The duck-billed platypus is considered the strangest mammal on earth, as this animal has a set of strange characteristics. It lays eggs like birds instead of giving birth, and it passes milk like a mammal but through its skin. It also has a duck-like beak, flora fur, a hook-like tail, two venomous forks on the male’s hind feet, and 10 sex chromosomes.
The platypus belongs to the order Monotremata, which existed millions of years ago, and even before any known mammal appeared today. However, these strange characteristics have made this animal – which is native to the eastern coasts of Australia – the subject of interest to scientists since its discovery in the late 18th century.
A complete genetic map
Recently, a team of scientists at the University of Copenhagen in Denmark conducted an extensive genetic survey of this strange animal, hoping to find out the secret of its strange features. Scientists were able in this recent study published in the journal Nature on January 6. This January of drawing the full platypus genome.
“The complete genetic map of the platypus provided answers to how the platypus acquired some of these strange traits,” according to the official statement issued by the University of Copenhagen in response to the study.
“Of course, knowing the genetic code for the platypus is important, because it explains why we and other mammals are creatures that give birth to their young instead of laying eggs,” he says.
He ovulates and nurses his young
Mammals are divided into 3 main orders: single-track mammals with one pathway to urination, defecation and sexual reproduction, and marsupials, and placentals, to which we humans belong. The last two groups fall under the class of primates that give birth to their young.
However, monotropic mammals – to which the platypus belongs – differs from both groups. The platypus is a mixture of mammals, birds and reptiles genetically, because it “has preserved many of the features of its original ancestors, which may have been the reason for its ability to adapt to the environment. He lives there, Chan said.
Although the platypus is ovulating, it contains mammary glands that deliver milk as sweating through the skin to feed its young. Scientists do not know exactly when these three mammalian orders began to differentiate from each other. Whereas some believe that monotheism was the first to differentiate, others believe that the three groups diverged at about the same time.
Lost and acquired genes
Chickens are known to contain the three vitellogenin genes that are important for producing yolk (yolk), the same genes that humans miss. The study showed that the platypus still contains one of these genes, so it lays eggs thanks to this gene, but it lost the other two genes nearly 130 million years ago.
While all mammals have replaced the phyllogene genes with the casein genes responsible for producing the casein protein, the main milk component, the platypus also had the casein genes, so its glands secrete milk just as other mammals do.
Unlike most mammals, the platypus has two toothless beak plates that it uses to chew food, another distinguishing feature. The study showed that the platypus lost its teeth nearly 120 million years ago, when 4 of the eight genes responsible for tooth development disappeared.
While humans have two chromosomes responsible for determining sex, they are the “X” (X) and “Y” (Y), so the “X” chromosome meets in the female (XX), while the male has the “X” and “Y” (XY) . The platypus has 10 sex chromosomes, 5 of the “X” and 5 of the “Y” chromosome, and is thus the only animal with 10 sex chromosomes.
By comparing the sex chromosomes of a platypus with the genes of humans, lizards, the Tasmanian devil and the marsupial mouse, scientists found that its sexual chromosomes are more closely related to birds than to humans.