Most people only know that platypuses (Ornithorhynchus anatinus) are cute, yet ridiculous looking monotreme, or egg laying, mammals from Australia. In reality, there is much more to them than that. Although it might not seem like it because of the small, slightly obscured eyes, the platypus actually has fairly acute vision over long distances. However, it can’t use this sense when diving under water to search for prey. When it dives, the platypus closes its eyes, ears, and nostrils to keep out water. To navigate and hunt, it relies on its ability to sense the electrical currents given off by its preys’ muscular contractions every time they move. This is called electrolocation or electroreception. Electroreceptors along its bill allow it to gauge the direction it needs to go by determining the strength of the signal. This is why a platypus will constantly sweep its head side to side while on the hunt. It is trying to analyze the signal strength to locate its prey. In addition to the electroreceptors on its bill, the platypus also possesses mechanoreceptors which detect touch. The place in the brain that processes the electrosensory signals is located in the tactile somatosensory area and some of the cells there can receive input from both the mechano and electroreceptors. This suggests that there is a very close relationship between these two forms of sense.
Platypuses have very dense, luxuriously soft fur and were formerly hunted for their pelts because of this. They are generally dark, grayish brown on their backs and creamy white on the belly. The top layer of fur, called guard hair, is coarser and helps insulate the platypus by trapping a layer of air and locking out water when swimming.
In addition to their peculiar egg laying trait, they also have a wicked self defense method. They are one of the very few known venomous mammals. Both sexes of platypus are born with calcaneus spurs near their hind feet, but the male’s contain a potent cocktail of toxins specifically designed to cause pain and incapacitate an opponent. These toxins have been found to directly target pain receptors in the brain and a dose of them can result in agony that can last for up to a few weeks or longer. It is not fatal to humans, but it has been known to kill smaller animals such as dogs. They may be irresistibly cute and cuddly, but before you go grabbing up and hugging the next platypus you come across, think carefully about how you do that.
1. Pettigrew, J. D., P. R. Manger, and S. L. B. Fine. “The sensory world of the platypus.” Philosophical Transactions of the Royal Society B: Biological Sciences 353.1372 (1998): 1199-1210.
2. De Plater, G. M., P. J. Milburn, and R. L. Martin. “Venom from the platypus, Ornithorhynchus anatinus, induces a calcium-dependent current in cultured dorsal root ganglion cells.” Journal of neurophysiology 85.3 (2001): 1340-1345.
3. “Wildlife Queensland – Platypus.” Wildlife Queensland – Platypus. Wildlife Queensland, n.d. Web. 20 Apr. 2015. .