Saturday, January 19, 2013

The Duck Billed Platypus


          Since this is the first post I figured I’d start off with one of the most incredible examples of evolution gone insane we know of in the natural world; the duck billed platypus. I know most have heard of the duck billed platypus but I’m still willing to bet most of you out there have no idea just how incredible these little things really are. The first thing you’ll notice when you look at the platypus is that it has a duck bill…. and fur… a beaver tail… and wait are its feet webbed too? What the heck is this thing? Seriously this thing can’t be real it looks like Mr. potato head: animal kingdom edition. Well I assure it isn’t a 7 year olds drawing come to life, it is a real animal and it’s a mammal….. that lays eggs… and the males are venomous…. Seriously this thing is ridiculous.... and adorable.


            The Platypus belongs to a group of mammals called the monotremes, meaning egg laying mammal. They share this grouping with only four other extant species: all species of echidna. All but one of these species is endemic to Australia and the one that isn’t is isolated to the island of New Guinea. Every other known species of mammal is known as a therian mammal, meaning live birth. The monotremes are evidence of one of the earliest splits in the mammalian family tree. Fossil evidence shows this split occurred at least 167 million years ago. This early split goes a long way to explain the radical differences between the platypus and the vast majority of all other mammals. 


 The platypus is a solitary, mostly nocturnal, and semi aquatic animal that lives in slow moving streams in eastern Australia and Tasmania. It feeds by skimming its broad, flat bill side to side on the riverbed in search of food including insect larvae and crustaceans among other invertebrates. When underwater the platypus closes its eyes, ears, and nostrils and uses its bill to find its food. If its bill were like that of a duck this wouldn’t be possible. However, unlike ducks the platypus’s bill is soft and sensitive, chock full of nerve endings able to pick up on the miniscule electric signals its prey gives off. They are the only species of mammal other than certain dolphin species that use a sense of electro-location, which is truly incredible. Once the food is in their mouth they crush it between pads made of keratin, which they have in lieu of teeth, to chew.


            Being a semi aquatic animal, meaning it spends time on land and in water; the platypus has had to evolve features that are suitable for both habitats.  One such feature is their webbed and clawed feet. Their feet are webbed for use in swimming: the front feet are broad and used for propulsion while the hind feet are much smaller and used for navigation and agility. Their claws however are used on land to dig their burrows that they sleep and nest in. Sleep burrows can be up to 50 feet in length while nesting burrows can be even longer with multiple chambers. Another dual-purpose adaptation is their coat of fur. On land the coat is comfortable enough to allow them to live in habitats varying from cold mountain streams to tropical rainforests. In the water however, their coats show off how evolution has truly engineered the platypus for success. First off it is extremely slick; this makes movement under water incredibly easy compared to if their coats were like that of most other mammals. Their coats are also waterproof. Having a waterproof coat is beneficial in two ways, first it also helps with their hydrodynamics making swimming easier but most importantly it traps a layer of air between their fur and skin preventing them from losing body heat in cold water.

 
            One of the most astounding things about the platypus is its method of reproduction. As outlined above the platypus lays eggs. When we’re first taught about mammals as children one of the first things we’re taught that set us apart from the rest of the animal kingdom is that mammals have live young. The platypus however, is one of only 5 species that break that mold. Once the eggs are laid they hatch between one week and two weeks later. Like all mammals the platypus lactates to feed its young but unlike most mammals it doesn’t have teats. Instead the pinkish, white milk (that’s also some of the richest of any mammal) is excreted through pores and the young ingest it off of the mothers fur. 


            Now for the platypus fact that I find the most astounding; the males are venomous. That to me is one of the most out of left field facts about any animal out there. Venom in mammals, although not as rare as egg laying, is incredibly rare.  The males have a small spike just behind their back legs connected to a venom gland that they use to deliver the venom. This spike is used in offense against other males in territorial scuffles or in their heightened state of aggression during mating season. The venom is also used as a defensive weapon against the numerous predators that dine on platypus. This venom is rather potent in that it is strong enough to kill a dog however a human would just experience extreme pain. 


            The duck billed platypus is one of nature’s most astounding creations. Its order has survived millions of years changing very little while the rest of the mammalian class has changed far more significantly. The platypus is a shining example of the quirks of evolution and furthermore the beauty of nature itself.