墨西哥蠑螈有很多不同的名稱，如墨西哥鈍口螈、墨西哥虎螈、美西螈、墨西哥行走魚等，在香港 飼養墨西哥蠑螈的人不多，但知道這種生物的人，通常都叫牠們做六角龍。顧名思義，特徵是左右兩邊各長有三隻「角」，這些角其實是腮。跟大部分蠑螈不同，六 角龍雖然屬兩棲類動物，但事實上並非真的兩棲，終其一生只會在水中活動。
墨西哥蠑螈（學名Ambystoma mexicanum，英文名Axolotl）
這些體色灰黑的正常六角恐龍其實正是墨西哥蠑螈的幼體蝌蚪.而這種蝌蚪最特別的地方就是牠們並不會像一般兩棲類一樣變態進化為陸棲蠑螈.反而 是終其一生無論是成長,性成熟或是繁殖,都著保持幼體的型態,生物學上稱之為「幼體性熟」(neoteny).
六角恐龍只產於墨西哥的薩 奇米丘湖(Lake Xochimilcho)和巧克湖(Lake Chalco).由於墨西哥蠑螈與北美虎皮蠑螈是同科近親,有很多人把虎皮蠑螈的幼體也稱為六角恐龍,這並不正確,雖然兩者的外型體色類似,但是虎皮蠑螈 幼體是會自行進化為蠑螈的,而且虎皮蠑螈幼體花紋還是與六角恐龍稍有不同.近年來美國業者大量繁殖六角恐龍,野生個體已經少見.同時也培養出純白色的白 子,在近兩年更培養出黃金色的白子,大幅提升了六角恐龍的質感.也使得原生體色的六角恐龍反而日漸稀少. 六角恐龍的再生能力非常高強,尤其是幼體,可以在一個月內再生任何斷離的四肢.隨著成長,再生能力會逐漸減弱,無法再生四肢,但是仍然可以再生表皮或手指 腳趾等組織.在自然環境中,六角恐龍並不會進化為蠑螈,如果要強迫牠們進化,必須提高水中碘離子的含量或是在食物中添加甲狀腺激素(thyroxine) 荷爾蒙. 由於六角恐龍是完全水棲的蠑螈幼體,因此飼養牠們的設備可以比照飼養熱帶魚的魚缸佈置.六角恐龍可以長到30公分長,所以飼養缸以三尺以上較為合適.需要 密植水草.最值得注意的重點是,六角恐龍所需的溫度比一般蠑螈更低,因為在原產地的湖水都是由冰雪溶化注入而成的,所以水溫最好保持在20度以下到15度 之間.因此不但需要冷卻機,而且還需要冷卻力較高的冷卻機才能在夏天保持這種低溫.六角恐龍的食量特大,任何魚蝦活餌或是各種飼料只要吞得下都照單全收, 在群養時不能體型差異太大,以免體型小的個體被吞食. 雌雄的辨別在成體十分容易,雄性體型較苗條,泄殖腔腫大凸起,雌性體型肥大,泄殖腔平坦.幼體是無法辨別雌雄的.在繁殖缸中雄性會先產下精囊,雌性接著將 精囊吸入泄殖腔完成交配.雄性在交配後需撈出繁殖缸,雌性在交配後12-20小時內會產卵,數量在200-400顆之間,蠑螈卵與蛙卵一樣都是包覆在一層 透明膠質中,最好分別放置於孵化缸中,每缸不超過50顆卵.在室溫下約15-20天會孵化為幼體蝌蚪,幫助蝌蚪脫離膠質後就可以餵食豐年蝦.幼體蝌蚪最好 也分離單獨飼養以避免弱肉強食,幼體間都有強烈互相吞食的傾向.蝌蚪成長快速,在充足的餵食下,約一年就可以達到性成熟開始繁殖.六角恐龍體健易養,適合 做為新手入門的蠑螈飼養.
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Miss Silver 銀妹
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Mr. Golden 金仔
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The unusual features of axolotls The axolotl is the young, or larva, of a type of salamander and is found in Lake Xochimilco in central Mexico. Amazingly, it can stay as a larva, living its whole life in the water without changing into a grown up salamander. Axolotls can breed while remaining in the larva stage - this unusual ability is called 'neotony'. Another unusual thing about axolotls is that it can grow back body parts that are lost or bitten off by a predator. They can grow back legs or tail, and even parts of the brain or heart.
This is called regeneration Breathing
An axolotl has three pairs of feather-like gills at the back of its head. As water passes through the gills, the axolotl takes in the oxygen from it. From time to time an axolotl will come to the water surface to gulp a breath of air. Life cycle Axolotls can breed when they are about 6 months old. The male axolotl deposits packets of his sperm and then leads the female over them. She takes some of the sperm into her body through an opening called a cloaca. Inside her body the sperm mixes with her eggs. In the next day or two the female lays her eggs on leaves of plants or on rocks. When they hatch, in about two weeks time, the the young axolotls are about a centimetre long and look like frog tadpoles with legs.
Axolotls can live for more than 10 years in captivity. Housing a pet axolotlAxolotls are popular pets and can be housed in an aquarium. One or two axolotls of about the same size can be kept in the same tank but make sure there is plenty of room for the animals to move about. Put in plants, and place a rock, plastic pipe or even a flower pot on its side in the tank so they have a place where they can hide. The water should be filtered and changed from time to time. Aquarium fish may bite at the axolotl's gills so it is best to not put fish and axolotls together.
Diet
Axolotls are carnivores, which means they eat meat. They find their food by sight and by scent.
A pet axolotl should be fed earthworms, crickets or tiny pieces of meat. Some axolotls will eat fish food pellets. Any uneaten food should be removed from the water or it will go bad and make the axolols sick.
Sydenham, S. & Thomas, R. Axolotls [Online] www.kidcyber.com.au (2002).
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