芒果视频下载

基本介紹

刺(ci)(ci)(ci)(ci)胞(bao)(bao)動物(wu)(wu)門(men)（Cnidaria）又稱(cheng)刺(ci)(ci)(ci)(ci)細胞(bao)(bao)動物(wu)(wu)門(men)，過(guo)去稱(cheng)為(wei)腔(qiang)(qiang)(qiang)腸動物(wu)(wu)門(men)（Coelenterata），因為(wei)它的(de)(de)含(han)義適用(yong)(yong)于(yu)刺(ci)(ci)(ci)(ci)胞(bao)(bao)動物(wu)(wu)及櫛水(shui)(shui)(shui)母(mu)動物(wu)(wu)，所以現(xian)多已廢棄不用(yong)(yong)。刺(ci)(ci)(ci)(ci)胞(bao)(bao)動物(wu)(wu)體呈輻射或(huo)兩(liang)輻射對稱(cheng)，僅具(ju)二胚(pei)層(ceng)(ceng)，是(shi)最原始(shi)的(de)(de)后(hou)生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)動物(wu)(wu)。體壁由外(wai)胚(pei)層(ceng)(ceng)、內胚(pei)層(ceng)(ceng)和(he)(he)中膠(jiao)層(ceng)(ceng)組成。內胚(pei)層(ceng)(ceng)圍成身(shen)體的(de)(de)整個內腔(qiang)(qiang)(qiang)稱(cheng)消(xiao)化(hua)循環(huan)腔(qiang)(qiang)(qiang)，腔(qiang)(qiang)(qiang)腸一(yi)端(duan)為(wei)口(kou)，他端(duan)閉塞，無肛門(men)。體壁中有(you)刺(ci)(ci)(ci)(ci)細胞(bao)(bao)。腔(qiang)(qiang)(qiang)腸動物(wu)(wu)的(de)(de)骨(gu)(gu)骼主要為(wei)外(wai)骨(gu)(gu)骼，具(ju)有(you)支持和(he)(he)保護功能。多由幾丁質、角質和(he)(he)石(shi)灰質構成。在很多珊(shan)(shan)瑚(hu)(hu)(hu)蟲(chong)中具(ju)有(you)骨(gu)(gu)針或(huo)骨(gu)(gu)軸(zhou)，它們存(cun)在于(yu)中膠(jiao)層(ceng)(ceng)，或(huo)突出(chu)于(yu)體表面。有(you)無性(xing)和(he)(he)有(you)性(xing)兩(liang)種(zhong)生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)方式，并(bing)往往出(chu)現(xian)在同一(yi)種(zhong)的(de)(de)生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)活(huo)史(shi)中，即(ji)水(shui)(shui)(shui)螅型世代(dai)用(yong)(yong)無性(xing)出(chu)芽生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)方式產生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)水(shui)(shui)(shui)母(mu)型世代(dai)，而水(shui)(shui)(shui)母(mu)型個體脫離(li)母(mu)體，長大(da)成熟以后(hou)，又以有(you)性(xing)生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)方式產生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)水(shui)(shui)(shui)螅型個體，兩(liang)個世代(dai)互相交替完成整個生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)活(huo)史(shi)。約1萬種(zhong)，可(ke)(ke)分為(wei)：水(shui)(shui)(shui)螅蟲(chong)綱(gang)、缽(bo)水(shui)(shui)(shui)母(mu)綱(gang)和(he)(he)珊(shan)(shan)瑚(hu)(hu)(hu)蟲(chong)綱(gang)3綱(gang)，一(yi)般認為(wei)水(shui)(shui)(shui)螅蟲(chong)綱(gang)是(shi)最原始(shi)的(de)(de)。絕大(da)部分海(hai)產，只有(you)少數(shu)(shu)種(zhong)類(lei)產于(yu)淡水(shui)(shui)(shui)，以熱(re)帶(dai)和(he)(he)亞熱(re)帶(dai)海(hai)洋的(de)(de)淺水(shui)(shui)(shui)區最豐富。較小(xiao)種(zhong)類(lei)可(ke)(ke)作(zuo)魚類(lei)食餌，珊(shan)(shan)瑚(hu)(hu)(hu)骨(gu)(gu)骼（如(ru)紅珊(shan)(shan)瑚(hu)(hu)(hu)）可(ke)(ke)作(zuo)工藝品，古珊(shan)(shan)瑚(hu)(hu)(hu)和(he)(he)現(xian)代(dai)珊(shan)(shan)瑚(hu)(hu)(hu)可(ke)(ke)形成儲油層(ceng)(ceng)，海(hai)邊的(de)(de)珊(shan)(shan)瑚(hu)(hu)(hu)礁可(ke)(ke)作(zuo)天(tian)然海(hai)堤；海(hai)蜇鹽漬后(hou)成為(wei)食品，有(you)些(xie)種(zhong)類(lei)可(ke)(ke)作(zuo)藥用(yong)(yong)；有(you)些(xie)浮游水(shui)(shui)(shui)母(mu)類(lei)可(ke)(ke)作(zuo)為(wei)海(hai)流指示生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)物(wu)(wu)；但是(shi)，有(you)些(xie)大(da)型水(shui)(shui)(shui)母(mu)（如(ru)霞水(shui)(shui)(shui)母(mu)、根口(kou)水(shui)(shui)(shui)母(mu)）在大(da)量出(chu)現(xian)時，會阻塞或(huo)破壞漁(yu)網(wang)，有(you)的(de)(de)海(hai)葵(kui)混于(yu)漁(yu)獲物(wu)(wu)中，人食后(hou)中毒致死。