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一本通書不可以用到老

其實有一個問題已經想了很久, 便是各種品種對不同環境的需求. 正如一般飼養爬蟲類一樣, 飼養蛙類, 我們不能使用同一種飼養方法去飼養不同品種的蛙. 不同品種的蛙類, 有的陸棲性, 有的樹棲性, 又的水棲性, 其飼養缸的佈置方法會有所不同, . 我們要因應牠們的野外生活環境來佈置, 這樣飼養牠們才會長久.

這便是問題所在, 一本通書不可以用到老. 飼養陸寄居蟹也一樣, 雖然在網站內所說的飼養方法基本上可以適用於大部分陸寄居蟹品種. 但想深一層, 陸寄居蟹品種中也有分開居住近海邊, 居住在內陸等地.

看過很多資料, 短腕陸寄居蟹, 凹足陸寄居蟹和西伯利斯陸寄居蟹皆棲身於離海邊遠的地方-離海岸約500米的內陸樹林/雨林(rainforest)裏. 這樣的棲息環境使我想起牠們會不會和住在熱帶雨林的青蛙一樣. 如果是一樣的話, 其實用沙來作底材可能不是最適合牠們的, 用泥土加石子會否更像牠們原生的地方呢!?

灰白陸寄居蟹和紫陸寄居蟹則通常是經常進出內陸與海邊之間.

而橙紅陸寄居蟹, 我找過很多資料也說牠們靠著海邊生活的, 而深紫陸則會在紅樹林一帶出沒. 所以這兩種對海水的要求特別高.

每一種陸寄居蟹都可能有其獨特的生活環境.

一直也有個疑問, 究竟爬蟲類的佈置, 例如地棲蛙類的佈置是否適合這兩種習慣在內陸生活的陸寄居蟹. 即是說以泥土/椰磚作底材, 如可以的話, 更加可以造到一邊是內陸地方, 種植一些真的植物, 放些石子和木頭, 內陸這邊的水盆當然是放淡水. 另一邊是像海邊以沙為底材的地區, 這邊的水盆放海水. 不過考慮的問題也多, 例如用甚麼種類的泥土(爬蟲都好像是用培殖土), 能否像飼養爬蟲類的生態缸般在飼養缸的底部製作疏水的系統, 如果還有自動噴霧器的話便最好. 爬蟲類的佈置方法可否用在陸寄居蟹身上, 我想如果一天我家的空間夠大的話, 或許會嘗試一下. 
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蓋子與濕度的關係

飼養缸的蓋子除了防止陸寄居蟹逃走之外, 其實也有一個重要的作用 - 保持/提高濕度. 陸寄居蟹需要適當的濕度來生活和保持活躍力, 但經常會看到一些大型的飼養缸是沒有蓋子的, 這使我十分懷疑那麼大的飼養缸單靠噴霧的話要很難保持飼養缸內的濕度.

在購了新玻璃缸後, 便作了一個小測試. 本身玻璃缸雖附送蓋子, 但其蓋子只得覆蓋2/3的面積. 使用這蓋子的期間, 發覺因為飼養缸的頂部留有太多空間(下圖), 所以濕度很難維持. 即使噴霧後濕度也不會維持得很久. 可以想像如果連蓋子也不使用, 濕度會更難以維持.



其後便利用一塊自製的亞加力膠板, 在板上開一些孔子, 當作飼養缸的蓋子(下圖). 這新的蓋子能覆蓋缸頂部的面積, 只是邊緣留有少少的位置(方便把蓋拿起). 換了新的蓋子後, 濕度得以維持, 而且也提高了一些. 難怪之前看日本網站的網立說過「陸寄居蟹需要適當的濕度, 所以會以較密封的方法來飼養牠們」. 不要少看蓋子的作用. 蓋子對濕度的控制有一定幫助. 所以, 請大家要使用蓋子來飼養陸寄居蟹.

飼養費用

不要以為你所飼養的只是一隻陸寄居蟹, 便不需要花費很多費用. 其實飼養每一種動物也好, 我們也應該給予牠們最好的.

所以在飼養任何一種動物之前, 也要停一停, 想一想, 想一下我們是否能有能力, 時間, 金錢去飼養牠們.

