Scientists that were trying to learn more about sex determination in a type of fish mixed eggs and sperm from two different species of fish in a control experiment not intended to yield viable embryos, and ended up creating a hybrid, nicknamed the sturddlefish.
Animal hybrids are unusual in nature, though some exist. The mule is a cross between a female horse and a male donkey, while a liger is created by crossing a female tiger and a male lion, for example. While hybrids can sometimes be created, they are usually sterile. Over the years, scientists have learned more about why this sterility happens. While chromosomal rearrangements may play a role, especially in plants, in animals it seems to be due to incompatibility between specific portions of the genome.
The New York Times reported that scientists in Hungary created what has been popularly named the sturddlefish using eggs from the Russian sturgeon and American paddlefish sperm. These two species last shared a common ancestor around 184 million years ago - which is almost twice as long as the divergence between mice and humans.
The scientists reported their experiment in the journal Genes. They are assuming that these animals are sterile and they said they don't plan to make more of them.
The sturddlefish is carnivorous like its mother, and some of them carried a smaller version of the elongated nose seem on their father, which feeds by filtering.