刺(ci)(ci)(ci)(ci)胞(bao)(bao)動物(wu)(wu)除極少數(shu)(shu)種(zhong)類(lei)為(wei)淡水(shui)(shui)(shui)生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)活(huo)外(wai)，絕大(da)多數(shu)(shu)種(zhong)均為(wei)海(hai)洋生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)活(huo)，多數(shu)(shu)在淺海(hai)，少數(shu)(shu)為(wei)深海(hai)種(zhong)，現(xian)存(cun)約11000種(zhong)，分為(wei)3個綱(gang)：水(shui)(shui)(shui)螅綱(gang)（Hydrozoa）、缽(bo)水(shui)(shui)(shui)母(mu)綱(gang)（Scyphozoa）、珊(shan)(shan)瑚(hu)(hu)(hu)綱(gang)（Anthozoa）。

形態及特征

肌肉與運動

刺胞(bao)(bao)動(dong)(dong)(dong)物很少能做主(zhu)(zhu)動(dong)(dong)(dong)的(de)(de)(de)(de)移位運動(dong)(dong)(dong)，運動(dong)(dong)(dong)的(de)(de)(de)(de)能力是(shi)(shi)很有(you)限的(de)(de)(de)(de)，特別是(shi)(shi)水(shui)(shui)(shui)(shui)螅型。運動(dong)(dong)(dong)是(shi)(shi)由(you)(you)表(biao)皮肌(ji)(ji)肉(rou)(rou)細(xi)胞(bao)(bao)中肌(ji)(ji)原(yuan)纖(xian)維(wei)(wei)的(de)(de)(de)(de)收(shou)(shou)縮(suo)所(suo)引(yin)(yin)(yin)起(qi)。例(li)如水(shui)(shui)(shui)(shui)螅的(de)(de)(de)(de)身體(ti)(ti)(ti)可(ke)(ke)做伸縮(suo)運動(dong)(dong)(dong)，伸展時(shi)體(ti)(ti)(ti)長(chang)可(ke)(ke)達(da)15～20mm，收(shou)(shou)縮(suo)時(shi)體(ti)(ti)(ti)長(chang)僅0.5mm，這種伸縮(suo)是(shi)(shi)爆(bao)發(fa)式的(de)(de)(de)(de)，每5～10分(fen)鐘左右爆(bao)發(fa)一次，主(zhu)(zhu)要是(shi)(shi)由(you)(you)外(wai)皮肌(ji)(ji)細(xi)胞(bao)(bao)的(de)(de)(de)(de)縱行肌(ji)(ji)原(yuan)纖(xian)維(wei)(wei)的(de)(de)(de)(de)收(shou)(shou)縮(suo)所(suo)引(yin)(yin)(yin)起(qi)。身體(ti)(ti)(ti)一側(ce)的(de)(de)(de)(de)肌(ji)(ji)原(yuan)纖(xian)維(wei)(wei)的(de)(de)(de)(de)收(shou)(shou)縮(suo)可(ke)(ke)引(yin)(yin)(yin)起(qi)身體(ti)(ti)(ti)的(de)(de)(de)(de)彎曲。有(you)時(shi)靠彎曲身體(ti)(ti)(ti)及觸手并(bing)與基盤的(de)(de)(de)(de)交替附(fu)著(zhu)而(er)做翻斛斗式的(de)(de)(de)(de)運動(dong)(dong)(dong)。基盤處粘細(xi)胞(bao)(bao)可(ke)(ke)分(fen)泌大量(liang)的(de)(de)(de)(de)氣泡(pao)，可(ke)(ke)使水(shui)(shui)(shui)(shui)螅在(zai)(zai)水(shui)(shui)(shui)(shui)面(mian)上做短暫的(de)(de)(de)(de)漂(piao)浮。缽水(shui)(shui)(shui)(shui)母(mu)(mu)類和珊瑚類的(de)(de)(de)(de)肌(ji)(ji)原(yuan)纖(xian)維(wei)(wei)已與表(biao)皮細(xi)胞(bao)(bao)分(fen)離形成(cheng)獨立的(de)(de)(de)(de)一層(ceng)(ceng)肌(ji)(ji)纖(xian)維(wei)(wei)，例(li)如水(shui)(shui)(shui)(shui)母(mu)(mu)的(de)(de)(de)(de)肌(ji)(ji)原(yuan)纖(xian)維(wei)(wei)在(zai)(zai)下(xia)傘(san)(san)(san)面(mian)及傘(san)(san)(san)緣(yuan)形成(cheng)薄薄的(de)(de)(de)(de)一層(ceng)(ceng)肌(ji)(ji)肉(rou)(rou)環(huan)，有(you)的(de)(de)(de)(de)被(bei)輻管分(fen)離成(cheng)片狀(zhuang)，其(qi)纖(xian)維(wei)(wei)有(you)橫(heng)紋，它(ta)們做有(you)規律的(de)(de)(de)(de)收(shou)(shou)縮(suo)，使傘(san)(san)(san)面(mian)有(you)節(jie)奏的(de)(de)(de)(de)收(shou)(shou)縮(suo)運動(dong)(dong)(dong)。當傘(san)(san)(san)緣(yuan)收(shou)(shou)縮(suo)時(shi)，傘(san)(san)(san)緣(yuan)內(nei)的(de)(de)(de)(de)水(shui)(shui)(shui)(shui)被(bei)噴出(chu)，由(you)(you)于反作用(yong)力而(er)推(tui)動(dong)(dong)(dong)水(shui)(shui)(shui)(shui)母(mu)(mu)體(ti)(ti)(ti)向(xiang)(xiang)上運動(dong)(dong)(dong)，當傘(san)(san)(san)及傘(san)(san)(san)緣(yuan)肌(ji)(ji)肉(rou)(rou)舒張(zhang)，被(bei)壓縮(suo)的(de)(de)(de)(de)中膠層(ceng)(ceng)的(de)(de)(de)(de)彈性，使傘(san)(san)(san)又(you)恢復了原(yuan)形，水(shui)(shui)(shui)(shui)又(you)重新進入傘(san)(san)(san)緣(yuan)內(nei)，身體(ti)(ti)(ti)下(xia)沉，但由(you)(you)于收(shou)(shou)縮(suo)比舒張(zhang)要快，所(suo)以(yi)水(shui)(shui)(shui)(shui)母(mu)(mu)還(huan)是(shi)(shi)可(ke)(ke)以(yi)向(xiang)(xiang)上垂直運動(dong)(dong)(dong)。