以下是設置新缸所需的費用($為港幣)

玻璃缸 = $90
5kg沙x3包(未計購買後備沙) = $60
水盆x2個 = $60
木碎1包 = $20
細小流木x2 = 約$40
沉木 = 約$40
溫度計 =$40
濕度計 = $40
自製亞加力膠蓋 = $45
自製背景版 =免費
爬蟲藤 = 約$30
塑膠樹葉 = $25
大螺殼 = $18/個
小螺殼 = $20/6個
自製亞加力分隔板 = $10
海水素1包 = 約$25
日本熱毯 = 約$250
長鉗子 = 約$30
噴水壺 = 約$10
塑膠花盆(做洞穴) = 約$10
共約:$863 (還未計每天所提供的食物, 輔給食物, 日本購買的果凍等等)

一隻小小的陸寄居蟹身價可能不貴(以香港來說), 但要好好的飼養牠們便要花一定費用. 所以千萬不以因牠們身價不高, 以抱著「死了便算吧」,「價錢不高, 買給小朋友玩玩也沒所謂」,「死了下次可再買來飼養」,「蟹, 很容易飼養的吧」.

也請不要因為販賣者說牠們很容易飼養便隨便買回家飼養, 飼養陸寄居蟹, 可不容易!

飼養橙紅陸寄居蟹(Coenobita perlatus)重點在於海水

從以下文章所知, 橙紅陸寄居蟹對海水要求十分高, 因為牠們不會遠離海岸居住, 所以飼養時的要點是一定要有相當高度的海水盆給牠們.

其實在網站內的飼養資料裏也有提及. 海水盆的深度要足夠牠們整隻浸在盆裏.


Geographic Range
Coenobita perlatus is found in the Indo-Pacific from the Islands of Aldabra, Mauritius, and Seychelles through Samoa. These areas are located in the south central Pacific Ocean about 1,600 miles northeast of New Zealand, north of Madagascar and directly above the 10 degree latitude line. (Ingle, 1993)

Habitat
Coenobita perlatus are found living near coastal shorelines. Coenobita perlatus require regular access to the sea or water of high salinity. They are never far from shore or adjacent dunes, and have been found in tidal pools, sandy areas, and humid areas with dune vegetation. Migration occurs from the dune areas to the sea when C. perlatus need to release their eggs into the water or are in need of water to maintain their body moisture. (Hazlett, 1998, Burggren, 1988, Veltman, 1997)

Physical Description
Mass
80 g (average)
(2.82 oz)

Length
800 mm (average)
(31.5 in)

Coenobita perlatus are approximately 80mm long and 80g in body mass. They occupy the multicolored discarded shells of gastropods in order to protect their soft, coiled abdomen and inner organs such as the liver and gonads. These land hermit crabs are decapods, which means they have 10 legs (5 pairs): The first pair is modified as the claws or chelipeds (pinchers), and two pairs of legs are used for walking. The next pair, the claws, are used for defense and transporting food and water to the their mouth. The last two pairs are highly modified but are used more for cleaning than holding on to the shell. When walking, these crabs drag their shells along, but despite this burden, they can run quickly. Each C. perlatus has a loosely fitting carapace that covers the forepart of the body. Coenobita perlatus prefer shells that fit snugly in order to prevent evaporation of moisture and to protect their soft abdomens. Coenobita perlatus have four antennae that help them to sense their surroundings. They have shown some geographic physical variation, but this variations have not been studied in depth.

Male and female C. perlatus can only be distinguished when they are out of their shells. Both the female and male genital pores are located on the coxal ventral surface of each pereiopod (on an appendage of one of the first five abdominal segments), and a long coxal tube (an extension of a pereiopod which is joined broadly to lateral margins of tergites) is present in the male.

(Hazlett, 1998, Burggren, 1988, Veltman, 1997)

Reproduction
These creatures reproduce sexually and will not reproduce in captivity. Reproduction occurs while both individuals are in intermolt (hard-shelled stage), often in or near the burrows of males, or on land near the sea. Male C. perlatus place a spermatophore on the female (externally) which is then dissolved by secretions as the eggs are released. The eggs (about 10,000-50,000 per fertilization) are attached to the pleopods (appendages used for swimming) on the female's abdomen and remain there for some time. Female C. perlatus moisten the eggs with water that is held in the gastropod shell. After the eggs develop, females carry them on their abdomens to the sea, where they leave them on wet sand or a wet rock for the tide to carry them out to sea. The eggs are hatched and the larvae undergo planktonic development. Young C. perlatus are small, molting several times while still at sea in order to reach adult size. They then move to land, where they are vulnerable to their predators until they find a shell. Once C. perlatus have found shells, they live on land the rest of their lives. (Hazlett, 1998, Burggren, 1988, Ingle, 1993, Veltman, 1997)

Lifespan/Longevity
Longest known lifespan in wild
25-30 years (high)

Expected lifespan in captivity
1-4 years (average)

Coenobita perlatus can live up to 25-30 years in the wild, but once in captivity they typically live from 1-4 years.

