扁形動物(wu)門(men)(Platyhelminthes)渦蟲(chong)(chong)綱(Turbellaria)的代表動物(wu)。Planaria指(zhi)真渦蟲(chong)(chong)屬,而(er)planarian一詞則(ze)指(zhi)片蛭科(Planariidae)及近緣科的動物(wu)。渦蟲(chong)(chong)生(sheng)活在淡水(shui)溪流中的石塊下(xia),以活的或死的蠕(ru)蟲(chong)(chong)、小甲殼(ke)類及昆蟲(chong)(chong)的幼(you)蟲(chong)(chong)等為食物(wu)。
扁形(xing)動物門(men),渦蟲綱(Tubellaria)中淡水生(sheng)活的習(xi)見種(zhong)類,屬三腸目(Tricladida)。
世(shi)界(jie)上已發現近400種,我國記錄(lu)7種,以日本(ben)三角(jiao)渦蟲(Dugesiajaponica)分布最廣,這也(ye)是亞洲(zhou)東部常見的(de)一種。且(qie)日本(ben)三角(jiao)渦蟲在我國分布極(ji)其(qi)廣泛,從臺灣、香港、云南、福建至(zhi)北(bei)京、遼寧(ning)、吉林絕大多數省(sheng)市均有分布。
海產渦(wo)蟲(chong)中(zhong)許(xu)(xu)多是(shi)原始種類,多腸目(Polycladida)渦(wo)蟲(chong)的腸有許(xu)(xu)多側枝;無(wu)腸目(Acoela)無(wu)腸;單腸(Rhabdocoelida)的腸為一直管。有的自(zi)由生(sheng)活,少數寄生(sheng)。陸生(sheng)的土蠱(Bipalium),生(sheng)活在山區(qu)潮(chao)濕(shi)隱蔽處(chu),最長(chang)的可(ke)達1尺。
用(yong)放大鏡或在體(ti)(ti)視(shi)顯微(wei)鏡下觀(guan)察。可見(jian)渦蟲體(ti)(ti)扁(bian)長(chang),背(bei)部微(wei)凸,灰褐色(se);體(ti)(ti)前(qian)端(duan)呈三角形(xing),兩側(ce)略突(tu)起(qi)稱(cheng)耳突(tu),前(qian)端(duan)背(bei)面(mian)(mian)、耳突(tu)內側(ce)有一(yi)對黑色(se)眼點;體(ti)(ti)后(hou)端(duan)稍尖。用(yong)解剖針將蟲體(ti)(ti)翻至腹面(mian)(mian)向(xiang)上,可見(jian)其腹面(mian)(mian)較扁(bian)平(ping),顏(yan)色(se)較淺,密(mi)生纖(xian)毛,腹面(mian)(mian)近體(ti)(ti)后(hou)1/3處有口(kou)。
體(ti)(ti)呈葉片(pian)狀,柔軟,有(you)(you)纖毛。頭鏟形,有(you)(you)兩(liang)眼,有(you)(you)時(shi)具觸須。尾(wei)尖。口在(zai)(zai)(zai)腹(fu)面后側,常在(zai)(zai)(zai)近體(ti)(ti)后1/3處。無體(ti)(ti)腔(qiang)。咽可從口內(nei)伸出(chu)(chu),咽下(xia)接腸,腸為(wei)盲管(guan)。體(ti)(ti)長一般約3~15公厘(0.1~0.6寸),有(you)(you)的超過30公分(fen)(約1尺(chi))。熱帶種色鮮艷,北美的Dugesia屬黑灰或褐(he)色,波浪式游泳或匍(pu)匐(fu)前(qian)進。多數(shu)肉(rou)食(shi)性(xing),夜出(chu)(chu)取食(shi)原生動物、小螺和蠕(ru)蟲。雌雄同體(ti)(ti)。生殖器在(zai)(zai)(zai)初秋(qiu)開始發育。春(chun)季產出(chu)(chu)含受精卵的卵繭,發育不經(jing)變(bian)態。