night when they rise in the water column.

 

[temp]

1) They've never been kept alive for a longer period in a captivity and that is unlikely to change anytime soon, as they tend to live at great depths (very difficult to bring to the surface alive), are small (even harder to bring to the surface than medium-sized fish), are open-water species (hard to catch by gentle non-trawling methods and harder to keep alive, even among species of shallower waters) and based on the little knowledge available they are highly photophobic (show a strong dislike for even the smallest amount if light). There are several other groups such as the marine hatchetfish and lanternfish that in these perspectives can be compared to the bristlemouths, and they're bioluminescent, numerous and follow the diel migration too. I've often wished for an exhibit with one of these groups as it has the potential to be both interesting and educational, but I doubt I'll ever see one alive, disregarding videos taken in the deep sea. Same with the numerous golomyankas of Lake Baikal, the deepest living freshwater fish in the world, which in general behavior (except for their strange breeding behavior) are more like deep-water marine fish than freshwater fish.

2) It's somewhat misleading to call the bristlemouths the "most common". Although several of the individual species undoubtedly are very common, the "commonest" claim covers entire genera (as opposed to the chicken claim –one species– in the NYT article). I'm sure that if you put together e.g. the most numerous clupeid genera you'd end up with huge numbers too. The same can be said of other groups. Additionally, species-level taxonomy among the bristlemouths is largely based on studies that are several decades old. In all probability, the true species diversity is strongly underestimated, similar to that seen in many deep-ocean genera, meaning that the high population number in all probability has to be divided among even more species than it is today.

 

[DavidBrown]

Thanks for the details, Temp. It sounds like this is a fascinating group of fish that needs much more investigation on all fronts.