Behavior
Despite the common name hermit crab, which alludes to a solitary lifestyle, these are very social creatures. They travel in groups of about 25 and are found, in the wild, living in colonies of up to 100 or more. Coenobita perlatus are nocturnal. During the day, when it is hot, they bury themselves in the damp sand or take shelter under ledges of logs to keep cool and reduce moisture loss. Afternoon tropical sun is a danger to these crabs because they require a certain amount of moisture for their gills to operate properly. If they become too dry, they can suffocate. In addition to taking cover from the sun, they also have gills on their big claw in order to conserve moisture. These gills must be kept wet to maintain good health.

When C. perlatus no longer fit their shells they look for bigger ones. The original occupant of the shell, if still present, is quickly removed, and the aggressor moves into its new home. If frightened, land hermit crabs may grasp things tightly with their claws. Even the smallest C. perlatus can draw blood if scared. (Hazlett 1988, Ingle 1993)

Communication and Perception
Coenobita perlatus have been observed communicating to one another by making sounds referred to as chirping. They use their antennae to sense smells and have excellent vision. They are also sensitive to vibrations.

Food Habits
Known as "garbage collectors of the seashore," Coenobita perlatus individuals are scavengers, eating a variety of dead and rotting material found along the seashore. These crabs, in general, do not fight over food and can often go long periods of time without food or water. Most C. perlatus carry water in their shells, which the use for breathing and as a water source when they are far from the sea. (Ingle, 1993)

Economic Importance for Humans: Positive
Coenobita perlatus can be used as a source of food for humans, but are most commonly found as household pets. They also play a vital role in seashore clean-up because they are scavengers. By ridding the shoreline of dead sea matter and other material that collects on the shore, hermit crabs are beneficial in keeping the shoreline clean and creating a healthier environment for humans and other aquatic and coastal organisms. (Veltman, 1997)

Humans are currently the greatest danger to Coenobita perlatus. Though these creatures are not going extinct and are not yet endangered, we humans are destroying their habitats, collecting the crabs for food, over- collecting for pet shops, and polluting the environment. There are many conservation actions currently taking place that affect C. perlatus indirectly. These include shoreline clean-up of human pollution, and prevention of pollution by factories and barges. Pollution is a great threat to C. perlatus because they need a healthy environment to reproduce properly, a safe place to grow their eggs, and clean land and water to live on and drink from.

Other Comments
Growth on land is accomplished by the shedding of their exoskeleton. It takes about ten days for their skin to harden after molting, and as they grow larger, they search out roomier shells to more comfortably accommodate thier bodies. (Hazlett, 1998, Veltman, 1997)


不過過去在飼養橙紅陸寄居蟹時因為還未找到相關資料, 所以一直只用淡水來飼養, 雖然牠能成功脫殼2次, 但飼養了1年多後便死亡. 所以我想重要是牠沒有吸取到所需要的鹽分.

上文還有講及橙紅陸寄居蟹能在野外生存25-30年(大部分), 但在飼養下只能活存1-4年(平均).

濕沙區成功!?

新的缸裏分開了乾沙區和濕沙區. 為的是希望牠會在濕沙區易於挖掘沙堆而成功脫殼. 不知是否時間巧合(剛好遇到牠將近脫殼!?), 搬到新缸的隔天晚上已經有在濕沙區掘沙的舉動. 接著來的幾天也看到牠到濕沙區掘了一個又一個的洞, 但沒有躲藏著. 



今天早上更換食物時不見牠的蹤影, 只聽到"沙~沙~沙~"的聲音, 這便是牠在掘沙的聲音. 看看濕沙區, 也沒有看到牠的蹤影, 很明顯這次牠已經在沙底裏了. 觀察多一陣子, 終於發現牠在近缸邊的位置, 在沙底下約2cm的位置挖掘沙中, 看來這次可以躲藏起來了. 不過即使在沙地下躲藏起來, 過幾天也可能會返回地面. (估計沒錯, 晚上看到牠返回沙上了)



所以, 還是觀察多一陣子才知道濕沙區的作用是否成功. 不過耐近脫殼這件事(因為開始掘沙)是可確定的了. 因為平時牠到不太活動, 只會在晚上出來進食, 其餘時間都是在洞穴內休息.

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