Water flea, Daphnia pulex
Picture published by NPR.org
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A new complete genome has been sequenced and a new surprising fact was unveiled: The new record holder for having the most genes among animals is the very tiny water flea, Daphnia pulex (Crustacea: Branchiopoda: Cladocera). It has approximately a whooping 31,000 genes! (compared to about 23,000 in humans). Their genome, nevertheless, is not too big, which makes the surprise even bigger: It is about 200 million base pairs (compared to the 3 billon in the human genome).
This is another example of how size and morphological complexity are poor predictors of genome size or number of genes (and viceversa). Water fleas are typically no more than a few millimeters long and, to the unaware, rather unremarkable little fellows. However, they are physiologically very complex, and this seems to be the reason for which they have accumulated so many genes over evolutionary time.
Yet another surprise that the growing field of Genomics has given us.
Click here for an extended version of the news on NPR.org.
Click here to access the abstract of the original paper on Science Magazine.
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