水(shui)(shui)(shui)(shui)母(mu)(mu)類的(de)(de)(de)(de)垂直運動(dong)(dong)(dong)在(zai)(zai)有(you)緣(yuan)膜的(de)(de)(de)(de)水(shui)(shui)(shui)(shui)母(mu)(mu)可(ke)(ke)以(yi)看的(de)(de)(de)(de)更為清楚(chu)。一旦肌(ji)(ji)肉(rou)(rou)停止收(shou)(shou)縮(suo)，水(shui)(shui)(shui)(shui)母(mu)(mu)就(jiu)會(hui)自然下(xia)沉。其(qi)水(shui)(shui)(shui)(shui)平(ping)方向(xiang)(xiang)的(de)(de)(de)(de)運動(dong)(dong)(dong)多是(shi)(shi)被(bei)動(dong)(dong)(dong)的(de)(de)(de)(de)，多是(shi)(shi)由(you)(you)于水(shui)(shui)(shui)(shui)流及風力所(suo)推(tui)動(dong)(dong)(dong)。又(you)例(li)如在(zai)(zai)珊瑚類，海葵的(de)(de)(de)(de)肌(ji)(ji)原(yuan)纖(xian)維(wei)(wei)在(zai)(zai)隔膜上形成(cheng)發(fa)達(da)的(de)(de)(de)(de)牽(qian)縮(suo)肌(ji)(ji)，它(ta)的(de)(de)(de)(de)收(shou)(shou)縮(suo)非常有(you)力，所(suo)以(yi)當海葵固著(zhu)在(zai)(zai)巖石上是(shi)(shi)很難將它(ta)取下(xia)的(de)(de)(de)(de)。

取食與消化

刺(ci)胞(bao)(bao)動(dong)物(wu)(wu)都是(shi)肉(rou)食(shi)性的(de)(de)(de)，以(yi)浮游生物(wu)(wu)，小(xiao)的(de)(de)(de)甲(jia)殼類(lei)(lei)(lei)、多(duo)(duo)毛類(lei)(lei)(lei)甚至小(xiao)的(de)(de)(de)魚類(lei)(lei)(lei)為食(shi)。由(you)于(yu)食(shi)物(wu)(wu)的(de)(de)(de)機械刺(ci)激和化(hua)學刺(ci)激，引起水(shui)螅(xi)類(lei)(lei)(lei)動(dong)物(wu)(wu)伸長觸(chu)手(shou)，并放(fang)出刺(ci)絲(si)囊(nang)以(yi)纏繞、麻痹、毒(du)殺捕獲物(wu)(wu)，再將食(shi)物(wu)(wu)送入口中(zhong)。口區腺(xian)細(xi)胞(bao)(bao)分(fen)泌的(de)(de)(de)粘液(ye)有(you)利(li)于(yu)食(shi)物(wu)(wu)的(de)(de)(de)吞(tun)咽，食(shi)物(wu)(wu)進(jin)入胃(wei)腔后，胃(wei)層的(de)(de)(de)腺(xian)細(xi)胞(bao)(bao)開始分(fen)泌蛋白酶，分(fen)解、消(xiao)(xiao)化(hua)食(shi)物(wu)(wu)使之形成許(xu)多(duo)(duo)多(duo)(duo)肽，同時在(zai)(zai)胃(wei)腔中(zhong)由(you)于(yu)營(ying)(ying)養(yang)(yang)肌(ji)肉(rou)細(xi)胞(bao)(bao)的(de)(de)(de)鞭毛運動(dong)，食(shi)物(wu)(wu)得以(yi)混合與推(tui)動(dong)。經這種(zhong)(zhong)細(xi)胞(bao)(bao)外消(xiao)(xiao)化(hua)之后，開始細(xi)胞(bao)(bao)內(nei)的(de)(de)(de)消(xiao)(xiao)化(hua)過(guo)程(cheng)，營(ying)(ying)養(yang)(yang)肌(ji)肉(rou)細(xi)胞(bao)(bao)的(de)(de)(de)偽(wei)足(zu)吞(tun)噬(shi)食(shi)物(wu)(wu)顆粒(li)，在(zai)(zai)細(xi)胞(bao)(bao)內(nei)形成大(da)(da)量(liang)的(de)(de)(de)食(shi)物(wu)(wu)泡，經過(guo)酸(suan)(suan)性及(ji)堿性的(de)(de)(de)化(hua)學過(guo)程(cheng)之后，營(ying)(ying)養(yang)(yang)物(wu)(wu)質由(you)細(xi)胞(bao)(bao)的(de)(de)(de)擴(kuo)散作(zuo)用(yong)輸(shu)(shu)送到(dao)全(quan)身。缽水(shui)母(mu)類(lei)(lei)(lei)及(ji)珊(shan)瑚類(lei)(lei)(lei)胃(wei)腔結構比較(jiao)復(fu)雜。缽水(shui)母(mu)的(de)(de)(de)胃(wei)腔中(zhong)有(you)各種(zhong)(zhong)輻管及(ji)環管，胃(wei)囊(nang)中(zhong)有(you)內(nei)胚層起源的(de)(de)(de)胃(wei)絲(si)；珊(shan)瑚類(lei)(lei)(lei)的(de)(de)(de)胃(wei)腔被許(xu)多(duo)(duo)隔(ge)(ge)膜分(fen)隔(ge)(ge)成許(xu)多(duo)(duo)小(xiao)室(shi)，隔(ge)(ge)膜上有(you)隔(ge)(ge)膜絲(si)。胃(wei)絲(si)及(ji)隔(ge)(ge)膜絲(si)中(zhong)含有(you)大(da)(da)量(liang)的(de)(de)(de)刺(ci)細(xi)胞(bao)(bao)及(ji)腺(xian)細(xi)胞(bao)(bao)，它們是(shi)將食(shi)物(wu)(wu)吞(tun)入胃(wei)腔之后才(cai)殺死及(ji)消(xiao)(xiao)化(hua)。