The Platypus
A Unique Australian Mammal
The platypus (Ornithorhynchus anatinus) is endemic to Eastern Australia and Tasmania. It, unlike other mammals, lays eggs instead of giving birth to live young. In addition, it is one of the few venomous mammals known. Once hunted for its pelt, it currently enjoys protection by the Australian government, throughout its habitat.
Morphology
The platypus is a semi-aquatic mammal that has a broad body and a flat tail that contains its fat reserves. Their feet are webbed and it has a broad duck-like snout. The snout is sensory in nature, with its mouth underneath it. The eyes and nose of the platypus are located in a crease right behind the rubbery duck-like bill. The platypus spends most of its time swimming in water, foraging for food. They move about using their front legs mainly in a rowing motion. Males contain ankle spurs on their forelegs. Poison glands, beneath the ankle spur, secrete venom that can inflict a very painful wound. Females don't develop functional ankle spurs or poison glands.
Behavior
The platypus is a solitary animals that usually only comes together to mate. They tend to be shy and are most active in the early morning and evening hours. Besides feeding and mating, they spend countless hours on land and like to groom themselves. One unusual characteristic is that they like to wedge themselves between a rock or tree and the ground. During wedging the platypus’ metabolic rate is less than when it’s resting at the surface. Scientists feel that it may do this in order to rest and conserve its energy. The platypus is capable of emitting a variety of sounds, especially when upset. The most common one tends to be a soft growling sound when disturbed.
Food
The platypus is a carnivore that eats mainly worms, larvae, shrimp and crayfish. An adult platypus can weigh more than five pounds and needs to consume half its weight in food on most days. The platypus can locate its food by electrolocation. Electroreceptor cells in the front of the platypus’ bill can detect the electrical fields of the muscular contractions of its prey, thereby directing the platypus to its prey. Once caught, the prey is placed in cheek pouches and brought to the surface, where it is consumed.
Venom
A male platypus contains venomous ankle spurs that are located on its forelegs. The venom produced is non-lethal to humans, but is capable of inflicting a painful wound. The affected area becomes edematous and in some cases, long-term hyperalgesia can result. Since males are the only gender to possess this venom and venom production appears to peak during breeding season, there's speculation that these spurs may mainly be used as a male dominance factor and secondarily as a means of protection.
Monotremes and reproduction
The platypus is one of five species of mammals that are monotremes. Monotremes are unique mammals that lay eggs instead of live young. The mating season occurs between June and October and appears to be polygamous in nature. After mating, the female platypus builds a deep burrow where she will lay anywhere from one to three leathery eggs. The eggs develop for approximately a month in utero and when laid, incubate for another ten days outside. When born, the female takes care of its young for three to four months. The platypus lacks nipples and instead secretes its milk out through its pores. Grooves on its abdomen collect the milk and allows the young to drink it. The male platypus takes no part in the upbringing of the young.
The platypus is an Australian mammal that exhibits many unusual characteristics. Besides its strange appearance, it lays eggs and is venomous, unlike many other mammals. Once hunted, the Australian government currently protects it and it’s hoped that despite being under environmental stress, the current protection will help ensure its survival.
References
Burrell, H. (1974). The Platypus. Rigby, Adelaide
Grant, Tom. The platypus: a unique mammal. Sydney: University of New South Wales Press, 1995
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