Sunday, March 25, 2012

Animal of the week: The Dracula fish (Danionella dracula)

No this is not, as you might think from its name, a fish from recent TV-series and movies such as True blood or Twilight that spends its days by sucking blood, having complicated relationship dramas and fighting werewolves. No this is a amazingly tiny cyprinid found in freshwaters of Burma with relatively massive fangs. I write relatively since this is a really tiny fish, so there is no need to panic if you encounter one of these river monsters reaching 17mm in total length. 

The funny thing with the Dracula fish is not surprisingly their fangs. Actually teethes were lost early in the cyprinid lineage and one would then be surprised to discover fangs in a cyprinid. The thing is, the fangs of these fish are not actually true teeth. The teeth of the dracula fish have actually evolved from the jawbones. This is a sexually dimorphic feature so female fish have less prominent fangs. Another interesting thing with this fish, as I learned last year at a cyprinid seminar arranged by the Swedish part of FishBase, is that most of its "bone" in its body hasn't been ossified but is still cartilage. It seems as if the tininess of this species is due to them being sort of neotenic. This means that they become sexually mature earlier when they still are developing, and that they now never grow up so to say. Actually it seems as if their developmental status, as adults, corresponds to a stage in the early life of small sub adult zebrafish of a similar size as the adult dracula fish. Zebrafish, another cyrprinid, is actually a rather close relative of the dracula fish. 

So to summarize, if you ever meet a dracula fish don't be afraid unless you are a tiny crustacean larva swimming around in the rivers of Burma. If you happen to be just one of those crustaceans, be afraid, be very afraid...

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