消(xiao)(xiao)化(hua)后的(de)(de)(de)營(ying)(ying)養(yang)(yang)物(wu)(wu)通過(guo)各種(zhong)(zhong)管道(dao)輸(shu)(shu)送到(dao)全(quan)身，未消(xiao)(xiao)化(hua)的(de)(de)(de)食(shi)物(wu)(wu)殘(can)渣(zha)仍(reng)由(you)口排出。糖元及(ji)脂(zhi)肪是(shi)腔腸動(dong)物(wu)(wu)的(de)(de)(de)主要貯存物(wu)(wu)。刺(ci)胞(bao)(bao)動(dong)物(wu)(wu)中(zhong)許(xu)多(duo)(duo)種(zhong)(zhong)類(lei)(lei)(lei)，特(te)別是(shi)海洋中(zhong)的(de)(de)(de)造礁珊(shan)瑚類(lei)(lei)(lei)，體內(nei)均有(you)共生的(de)(de)(de)藻(zao)類(lei)(lei)(lei)，如動(dong)物(wu)(wu)黃(huang)藻(zao)、腰鞭毛藻(zao)之類(lei)(lei)(lei)。藻(zao)類(lei)(lei)(lei)能進(jin)行光合作(zuo)用(yong)，產生甘(gan)油(you)、脂(zhi)肪、糖及(ji)脯氨酸(suan)(suan)等，并提供給刺(ci)胞(bao)(bao)動(dong)物(wu)(wu)作(zuo)為其(qi)補充(chong)營(ying)(ying)養(yang)(yang)。這將在(zai)(zai)珊(shan)瑚綱中(zhong)做進(jin)一步的(de)(de)(de)敘述。

呼吸與排泄

刺(ci)胞動物沒有專門的呼(hu)(hu)吸(xi)及(ji)排泄器(qi)官，由(you)于(yu)身體是(shi)由(you)兩層(ceng)(ceng)細胞圍繞胃循環腔(qiang)所組成，并通過口(kou)使胃腔(qiang)與(yu)外界(jie)相(xiang)通，實際上(shang)體壁(bi)的兩層(ceng)(ceng)細胞均與(yu)外界(jie)環境接觸，所以呼(hu)(hu)吸(xi)與(yu)排泄作用可以由(you)體壁(bi)細胞直(zhi)接獨立進行(xing)。出、入(ru)口(kou)及(ji)胃腔(qiang)的水流可以攜帶入(ru)新鮮的氧氣，并帶走代謝產物。刺(ci)胞動物的主要含氮(dan)廢物是(shi)氨。

神經傳導及感官

刺胞(bao)(bao)(bao)(bao)動(dong)(dong)(dong)(dong)物(wu)(wu)(wu)(wu)(wu)(wu)是(shi)(shi)(shi)(shi)(shi)最(zui)早(zao)出(chu)現神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)結(jie)(jie)(jie)構(gou)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)多(duo)(duo)(duo)(duo)細(xi)(xi)胞(bao)(bao)(bao)(bao)動(dong)(dong)(dong)(dong)物(wu)(wu)(wu)(wu)(wu)(wu)。神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)結(jie)(jie)(jie)構(gou)原始(shi)，是(shi)(shi)(shi)(shi)(shi)由(you)(you)(you)雙極神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)元(yuan)(yuan)(yuan)(yuan)、多(duo)(duo)(duo)(duo)極神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)元(yuan)(yuan)(yuan)(yuan)及神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)纖(xian)維聯(lian)(lian)合成(cheng)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)叢或(huo)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)網(wang)(wang)(wang)，一(yi)(yi)(yi)(yi)般(ban)位于(yu)外(wai)(wai)表(biao)皮細(xi)(xi)胞(bao)(bao)(bao)(bao)基(ji)部肌(ji)肉(rou)(rou)層之(zhi)(zhi)外(wai)(wai)，呈網(wang)(wang)(wang)狀(zhuang)(zhuang)分(fen)(fen)布，故稱(cheng)(cheng)網(wang)(wang)(wang)狀(zhuang)(zhuang)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)系(xi)統(tong)（netnervous system）。由(you)(you)(you)于(yu)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)細(xi)(xi)胞(bao)(bao)(bao)(bao)可向(xiang)各個(ge)(ge)(ge)(ge)(ge)方向(xiang)傳(chuan)(chuan)(chuan)導(dao)(dao)(dao)(dao)(dao)(dao)(dao)，也(ye)稱(cheng)(cheng)為(wei)(wei)漫散(san)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)系(xi)統(tong)（diffusenervous system）。