Sturdlefish is “Impossible” Paddlefish/Sturgeon hybrid

Scientists have managed to cross-breed Paddlefish and Sturgeon while attempting to save an endangered species. Eggs from three Russian sturgeon were fertilized artificially with sperm from four American paddlefish in an experiment to produce gynogenic sturgeon eggs (eggs that only contain genes from the mother.) Non-irradiated paddlefish sperm was used and unexpectedly it produced viable hybrid fry with over a 60% survival rate.  

Hybridisation is natural and even part of evolution, but although both the ancient species share a common ancestor, they split 180 million years ago, and now have very different morphology, habitat, feeding methods, and even come from separate continents. There is no mistaking the American paddlefish, Polyodon spathula, with its huge, spoon-shaped rostrum, large mouth and gill rakers like a Basking shark, which it uses to filter feed on microorganisms as it swims constantly through midwater. 

Sturgeons from the genus Acipenser look even more shark-like but have pointed ridges along their backs, short, pointy noses and underslung mouths for sucking up larger invertebrates from the river bed. Both ancient families are endangered with the Paddlefish’s larger cousin, the Chinese paddlefish, recently being declared extinct and many of the 27 sturgeon species being listed on CITES appendices. 

Like many hybrids the young were variable in their resemblance to one or other of the parents, although by and large, they resembled the sturgeon mother in morphology and mouthparts. There are no previous reports of successful hybridization of acipenserids and polyodontids and previous, deliberate attempts have been unsuccessful. 

For more info go to MDPI.