A crabby lesson learnt

One late morning, I was awakened by a phone call from Mr. Leung. Normally, a teacher doesn’t call a student just to chat or something, therefore, I knew immediately that something important happened.

What I was told was that 5 horseshoe crabs had died during the night. It was shocking news, not only because it broke our record of having the most deaths of horseshoe crabs in one day, but also because I had been on duty for four days including that day (but I over-slept!)

We believe that the mysterious death was caused by decay of the excessive amount of food shrimps which were not eaten by the crabs. The food shrimps must have been left for too long and caused bacterial production! A few days in the tank, the food shrimp can cause a large amount of bacteria as the environment made for the crabs is also suitable for bacteria to grow - oxygen pumped in for the crabs, at the same time, provides enough oxygen for the bacteria to grow; moisture is surely enough (man-made salt water). Moreover, the temperature controlled by us is always about 30 degrees which is the best temperature for all bacteria to reproduce.

A feeling of guilt was with me. Was it my fault by feeding too much? Or was it something else that caused the death of the crabs? No one knows yet.

Horseshoe crabs are weak at their larvae stage, so they could be easily infected by its surroundings. Horseshoe crabs are rare and we do not dare to loss any one of them. But as I just said, the crabs are still weak. There is still a high chance for more crabs to die. But from what I learnt, the only thing we can do is to try our best to prevent the same thing from happening again. In other words, solutions must be suggested.

As the old folks say “Every one must have done something wrong before”. So are we going to learn from our mistakes in order to do better? Or are we going to ignore the mistakes? To me, I would rather use this chance to improve myself.

I hope our team can minimize the number of errors that we may encounter in the program because the horseshoe crabs’ life is in our hands……

Chong Szi Yong

活化石

馬蹄蟹,另一個學名叫鱟，馬蹄蟹從4億多年前問世至今仍然保留著它原始而古老的相貌,所以馬蹄蟹有“活化石”之稱。

馬蹄蟹其實不是真正的螃蟹，而是用腮呼吸的原始的節肢動物。香港曾錄有三個出沒在亞洲的馬蹄蟹品種：中國鱟、南方鱟和圓尾鱟。

牠們最愛吃蠕蟲、軟體動物和死魚。在海底爬行時，牠們會用第一對鉗形的腿來 尋找食物，然後用其它有纖毛的腿把食物放進口裏。馬蹄蟹所面對的威脅主要是環境污染導致繁殖 率和存活率下降，環境污染導致繁殖率 和存活率下降海岸發展破壞了牠們的產卵地和保育地。

陳學勤

馬蹄蟹的結構

馬蹄蟹(又名鱟)是從四億多年前至今仍活着的古 老生物, 所以鱟有「活化石」之稱。

牠們的名字是因為牠們的頭部形狀很像馬蹄而得來。牠們有一對複眼在殼的上方, 頭和胸是連在一起的, 接着的是腹部和尾劍。因為牠們是蠍和蜘蛛的近親, 所以馬蹄蟹有很多對腳, 而且牠們的腳都很像蜘蛛和蠍的腳, 只要將牠們反轉, 便可以看到口部、六對節枝和一層層的鰓片。

女的馬蹄蟹通常身長30-40厘米, 男的則比女的短5-10厘米, 因為與異性交配時, 成熟的雄性馬蹄蟹要爬到雌性馬蹄蟹身上, 若果男的體形過大, 則不方便交配。腿部方便, 雄性馬蹄蟹的第二和第三雙腿呈扣狀, 是為了方便在交配是抓緊伴侶。

譚漢賢