The closest family is Plutypus, Monotremata (egg-laying mammals) animal. These two unique and rare animals lay eggs and the baby is fed on Mum's milk. Only two Monotremata are to be found on the earth. It is said that the echidna and the platypus had evolved from the reptilian and it has many of similar character. It is known the fossil record that a platypus-like creature lived long before the Era of Mammals. About 150 million yrs ago, although the ancestors of all mammals laid eggs, only Monotremes have kept this way of giving birth. What is the key to be a mammal? The Mammal is vertebrates (animals with backbones), homeothermic (produce their own body heat) with body hair and provide their young with milk.

ハリモグラに一番近い親戚は、カモノハシ。単孔類といって、哺乳類でありながら卵を産み、おっぱいで子育てをするという、世界でも２種類しかいない非常に珍しい動物。ハリモグラもカモノハシも、爬虫類から進化したといわれる原始的哺乳類で、爬虫類の特徴も多く有すという。この地球上に哺乳類が誕生するずっと以前に、カモノハシによく似た生物が存在したことも、化石から解っている。１億５，０００万年前までは、全哺乳類の祖先は産卵により子孫を残していたとされており、この類い希なる２種の単孔類だけが、その習性を変えず保ち続けている。では、何を以て哺乳類というのか？　哺乳類とは、脊髄と体毛を有し、恒温性で出産後授乳する動物を指す。

The mating season is from June to Septermber. After laying a single, soft-shelled egg, Mum store it in her pouch until it hatches about 10 days later. The Echidna don't have nipples. The milk is secreted from the pores on her belly. The concentrated milk has quite rich nourishment, so that, Mum leaves the baby in the burrow when she forage for food, sometimes for a few days. The baby stay in the pouch until its spines start to grow. At about the age of 7 months old, the young start to live on its own.

交尾期は６〜９月。一回に一つだけ、軟らかい殻の、１円玉より少し小さめの卵を袋の中に産むと、ママはお腹の袋の中で卵が孵化するのを待ちます。約１０日後、卵が孵ります。乳首は無く、ミルクはお腹にある分泌腺（細穴）からでてきます。ミルクはとっても濃厚で栄養価が高く、１回飲んだら数日間は空腹になることもないので、餌探しに出かける時は、巣に赤ちゃんを残していくの。針が生え始めるまで、ママの袋の中で大きくなります。生後７ヶ月を過ぎると、独り立ちして一匹での生活を始めます。

The echidna has the spiny armor, not poisonous, for protection. The spines are useful against predators except the eagles and the Tasmanian Devil, who eat the spines as well. When threatened, they roll into a ball of spines or wedge into a crevice. It has fur btwn the spines (5 cm long). The echidna in Tasmania has thicker and longer fur. The colder the climate, the longer and thicker the fur. The climate changes their habit. In the mainland Australia, the ones live in the sub-tropical area, up north, are completely nocturnal. So, rarely seen during the day time, but in Tasmania, easily found at the day time. The size is 30 to 45 cm long with 2 to 5 kg. The echidna in Tasmania is comparatively larger than the ones in the mainland Australia. They probe into the tunnels of ant and termite nests using their long, narrow snout (teethless) and long tongue. Then they trap the insects on a coating of sticky saliva. The echida is good at swimming. The life span is about 45 yrs.

外的から身を護る保護期間として、体全身に５センチの刺（無毒）が生えてて、危険を感じると顔や手足を丸めて針ボールになったり、穴に逃げ込んだりします。この針は、針を物ともせず食べてしまう鷲やタスマニアデビル以外には有効。針と針の間には毛が生えてて、タスマニアのハリモグラはオーストラリア本土のに比べ大型で、毛は密で多いんだって。これは気候の違いによるもので、寒い地方のハリモグラほど毛深く、またその毛は長くなるそうです。生活スタイルも気候により異なり、本土では北部にゆくほど夜行性が強くなり、亜熱帯地方では完全なる夜行性なので、昼間出逢うチャンスは殆どありません。体長は３０〜４５センチ、体重２〜５キロ。細長い口（無歯）と長い舌を使って、土中や木幹の蟻の巣や、白蟻の蟻塚を探り当てます。そして、粘着力ある唾液で獲物（昆虫）を捕らえるのだ。因みに、水泳が得意。寿命は約４５年。

Vulnerable - endangered animal, the platypus, lives in and along the coastal waterways of Eastern Australia. The platypus is perfectly designed to spend the majority of its lifetime in the water, good diver, good swimmer and good underwater hunter. Formerly the great number of platypuses killed for their fur. And nowadays, due to the pollution of the streams and rivers where they live, the distribution and the numbers of the platypus had severely reduced. Now the platypus is protected by strict law throughout Australia. It is not easy to meet them, the wild ones, unless you are very very lucky. I waited and waited for 3 days then finally saw one swimming in the river. Usually they venture out only in the early morning and evening.

オーストラリア東部の水辺に棲む、絶滅が危ぶまれているカモノハシ。水中生活に見事に適応しており、潜水・遊泳・水中ハンティングが巧いのでも有名。昔は毛皮を採る為に大量に殺され、今は彼等が棲む川の汚染等により、分布域も生息数も激減。現在はオーストラリア全域で、厳しい法律により保護対象となってます。季節にもよるけど、日中であえるチャンスはなっかなか無い。３日間ねばった末、３日目にしてやっと、薄暗〜〜い中で水面を泳ぐ姿にようやっと出逢えた。そりゃー、水族館へゆけば、普通にみられるけど、やはり野性に出逢いたいしょ。主な活動時間は、早朝と夕暮れ時。

Around 1800, at the first glance of the specimen of the platypus, european scientists thought it's a fake. Because they didn't believe that such an animal, which has fur, a duck-like beak, beaver-like tail and lay eggs, can't be exist. In 1802, an English scientist confirmed the creature and finally the platypus splashed its way into natural history. But is still a source of wonder ... part bird, part reptile and part mammal ... is often described as a living fossil. The fossil platypus teeth which found in 63 million yrs old rock in 1991 proved that the platypus was in Argentinean Patagonia, South America. Early platypuses had teeth in the adult phase.