水(shui)(shui)(shui)(shui)(shui)螅(xi)就只(zhi)有(you)(you)(you)(you)(you)(you)(you)(you)一(yi)(yi)(yi)(yi)個(ge)(ge)(ge)(ge)(ge)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)網(wang)(wang)(wang)，但(dan)大多(duo)(duo)(duo)(duo)數腔(qiang)腸動(dong)(dong)(dong)(dong)物(wu)(wu)(wu)(wu)(wu)(wu)除了表(biao)皮的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)網(wang)(wang)(wang)之(zhi)(zhi)外(wai)(wai)，在(zai)(zai)胃層的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)基(ji)部也(ye)有(you)(you)(you)(you)(you)(you)(you)(you)一(yi)(yi)(yi)(yi)個(ge)(ge)(ge)(ge)(ge)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)網(wang)(wang)(wang)，這(zhe)(zhe)兩(liang)(liang)(liang)個(ge)(ge)(ge)(ge)(ge)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)網(wang)(wang)(wang)或(huo)是(shi)(shi)(shi)(shi)(shi)完(wan)全(quan)獨立的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)，或(huo)有(you)(you)(you)(you)(you)(you)(you)(you)纖(xian)維相(xiang)聯(lian)(lian)。1971年Westfall等(deng)首先證明(ming)了水(shui)(shui)(shui)(shui)(shui)螅(xi)及其他腔(qiang)腸動(dong)(dong)(dong)(dong)物(wu)(wu)(wu)(wu)(wu)(wu)在(zai)(zai)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)元(yuan)(yuan)(yuan)(yuan)之(zhi)(zhi)間(jian)(jian)(jian)、神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)元(yuan)(yuan)(yuan)(yuan)與效應器（表(biao)皮肌(ji)肉(rou)(rou)細(xi)(xi)胞(bao)(bao)(bao)(bao)、刺細(xi)(xi)胞(bao)(bao)(bao)(bao)、腺細(xi)(xi)胞(bao)(bao)(bao)(bao)等(deng)）之(zhi)(zhi)間(jian)(jian)(jian)也(ye)存在(zai)(zai)著突(tu)(tu)(tu)(tu)觸(chu)傳(chuan)(chuan)(chuan)遞(di)(di)（synaptic transmission）。即(ji)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)沖(chong)動(dong)(dong)(dong)(dong)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)傳(chuan)(chuan)(chuan)導(dao)(dao)(dao)(dao)(dao)(dao)(dao)是(shi)(shi)(shi)(shi)(shi)由(you)(you)(you)一(yi)(yi)(yi)(yi)個(ge)(ge)(ge)(ge)(ge)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)元(yuan)(yuan)(yuan)(yuan)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)軸突(tu)(tu)(tu)(tu)，傳(chuan)(chuan)(chuan)遞(di)(di)給另一(yi)(yi)(yi)(yi)個(ge)(ge)(ge)(ge)(ge)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)元(yuan)(yuan)(yuan)(yuan)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)樹突(tu)(tu)(tu)(tu)。軸突(tu)(tu)(tu)(tu)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)末(mo)端具(ju)有(you)(you)(you)(you)(you)(you)(you)(you)突(tu)(tu)(tu)(tu)觸(chu)小(xiao)(xiao)(xiao)泡(pao)（synaptic vesicle），樹突(tu)(tu)(tu)(tu)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)末(mo)端沒(mei)(mei)有(you)(you)(you)(you)(you)(you)(you)(you)。傳(chuan)(chuan)(chuan)導(dao)(dao)(dao)(dao)(dao)(dao)(dao)時(shi)(shi)，突(tu)(tu)(tu)(tu)觸(chu)小(xiao)(xiao)(xiao)泡(pao)釋放乙酰(xian)膽堿引(yin)起(qi)后一(yi)(yi)(yi)(yi)個(ge)(ge)(ge)(ge)(ge)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)元(yuan)(yuan)(yuan)(yuan)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)興奮，沖(chong)動(dong)(dong)(dong)(dong)傳(chuan)(chuan)(chuan)出(chu)以(yi)后，乙酰(xian)膽堿被神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)末(mo)稍表(biao)面的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)膽堿酯酶(mei)水(shui)(shui)(shui)(shui)(shui)解成(cheng)膽堿及乙酸而(er)解除了激活作用。以(yi)后又(you)發(fa)現腔(qiang)腸動(dong)(dong)(dong)(dong)物(wu)(wu)(wu)(wu)(wu)(wu)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)突(tu)(tu)(tu)(tu)觸(chu)傳(chuan)(chuan)(chuan)導(dao)(dao)(dao)(dao)(dao)(dao)(dao)分(fen)(fen)為(wei)(wei)兩(liang)(liang)(liang)種類(lei)型。