在一陣子乾旱之後的連續大雨後，我們就有機會看見蚯蚓在夜晚至清晨間整隻爬出地表，在路面上漫遊，究竟是什麼原因讓蚯蚓有這樣的行為？蚯蚓的排泄多以氨及尿素為主。而氨與尿素具有一定的毒性，排泄時需要水分來稀釋。當環境乾旱時，蚯蚓體內水分短缺，排泄必定受到影響。針對雨後會爬出的Amynthas robustus 以及無雨後爬出紀錄的Metaphire posthuma，利用模擬乾旱及乾旱後降大雨，測量蚯蚓體內和體外含氮廢物的變化，並藉由模擬環境含氮廢物濃度升高情形，觀察蚯蚓對含氮廢物的耐受力。實驗結果發現，兩種蚯蚓的排泄均會受乾旱影響，而在體內有累積增加的現象，並會藉由降雨的水分來恢復體內水分及滲透壓，並排除累積於體內的含氮廢物，加上土壤泡水後亦會釋出部份的含氮廢物，土壤中含氮廢物的濃度會升高。然而A. robustus對於環境中氨或尿素的忍受度皆不如M. posthuma，因此這可能就是造成A. robustus在乾旱後大雨會爬出地面漫遊，而Ｍ. posthuma不會爬出地表的重要因素。

Abstract
After series heavy rainy days, it is possible to see earthworms coming out from soil, and wondering on the road from night to dawn. This biological mystery has never been experimentally unraveled because earthworm excreted predominantly urea or ammonia; they need sufficient water to excrete these nitrogenous wastes out. During desiccation, body water loss from earthworms must affect their excretion of urea or ammonia. In this study, two species of earthworms, Amynthas robustus and Metaphire posthum, with different behavior after series heavy rainy days was compared.（A. robustus has been observed wondering on soil surface after rains and M. posthuma does not show similar behavior.）The urea and ammonia concentration of earthworm’s blood and of excretion solutions were measured when those earthworms were kept at a mimic situation from drought to a heavy rain after drought. In addition, urea or ammonia was added into the soil to test the endurances of earthworms in the nitrogenous condition. The result demonstrated that during drought, earthworm’s internal concentrations of urea and ammonia increased. However, when water added into the drought soil to mimic heavy rain situation, the dehydrated earthworms can recover their blood nitrogenous concentration to normal state in couple hours. Actually, the urea and ammonia amounts were increased in the excretion solution at the first hour of rehydration in both species. Totally, the nitrogenous concentration of the rehydrated soil was significantly increased due to earthworm excretion. However, the endurance to nitrogenous wastes of M. posthuma is better than A. robustus, this may be the main reason to explain that A. robustus come out of soil after a heavy rain but M. posthuma don’t.

目次
前言 ----------------------------------------------------- 1
材料與方法
實驗動物 ------------------------------------------------- 5
土壤濕度降低時，土壤深度對蚯蚓是否爬出地表之影響 --------- 5
模擬野外乾旱狀況 ----------------------------------------- 5
模擬降雨後，蚯蚓在水中進行含氮廢物的排放 ----------------- 6
環境中含氮廢物對蚯蚓爬出地表的影響 ----------------------- 6
土壤遇大雨泡水所釋放之含氮廢物 --------------------------- 7
血液採樣 ------------------------------------------------- 7
肌肉採樣 ------------------------------------------------- 7
含氮廢物的測量 ------------------------------------------- 7
肌肉中乳酸的測定 ----------------------------------------- 8
資料分析 ------------------------------------------------- 8
結果
蚯蚓對乾旱的耐受性 --------------------------------------- 9
乾旱對蚯蚓鑽土行為之影響 --------------------------------- 9
測量蚯蚓體重及體內含氮廢物濃度在模擬乾旱及乾旱後降大雨的變化 9
蚯蚓乾旱後泡水時，含氮廢物的排泄 ------------------------ 10
環境中含氮廢物對蚯蚓爬出地表的影響 ----------------------- 11
土壤遇大雨泡水時含氮廢物的釋放 --------------------------- 12
討論 ----------------------------------------------------- 13
參考資料 ------------------------------------------------- 20
附錄一
表一 兩種蚯蚓於正常溼度及乾旱情形下，血液中含氮廢物平均濃度之比較------------- 23
表二 比較兩種蚯蚓在正常狀況及乾旱後，泡水時體外所排泄氨量的變化---------------- 24
附錄二
圖一 有底圓柱體及示意圖------------------------------- 25
圖二 蚯蚓所在之柱狀土層隨時間增加之溼度變化圖------------- 26
圖三 蚯蚓在柱狀土層中隨著時間增加的分布情形--------------- 27
圖四 A. robustus在乾旱及乾旱後泡水之體重變化圖------------ 28
圖五 模擬乾旱及乾旱後下大雨泡水的情形下，M. posthuma血液中含氮廢物的濃度變化 29
圖六 模擬乾旱及乾旱後下大雨泡水的情形下，A. robustus血液中含氮廢物的濃度變化 30
圖七 比較蚯蚓在正常狀況下及乾旱後，泡水時所排泄出尿素量的變化---------------------- 31
圖八 A. robustus在氨1%濃度下，死亡個體身體外徵------------ 32
圖九 土壤泡水後所釋放之含氮廢物的累積濃度----------------- 33
圖十 蚯蚓在模擬乾旱及乾旱後大雨，肌肉內乳酸量的變化------ 34

