(Image: The humble water flea might be diminutive in size but it packs a big genetic punch.
Just a few millimetres across, Daphnia pulex is the first crustacean to have its genome sequenced. With 30,907 genes, it has more than any other species sequenced so far, including nearly 5000 more than humans.
Many of the genes are newly evolved to help the water fleas survive climatic changes and exposure to pollutants.
Journal reference: Science (DOI: 10.1126/science.1197761)