一(yi)(yi)(yi)(yi)類(lei)突(tu)(tu)(tu)(tu)觸(chu)是(shi)(shi)(shi)(shi)(shi)對稱(cheng)(cheng)性(xing)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)傳(chuan)(chuan)(chuan)導(dao)(dao)(dao)(dao)(dao)(dao)(dao)（symmetrical），即(ji)兩(liang)(liang)(liang)個(ge)(ge)(ge)(ge)(ge)或(huo)多(duo)(duo)(duo)(duo)個(ge)(ge)(ge)(ge)(ge)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)末(mo)端有(you)(you)(you)(you)(you)(you)(you)(you)突(tu)(tu)(tu)(tu)觸(chu)小(xiao)(xiao)(xiao)泡(pao)，因(yin)此沖(chong)動(dong)(dong)(dong)(dong)可以(yi)同(tong)時(shi)(shi)向(xiang)兩(liang)(liang)(liang)個(ge)(ge)(ge)(ge)(ge)或(huo)幾個(ge)(ge)(ge)(ge)(ge)方向(xiang)傳(chuan)(chuan)(chuan)遞(di)(di)，這(zhe)(zhe)種傳(chuan)(chuan)(chuan)導(dao)(dao)(dao)(dao)(dao)(dao)(dao)也(ye)叫非(fei)極性(xing)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)傳(chuan)(chuan)(chuan)導(dao)(dao)(dao)(dao)(dao)(dao)(dao)（nonpolarized transmission）；另一(yi)(yi)(yi)(yi)類(lei)突(tu)(tu)(tu)(tu)觸(chu)是(shi)(shi)(shi)(shi)(shi)不對稱(cheng)(cheng)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)（asymmetrical），即(ji)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)細(xi)(xi)胞(bao)(bao)(bao)(bao)只(zhi)有(you)(you)(you)(you)(you)(you)(you)(you)一(yi)(yi)(yi)(yi)個(ge)(ge)(ge)(ge)(ge)末(mo)端具(ju)突(tu)(tu)(tu)(tu)觸(chu)小(xiao)(xiao)(xiao)泡(pao)，神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)沖(chong)動(dong)(dong)(dong)(dong)只(zhi)能向(xiang)一(yi)(yi)(yi)(yi)個(ge)(ge)(ge)(ge)(ge)方向(xiang)傳(chuan)(chuan)(chuan)導(dao)(dao)(dao)(dao)(dao)(dao)(dao)，因(yin)此也(ye)稱(cheng)(cheng)為(wei)(wei)有(you)(you)(you)(you)(you)(you)(you)(you)極性(xing)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)傳(chuan)(chuan)(chuan)導(dao)(dao)(dao)(dao)(dao)(dao)(dao)（polarized transmission）。最(zui)近的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)研究證明(ming)刺胞(bao)(bao)(bao)(bao)動(dong)(dong)(dong)(dong)物(wu)(wu)(wu)(wu)(wu)(wu)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)非(fei)極性(xing)傳(chuan)(chuan)(chuan)導(dao)(dao)(dao)(dao)(dao)(dao)(dao)是(shi)(shi)(shi)(shi)(shi)很(hen)普遍的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)。也(ye)有(you)(you)(you)(you)(you)(you)(you)(you)人認為(wei)(wei)刺胞(bao)(bao)(bao)(bao)動(dong)(dong)(dong)(dong)物(wu)(wu)(wu)(wu)(wu)(wu)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)兩(liang)(liang)(liang)個(ge)(ge)(ge)(ge)(ge)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)網(wang)(wang)(wang)一(yi)(yi)(yi)(yi)個(ge)(ge)(ge)(ge)(ge)是(shi)(shi)(shi)(shi)(shi)由(you)(you)(you)多(duo)(duo)(duo)(duo)極神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)元(yuan)(yuan)(yuan)(yuan)形(xing)成(cheng)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)非(fei)極性(xing)傳(chuan)(chuan)(chuan)導(dao)(dao)(dao)(dao)(dao)(dao)(dao)，也(ye)就是(shi)(shi)(shi)(shi)(shi)慢(man)傳(chuan)(chuan)(chuan)導(dao)(dao)(dao)(dao)(dao)(dao)(dao)系(xi)統(tong)；另一(yi)(yi)(yi)(yi)個(ge)(ge)(ge)(ge)(ge)是(shi)(shi)(shi)(shi)(shi)由(you)(you)(you)雙極神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)元(yuan)(yuan)(yuan)(yuan)形(xing)成(cheng)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)極性(xing)傳(chuan)(chuan)(chuan)導(dao)(dao)(dao)(dao)(dao)(dao)(dao)，也(ye)就是(shi)(shi)(shi)(shi)(shi)快傳(chuan)(chuan)(chuan)導(dao)(dao)(dao)(dao)(dao)(dao)(dao)系(xi)統(tong)。