參考資料
Abe, A. S. and Nilce, C. M. (1985) Oxygen binding properties of erythrocruorin solution and blood pH of the giant earthworm Glossoscolex paulistus (oligochaeta, glossoscolecidae). Comparative Biochemistry and Physiology., 80A(1), 53-55.
Bailey, P. T. and Kovaliski, J. (1993) Summer quiescent behavior of the millipede Ommatoiulus moreletri (Julida: Julidae). Journal of Zoology ( London), 231(4), 523-532.
Banta, P. A., Welsford, I. G. and Prior, D. J. (1990) Water-orientation behavior in the terrestrial gastropod Limax maximus the effects of dehydration and arginine vasotocin. Physiological Zoology, 63(4), 683-696.
Bouché, M. B. (1972) Lombriciens de France. Ecologie et Systématique. Institut National de la Recherche Agronomique, Paris.
Chew, S. F., Yi, J. and Yuen, K. I. (2001) The loach Misgurnus anguillicaudatus reduces amino acid catabolism and accumulates alanine and glutamine during aerial exposure. Physiological and biochemical zoology, 74(2), 226-237.
Curry, J. P. (1998) Factors Affecting Earthworm Abundance in soils. In Earthworm Ecology, (ed C. A. Edwards), Soil and Water Conservation Society, Ankeny, Iowa. P37-56.
Darwin, C. (1881) The formation of vegetable mould through the action of worms, with observation of their habits. Murray, London. P1-3.
Davis, J. G. and William, K. S. (1928) XLV. The anaerobic metabolism of the earthworm (Lumbricus terrestris). The biochemical journal, 22, 338-343.
Dickinson, P. S., Prior, D. J. and Avery, C. (1988) The pneumostome rhythm in slugs a response to dehydration controlled by hemolymph osmolarity and peptide hormones. Comp. Biochem. Physiol. A, 89(4), 579-586.
Durand, F. and Michèle, R. (1998) Nitrogen metabolism of two protunid crabs, Carcinus maenas and Necora puber, during prolonged air exposure and subsequent recovery: a comparative study. The journal of experimental biology, 201, 2515-2528.
Durand, F., Fabinne, C. and Michèle, R. (1999) Increases in tissue free amino acid levels in response to prolonged emersion in marine crabs: an ammonia-detoxifying process efficient in the intertidal Carcinus maenas but not in the subtidal Necora puber. The journal of experimental biology, 202, 2191-2202.
Edwards, C. A. and P. J. Bohlen. (1996) Biology and Ecology of earthworms. 3rd edition, Chapman & Hall, London, UK.
Edwards C. A. (ed.) (1998) Earthworm Ecology. Soil and Water Conservation Society, Ankeny, Iowa.
Gerard, B.M. (1967) Factors affecting earthworms in pastures. Journal of Animal Ecology, 36, 235-252.
Holmstrup, M. (2001) Sensitivity of life history parameters in the earthworm Aporrectodea caliginosa to small changes in soil water potential. Soil biology & biochemistry, 33, 1217-1223.
IP, Y. K., Cheng, B. L., Shit, F. C., Jonathan, M. W. and David, J. R. (2001) Partial amino acid catabolism leading to the formation of alanine in Periophthalmodon schlosseri (mudskipper): A strategy that facilitates the use of amino acids as an energy source during locomotory activity on land. The journal of experimental biology, 204, 1615-1624.
Jonathan,W., O’Donnell, M. J. and Sazgar, S. (1997) Haemolymph osmoregulation and the fate of sodium and chloride during dehydration in terrestrial isopods. Journal of insect physiology, 43(9), 795-807.
Lim, C. B., Shit, F. C., Paul, M. A. and Yuen, K. I. (2001) Reduction in the rates of protein and amino acid catabolism to slow down the accumulation of endogenous ammonia : a strategy potentially adopted by mudskipper (Periophthalmodon schlosseri and Boleophthalmus boddaerti) during aerial exposure in constant darkness. The journal of experimental biology, 204, 1605-1614.
Madge, D. S. (1969) Field and laboratory studies on the activities of two species of tropical earthworms. Pedobiologia, 9, 188-214.
Merker, E. and Brauning, G. (1927) Die empfindlichkeit feuchthäutiger tiere im lichte. 3. Die atemont feuchthäutiger tiere in licht der quarzquecksiblerlampe. Zool. Jb. Abt. Allgm. Zool. Physiol. Tiere, 43, 275-338.
Morris, S. and W. J. Van Aardt (1998) Salt and water relations, and nitrogen excretion, in the amphibious African freshwater crab Potamonautes warreni in water and in air. The journal of experimental biology, 201, 883-893.
Nordström, S. (1975) Seasonal activity of lumbricids in southern Sweden. Oikos, 26, 307-315.
Philip, W., Pedler S. and Guppy M. (1997) Physiological adjustments during aestivation by the Australian land snail Rhagada tescorum (Mollusca: Pulmonata: Camaenidae). Australian Journal of Zoology, 45(6), 599-611.
Zeev, A. (2001) Desiccation and rehydration in land snails: A test for distinct set points in Theba pisana. Israel Journal of Zoology, 47(1), 41-53.
廖光正、李明進（2002）集集大地震後蚯蚓大量爬出現象之解析. 特有生物研究, 4(1), 41-51.
行政院環保署，化學物質毒理資料庫，編號: HSN-162。http://www.twdep.gov.tw/www/d50/d51/tox/toxdata/7617.htm
莊淑君（1999）兩種蚯蚓的耗氧研究。動物行為暨生態研究會論文摘要，第c01頁。