Platypus Genes Are Just as Odd as the Creature Itself

These egg-laying, lactating animals have genes in common with mammals as well as birds

Platypus
If the platypus looks like a mixture of bird and mammal features, it's because it is. University of Sydney / Doug Gimesy

Researchers recently published the most complete, detailed platypus genome ever along with the first fully sequenced, short-beaked echidna genome in the journal Nature.

Besides their freaky appearances, these Australian animals are biological oddities because they lay eggs despite having fur, being warm blooded and nursing their young with milk. These egg-laying weirdos, called monotremes, split from other mammals roughly 187 million years ago and studying their genes may help researchers better understand the evolution of the first mammals, reports Cara Giaimo for the New York Times.

"The complete genome has provided us with the answers to how a few of the platypus’ bizarre features emerged,” says Guojie Zhang, a geneticist at the University of Copenhagen and co-author of the paper, in a statement. “At the same time, decoding the genome for platypus is important for improving our understanding of how other mammals evolved—including us humans.”

Zhang adds that the genomes of these two monotremes “hold the key” to figuring out why humans and our mammalian kin give birth to live young instead of laying eggs. Initial analyses suggest the genes reflect exactly what would be expected from a creature that looks like a duck crossed with a beaver. That is to say, it’s an evolutionary mish-mash, sharing milk genes with mammals, and some egg-laying genes with birds and reptiles, reports Carly Cassella for Science Alert.

The platypus genome was first sequenced in 2008, but the quality and completeness of this new genome analysis is a massive improvement, Zhang tells the Times. The new genome is 96 percent mapped, meaning individual genes are in their proper locations on the chromosomes, compared to 25 percent in 2008.

More thoroughly mapped genomes will facilitate future research into the platypus and echidna and their lineage’s unique position at the base of the mammalian evolutionary tree. This more detailed genetic accounting of the platypus and short-beaked echidna could also have exciting biomedical applications, according to a statement from the University of Sydney. Researchers working on the two species’ genomes discovered genes responsible for making previously unknown types of antimicrobial peptides, says Katherine Belov, a geneticist at the University of Sydney and co-author of the paper, in the statement.

These unique peptides could have something to do with the fact that the platypus doesn’t have nipples. Instead, the female platypus sweats out milk through glands on her stomach.

“We believe that the novel antimicrobial peptide genes that we found are secreted by mothers through their milk, to protect their young from harmful bacteria while they are in burrows,” says Belov in the statement.

Because of their special properties, Belov says these newly discovered peptides might give rise to novel drugs to help fight off bacteria, fungi and viruses.