平角渦蟲屬(Planocera)有(you)(you)一幼蟲期在(zai)(zai)(zai)卵內(nei)度過。有(you)(you)些種在(zai)(zai)(zai)產卵繭后身體(ti)(ti)一分(fen)為(wei)二,每一半又長成(cheng)新(xin)(xin)個(ge)體(ti)(ti)。微口渦蟲屬(Microstomum)的尾(wei)端能長出(chu)(chu)新(xin)(xin)個(ge)體(ti)(ti),稱(cheng)為(wei)芽,能附在(zai)(zai)(zai)母體(ti)(ti)上一段時(shi)間,有(you)(you)時(shi)3或4個(ge)芽組成(cheng)鏈狀。渦蟲由于再生能力強而常用(yong)于實驗。
渦蟲(chong)(chong)大(da)多生活在潔凈富氧的(de)海水或(huo)淡(dan)水中(zhong)(zhong)。生活在溪(xi)流淺水處的(de),多隱于石塊下面(mian),晝伏夜出。身體(ti)(ti)柔軟(ruan),頭部具眼點(dian)和耳(er)突,體(ti)(ti)呈(cheng)樹葉形(xing),背(bei)腹扁平,腹面(mian)密生纖(xian)毛,可(ke)爬行(xing)。全體(ti)(ti)淡(dan)褐色,長10余毫米。頭呈(cheng)三(san)角(jiao)形(xing),背(bei)側有(you)(you)1對黑色眼點(dian),兩側各(ge)有(you)(you)一(yi)(yi)(yi)耳(er)突,為嗅覺器官。體(ti)(ti)末端鈍尖(jian)。體(ti)(ti)中(zhong)(zhong)部稍后(hou)(hou)處的(de)腹中(zhong)(zhong)央有(you)(you)口,連(lian)于咽(yan)(yan)(yan)囊,囊內有(you)(you)一(yi)(yi)(yi)肌肉性(xing)管(guan)狀(zhuang)的(de)咽(yan)(yan)(yan),可(ke)伸出體(ti)(ti)外(wai)(wai)。咽(yan)(yan)(yan)與腸相(xiang)(xiang)連(lian),腸分3枝(zhi),1枝(zhi)向(xiang)前(qian),2枝(zhi)向(xiang)后(hou)(hou)。渦蟲(chong)(chong)以(yi)蠕蟲(chong)(chong)、甲殼類、昆蟲(chong)(chong)等(deng)為食(shi),咽(yan)(yan)(yan)吸住食(shi)物(wu)后(hou)(hou),腸即分泌(mi)消(xiao)化液(ye),使之(zhi)溶(rong)為液(ye)狀(zhuang)物(wu),再吸入腸內,進(jin)行(xing)消(xiao)化。不(bu)能消(xiao)化的(de)食(shi)物(wu)殘渣,仍由口排出。無肛(gang)門(men)。養分為腸壁吸收,貯存于實(shi)質中(zhong)(zhong)。代謝產物(wu)由原腎(shen)管(guan)排除(chu),許多排泄孔位(wei)于背(bei)側。呼吸作用經體(ti)(ti)表進(jin)行(xing)。雌雄同體(ti)(ti),生殖(zhi)器官復(fu)雜,生殖(zhi)孔位(wei)于口后(hou)(hou)。生殖(zhi)時(shi),二(er)渦蟲(chong)(chong)尾端一(yi)(yi)(yi)段腹面(mian)相(xiang)(xiang)貼在一(yi)(yi)(yi)起(qi),生殖(zhi)孔相(xiang)(xiang)對,互相(xiang)(xiang)交換(huan)精(jing)子。卵(luan)在體(ti)(ti)內受(shou)精(jing),數個受(shou)精(jing)卵(luan)和卵(luan)黃(營養物(wu)質)被生殖(zhi)囊分泌(mi)的(de)粘液(ye)形(xing)成的(de)膜狀(zhuang)卵(luan)繭包(bao)裹,排出體(ti)(ti)外(wai)(wai),在外(wai)(wai)界孵(fu)化成幼渦蟲(chong)(chong)。渦蟲(chong)(chong)再生力極強(qiang),是(shi)一(yi)(yi)(yi)種很(hen)好的(de)實(shi)驗材料(liao)。橫切(qie)為2段或(huo)多段,每段均可(ke)再生成一(yi)(yi)(yi)完(wan)整的(de)渦蟲(chong)(chong)。
