8 Facts Revealed by Genetic Analysis of the Platypus
Adam Rifkin stashed this in Platypus!
Genetic analysis proves that the platypus is confounding well beyond its external mismatched/mish-mashed characteristics:
Fur + Mammaries + Eggs + Feet + Eyes + Poison + Sexy Bits + Electro-Sensory System
The platypus’ eyes alone have been the subject of much publication, possessing (again) a mosaic of characteristics found in disparate animal orders. For instance, they have a rod/cone balance that most closely resembles that of other mammals, but also have a “double cone” thing going on, a feature not found in eutherian mammals (mammals that give birth to fully developed young) or marsupials. Meanwhile, their eyeballs are enclosed by a type of cartilage more like that seen in birds, reptiles, amphibians, sharks, rays, and lungfish.
Male platypuses have pretty mean built-in weapons: spurs on their hind legs that are loaded with a venom potent enough to kill a dog and debilitate a human for days. While there are a few other types of venomous mammal out there, this type of venomous sting could be considered a more reptilian-like trait; that is, the venom itself is made up of organic material similar to the venom in reptiles. However, according to the platypus genome, that organic material gets made via variations in different genes than in reptiles. Reptilian result, uniquely platypusal cause.
The sex of the platypus is determined by a set of ten chromosomes, which, according to platypus geneticist Jennifer Graves, “are absolutely, completely different from all other mammals. We had not expected that.” Each platypus sperm contains either all X or all Y chromosomes. And the platypus X chromosome looks more like the Z sex chromosome that shows up in birds.
In case you weren’t yet convinced that the platypus is “special”: It hunts via a system called electroreception, which is exactly as rad as it sounds. The skin in its bill is highly sensitive, and its combination of touch receptors and electroreceptors (comparable to those found in electric fish) pick up on movements and low-frequency electrical signals in its prey. That’s why, even hunting underwater, at night, the platypus can still bring home the bacon.