Which animal is one of the few mammals that lays eggs? Which creature has fur and a beak? It sounds like something out of a science fiction or fantasy movie, but it is real. This animal is called the duck-billed platypus.

Platypuses live in eastern Australia. They are small, about the size of a house cat. The male platypus has spurs on its hind feet that can be filled with poison. It uses the spurs to defend itself from animals that might try to kill it. Although the platypus's venom is very powerful and able to kill smaller animals, it isn't strong enough to kill humans. Nevertheless, the pain caused by the venom can be terrible.

Platypuses have webbed feet and swim in streams and rivers. They use their duck-like beak to catch crayfish and other small animals living in the muddy riverbeds. Their bills look hard, but they are actually very sensitive. They even have nostrils on their beaks that they can open and close. When they find something to eat in the muddy water, their beaks allow them to strain the water out while keeping their prey trapped inside. The body and tail of the platypus are covered with dense brown fur that keeps the animals dry and warm.

Many scientists say that platypuses are the strangest animals in the world. This is mainly because they lay eggs and have venom, even though they are warm-blooded mammals. Only one other kind of mammal lays eggs.

Some people consider this egg-laying, venomous, duck-billed, otter-footed mammal "one of nature's jokes" or "an elaborate fraud." Platypuses may be funny looking, but they certainly are interesting. The world would be a less interesting place without them.

唯一卵生的哺乳類是什麼動物？哪一種生物同時擁有毛皮與喙嘴？雖然聽起來像是科幻或奇異電影裡的角色，卻是真實存在的物種。此動物就是「鴨嘴獸」。

鴨嘴獸居住於澳洲東部，體型嬌小，約與家貓一般大。雄鴨嘴獸的後肢有尖刺，會分泌毒液，這是牠避免其他動物掠食自己的防身武器。雖然鴨嘴獸毒液的毒性強烈且足以讓小動物致命，對人類而言卻還不到致死的程度。然而，毒液卻會造成可怕的劇痛。

鴨嘴獸四肢有蹼，可於河流小溪裡游泳。牠們會以鴨嘴般的喙嘴捕食淡水螯蝦和其他居住於 泥濘河床的小動物。喙嘴看似堅硬，其實非常敏感。喙嘴上甚至還有可開閤的鼻孔。當鴨嘴獸在泥漿裡覓食，喙嘴能將水排出，同時把獵物困於嘴裡。鴨嘴獸的軀幹和尾部均佈滿茂密的棕色毛皮，能讓鴨嘴獸保持乾燥保暖的狀態。

許多科學家表示，鴨嘴獸是世界上最光怪陸離的動物。主要原因在於溫血哺乳類動物的鴨嘴獸，竟然會產卵且具有毒液的構造。而目前除了鴨嘴獸外，只剩另一種卵生哺乳類動物。

有些人認為會產卵、分泌毒液、具有鴨嘴和水獺足部構造的此哺乳類動物，彷彿是「大自然 的一個玩笑」或「刻意拼湊的缺陷」。鴨嘴獸雖然外表逗趣，卻是耐人尋味的生物。如果這世上沒有鴨嘴獸，肯定會少了些趣味。