野外采回的(de)渦(wo)蟲(chong),可移入金魚缸(gang)(gang)或其他玻璃容器內飼(si)(si)養(yang)。飼(si)(si)養(yang)缸(gang)(gang)必須很干(gan)凈,否則就會影響(xiang)渦(wo)蟲(chong)正常生(sheng)活,甚至(zhi)會引起死亡。另外,渦(wo)蟲(chong)有避光的(de)習性,飼(si)(si)養(yang)缸(gang)(gang)要放(fang)(fang)在陰涼處,缸(gang)(gang)內放(fang)(fang)些采集地帶(dai)回的(de)小石(shi)塊。缸(gang)(gang)口蓋上一層(ceng)紗布,以(yi)防蚊子(zi)等(deng)產卵(luan)。飼(si)(si)養(yang)水(shui)最好用(yong)井水(shui),如用(yong)自來(lai)水(shui),須放(fang)(fang)2-3天后(hou)才可使用(yong)。
渦(wo)(wo)蟲(chong)(chong)喜食易消(xiao)化的動物性食物,可(ke)(ke)(ke)用(yong)新鮮的動物肝(gan)臟(zang)或煮熟(shu)蛋黃(huang)喂(wei)餌,也可(ke)(ke)(ke)喂(wei)少量魚(yu)蟲(chong)(chong)。一般每(mei)周(zhou)飼食一次,可(ke)(ke)(ke)在換(huan)水前(qian)進行。可(ke)(ke)(ke)把肝(gan)或蛋黃(huang)分成指甲大的小塊,投入缸(gang)底,渦(wo)(wo)蟲(chong)(chong)會(hui)很快地吸(xi)附其上,伸出咽取食。幾小時后,渦(wo)(wo)蟲(chong)(chong)的體(ti)色(se)(se)會(hui)有明(ming)顯的變(bian)(bian)化;喂(wei)肝(gan)時體(ti)色(se)(se)變(bian)(bian)深,喂(wei)蛋黃(huang)時體(ti)色(se)(se)變(bian)(bian)黃(huang)。
及時(shi)換(huan)新鮮水(shui)(shui)(shui)(shui)是飼養(yang)(yang)渦(wo)(wo)蟲的(de)關鍵,在夏季尤為(wei)重要。換(huan)水(shui)(shui)(shui)(shui)時(shi),用毛筆將渦(wo)(wo)蟲一一移(yi)(yi)入(ru)盛有清(qing)水(shui)(shui)(shui)(shui)的(de)臨時(shi)容(rong)器里,把飼養(yang)(yang)缸內的(de)水(shui)(shui)(shui)(shui)倒掉,并刷洗干凈,再注入(ru)清(qing)水(shui)(shui)(shui)(shui),最后將渦(wo)(wo)蟲移(yi)(yi)回。渦(wo)(wo)蟲對水(shui)(shui)(shui)(shui)質(zhi)(zhi)很敏感,一旦飼養(yang)(yang)水(shui)(shui)(shui)(shui)開始變質(zhi)(zhi),渦(wo)(wo)蟲就會離開水(shui)(shui)(shui)(shui)底石塊,或(huo)浮(fu)上水(shui)(shui)(shui)(shui)面,或(huo)不安地游動,這時(shi)應立(li)即(ji)換(huan)水(shui)(shui)(shui)(shui)。