Topics: Mammal, Chordate, Platypus Pages: 3 (902 words) Published: November 13, 2012
Phylum Chordata classifies some of the most unique animals of our time. These animals all are common in a certain way. All chordates have vertebrae, a notochord that runs beneath the dorsal nerve cord, and pharyngeal slits or openings in the throat. Additionally, all chordates have a post-anal tail that is almost always lost, a closed circulatory system and lastly, a beating heart. These derived features indicate their common ancestry. Although this phylum contains animals with many structural similarities, evolution and adaptations to selected environments forced animals to change to be able to survive and reproduce. A member of Phylum Chordata, the platypus is just one of these thousands of animals that have to compete to make a name for itself in its environment. It’s amazing how these chordates evolved from simple little organisms like tunicates to complex terrestrial amniotes like mammals. The platypus or Ornithorhynchus anatinus is an animal of Phylum Chordata. This bizarre animal is about the size of a house cat and is covered by thick waterproof hair. Platypuses have a beak like a duck, webbed forearms swimming, clawed hind feet for aid in burrowing, and a broad, flat beaver tail. Also, platypuses have a common opening for the reproductive, excretory, and digestive systems. Male platypuses have sharp venomous stingers on the heels of their hind feet to intoxicate any foe that threatens it. Males are also larger than females in size being 20 inches long and females only being about 17 inches. Their average weight is roughly three to five pounds. Platypuses’ jaws are built differently than other mammals. They have extra bones in their jaw and different muscles. It is a very unique animal and was hard to classify by scientists because it is a monotreme. Being a monotreme, platypuses are one of a few species of mammals that can lay eggs. Also, monotremes are known to have a sese of electroreception. This means that they can...
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