刺胞(bao)(bao)(bao)(bao)動(dong)(dong)(dong)(dong)物(wu)(wu)(wu)(wu)(wu)(wu)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)元(yuan)(yuan)(yuan)(yuan)可以(yi)有(you)(you)(you)(you)(you)(you)(you)(you)2個(ge)(ge)(ge)(ge)(ge)、3個(ge)(ge)(ge)(ge)(ge)或(huo)多(duo)(duo)(duo)(duo)個(ge)(ge)(ge)(ge)(ge)長的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)突(tu)(tu)(tu)(tu)起(qi)，這(zhe)(zhe)些突(tu)(tu)(tu)(tu)起(qi)或(huo)與感(gan)官相(xiang)聯(lian)(lian)、或(huo)與效應器相(xiang)聯(lian)(lian)、或(huo)與其他神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)元(yuan)(yuan)(yuan)(yuan)相(xiang)聯(lian)(lian)、或(huo)者是(shi)(shi)(shi)(shi)(shi)同(tong)一(yi)(yi)(yi)(yi)個(ge)(ge)(ge)(ge)(ge)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)元(yuan)(yuan)(yuan)(yuan)同(tong)時(shi)(shi)與感(gan)官與效應器相(xiang)聯(lian)(lian)，這(zhe)(zhe)種多(duo)(duo)(duo)(duo)樣(yang)性(xing)說明(ming)了神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)細(xi)(xi)胞(bao)(bao)(bao)(bao)傳(chuan)(chuan)(chuan)導(dao)(dao)(dao)(dao)(dao)(dao)(dao)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)原始(shi)性(xing)。在(zai)(zai)生(sheng)理(li)意義上(shang)代表(biao)了高等(deng)動(dong)(dong)(dong)(dong)物(wu)(wu)(wu)(wu)(wu)(wu)所具(ju)有(you)(you)(you)(you)(you)(you)(you)(you)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)感(gan)覺(jue)(jue)(jue)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)、運動(dong)(dong)(dong)(dong)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)及中樞神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)起(qi)始(shi)階段。此外(wai)(wai)，刺胞(bao)(bao)(bao)(bao)動(dong)(dong)(dong)(dong)物(wu)(wu)(wu)(wu)(wu)(wu)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)非(fei)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)傳(chuan)(chuan)(chuan)導(dao)(dao)(dao)(dao)(dao)(dao)(dao)，即(ji)上(shang)皮傳(chuan)(chuan)(chuan)導(dao)(dao)(dao)(dao)(dao)(dao)(dao)也(ye)是(shi)(shi)(shi)(shi)(shi)很(hen)常見(jian)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)，例如刺細(xi)(xi)胞(bao)(bao)(bao)(bao)、表(biao)皮肌(ji)肉(rou)(rou)細(xi)(xi)胞(bao)(bao)(bao)(bao)可以(yi)完(wan)全(quan)獨立于(yu)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)元(yuan)(yuan)(yuan)(yuan)而(er)被自身所控制。水(shui)(shui)(shui)(shui)(shui)母(mu)型的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)結(jie)(jie)(jie)構(gou)比水(shui)(shui)(shui)(shui)(shui)螅(xi)型復雜，例如水(shui)(shui)(shui)(shui)(shui)螅(xi)水(shui)(shui)(shui)(shui)(shui)母(mu)，除了傘(san)(san)部的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)網(wang)(wang)(wang)之(zhi)(zhi)外(wai)(wai)，傘(san)(san)緣(yuan)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)上(shang)皮神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)細(xi)(xi)胞(bao)(bao)(bao)(bao)分(fen)(fen)別在(zai)(zai)傘(san)(san)緣(yuan)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)上(shang)、下(xia)面集中形(xing)成(cheng)兩(liang)(liang)(liang)個(ge)(ge)(ge)(ge)(ge)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)環。