Biologists always considered platypus as one of the most unique animals that is so hard to accurately classify in any phyla of the animal kingdom. It now makes sense how correctly confused they had always been about this egg-laying mammal.
The platypus is classified as a monotreme, an egg-laying mammal with a single opening for reproduction and excretion. But is it truly a mammal? With its webbed feet, a tail like a beaver’s, a coat of fur, and a large bill, it nurses its egg hatched offspring through a set of glands on its abdomen. The answer to this question is full of doubt yet only backed by a satisfactory explanation.
A draft of the genetic sequence of Glennie, a female platypus in Australia has somewhat been able to answer this intriguing yet very confusing question. “We found that the platypus has reptilian, avian, and mammalian genome features in one organism,” says Mark Batzer, a biologist at Louisiana State University.
This mix of genes, he says supports the classification of the platypus as a unique and very early mammal. Among its oddities: 52 chromosomes, including 10 sex chromosomes, as well as the highest number of repeated segments in the genome of any mammal sequenced so far.
He repeats are mobile elements called transposons, also known as jumping genes, which can trigger mutations in the genes around them and lead to genetic disorders. Batzer says, “Learning when transposons first appeared may give us some insight into how they spread through the mammalian lineage and how they are expressed in humans.”
So, platypus can now be proud of being the one animal with three very different ancestors. Talk about ancestral diversity!