１８００年頃、初めてカモノハシの標本を目にした西欧の科学者達は、毛皮があり、アヒルの様な嘴をもち、ビーバーの様な尻尾があり、しかも卵を産む動物が存在するなんて到底信じられず、偽物だとした。１８０２年、英国科学者がこの謎の生物の存在を確認し、ようやく世界の生物史にお目見えする事となった。が、鳥類・爬虫類・哺乳類の特徴をその体に併せ持つこの動物は、未だ謎の存在で、生きた化石ともいわれている。１９９１年、南米アルゼンチンの６３００万年前の地層から、カモノハシの歯の化石が発見された。初期の成人したカモノハシには歯があったのだ。

Platypus' particularly important features are, the water-resistant fur, the front flat feet, the bill and that they are venomous. Unlike other semi-aquatic animals that have paddles on their rear feet, the platypus has a paddle on its front feet which is formed with a flap of leathery skin that extends past the toes that enable to propel through the water. Webbed hind legs and the tail are only used for steering and as a brake. Large flat furry tail stores fat for the winter in freezing water. The claws on front feet are essential for digging a burrow in a riverbank. Mum lays eggs in the tunnel-like burrow with length of up to 20 meters. When they dive, they shut eyes, ears and nostrils. To search food in the water, the rubbery and soft bill play a great roll. Several small pits on its bill are the sensors and pick up tiny currents in the water that are given off by the nerves and muscles of prey. The bill with approximately 850,000 electrical and tactile receptors is far more sophisticated than those found in fish. It catches crayfish and worms on the bottoms of muddy rivers.

カモノハシの特に重要な特徴は、その耐水性ある毛皮と平たい前足と嘴、そして有毒動物であるということ。前足は、足指よりも長い皮状の弁から成る櫂足になってて、他の水辺の動物とは違い、この前足で泳ぐ。水掻きのある後足と尻尾は、舵取りと制動に使う。尻尾は水が氷のように冷たくなる冬の寒さを凌ぐ為に必要な脂肪の貯蔵庫でもある。前足の鈎爪は川岸に巣を掘るには欠かせない道具。時には２０メートルもの長いトンネルを掘り、ママはこの巣の中で産卵します。嘴は、餌探しにその威力を発揮する。カモノハシは潜水中、目も耳も鼻孔も閉じる。して、嘴のセンサーで、餌であるザリガニや川底の泥の中にいる蠕虫の神経や筋肉から放出される微量の電流をキャッチするのだ。摂受体数８５０，０００個を有すというカモノハシの嘴は、他のどの魚のセンサーよりも巧妙にできていて、どんな小さな動きも、決して見逃す事は無い。

There are burrow of two kinds. One for both adult sexes and one for breeding. The breeding burrow, much deeper and more elaborate, is constructed only by the female and filled with leaves. In bleeding season, from August to October, males fight. How?? With the spurs on the inside of their hind legs. Female loose the spurs before they are mature. Male develop them into defensive poison spurs which seem to used only in the mating season. This feature makes the platypus the only venomous furred creature in the world. Mating takes place in the water in August and September. A month later, Mum lays sticky and soft-skinned eggs in pairs (rarely 1 or 3 eggs : always attached in a triangle when 3 eggs are laid). Mum wait for the babies for a week or so in the nest to come out from the eggs sticked to the fur on her belly. After the hatch, the babies attach themselves to Mum's belly-hairs. An inch long, blind and fur-less babies suckle milk from tufts of hair which is seeped from enlarged milk glands. Platypus' milk is 60 times richer than the milk of cows in iron. At the age of 4 months, the fully furred young emerge from the burrow into the water to swim with their Mum. Children leave the burrow for the last time when they get 6 months old. Most of them leave the area they were born in and start journey to find a home. Though many young die in this process, when they make it, live there for 15 to 20 yrs.

巣には、大人用と子育て用と２種類ある。より深く、作るのに骨の折れる子育て用の巣は、メスだけで作り、巣の中には葉が敷き詰められている。繁殖期である８〜１０月には、オス同士がメスを争ってよく喧嘩します。では一体どうやって？？　後足にある突起物を使って喧嘩をするのです。メスは若い内に失いますが、オスの突起物は有毒性突起物に発達。オスは繁殖期にのみこの器官を使っている様です。有毛な有毒動物というのは、世界でもカモノハシだけ。謎多き生物ですね〜。８・９月の交尾の１ヶ月後、粘着性ある殻の柔らかい卵を２個（稀に１個、３個）産卵。お腹の毛にくっついた卵から赤ちゃん達が産まれるまで約１週間、ママは巣の中でずっと待ちます。まだ目が見えず毛も生えてない、１インチサイズの孵化した赤ちゃんは、自分の体をママのお腹の毛にくっつけ、乳腺から溢れ出てきたミルクを、ミルクで濡れて束になった毛から飲みます。何と、カモノハシのミルクには、牛乳の６０倍の鉄分が含まれてるんだって。生後４ヶ月で毛が生えそろうと、巣を出てママから泳ぎを習得します。生後６ヶ月で独り立ち。この過程で命を落とす子供達は多いけれど、自分の住処を作るべく旅立ち、殆どの個体は異なる水域で巣作りをします。寿命は１５〜２０年。