下(xia)面（或(huo)稱(cheng)(cheng)外(wai)(wai)面）的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)一(yi)(yi)(yi)(yi)個(ge)(ge)(ge)(ge)(ge)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)環更(geng)發(fa)達。缽(bo)水(shui)(shui)(shui)(shui)(shui)母(mu)類(lei)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)水(shui)(shui)(shui)(shui)(shui)母(mu)型多(duo)(duo)(duo)(duo)數沒(mei)(mei)有(you)(you)(you)(you)(you)(you)(you)(you)這(zhe)(zhe)種神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)環，而(er)是(shi)(shi)(shi)(shi)(shi)在(zai)(zai)傘(san)(san)緣(yuan)集中形(xing)成(cheng)4～8個(ge)(ge)(ge)(ge)(ge)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)節(jie)。水(shui)(shui)(shui)(shui)(shui)母(mu)型個(ge)(ge)(ge)(ge)(ge)體均能表(biao)現出(chu)一(yi)(yi)(yi)(yi)種有(you)(you)(you)(you)(you)(you)(you)(you)節(jie)奏的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)收縮(suo)(suo)運動(dong)(dong)(dong)(dong)，這(zhe)(zhe)是(shi)(shi)(shi)(shi)(shi)由(you)(you)(you)于(yu)水(shui)(shui)(shui)(shui)(shui)母(mu)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)結(jie)(jie)(jie)構(gou)每(mei)隔一(yi)(yi)(yi)(yi)定時(shi)(shi)間(jian)(jian)(jian)能自發(fa)地產生(sheng)動(dong)(dong)(dong)(dong)作電位，并經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)過神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)傳(chuan)(chuan)(chuan)導(dao)(dao)(dao)(dao)(dao)(dao)(dao)引(yin)起(qi)整個(ge)(ge)(ge)(ge)(ge)身體的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)收縮(suo)(suo)。研究已(yi)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)證明(ming)這(zhe)(zhe)種自發(fa)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)動(dong)(dong)(dong)(dong)作電位是(shi)(shi)(shi)(shi)(shi)由(you)(you)(you)起(qi)博(bo)點的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)元(yuan)(yuan)(yuan)(yuan)所引(yin)起(qi)。起(qi)博(bo)點神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)元(yuan)(yuan)(yuan)(yuan)在(zai)(zai)水(shui)(shui)(shui)(shui)(shui)螅(xi)水(shui)(shui)(shui)(shui)(shui)母(mu)存在(zai)(zai)于(yu)外(wai)(wai)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)環中，在(zai)(zai)缽(bo)水(shui)(shui)(shui)(shui)(shui)母(mu)類(lei)存在(zai)(zai)于(yu)感(gan)官神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)節(jie)中。而(er)且每(mei)一(yi)(yi)(yi)(yi)個(ge)(ge)(ge)(ge)(ge)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)節(jie)（一(yi)(yi)(yi)(yi)般(ban)4～8個(ge)(ge)(ge)(ge)(ge)）都有(you)(you)(you)(you)(you)(you)(you)(you)起(qi)博(bo)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)元(yuan)(yuan)(yuan)(yuan)，它(ta)是(shi)(shi)(shi)(shi)(shi)水(shui)(shui)(shui)(shui)(shui)母(mu)類(lei)有(you)(you)(you)(you)(you)(you)(you)(you)節(jie)奏博(bo)動(dong)(dong)(dong)(dong)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)中心。一(yi)(yi)(yi)(yi)個(ge)(ge)(ge)(ge)(ge)水(shui)(shui)(shui)(shui)(shui)母(mu)體似乎有(you)(you)(you)(you)(you)(you)(you)(you)一(yi)(yi)(yi)(yi)個(ge)(ge)(ge)(ge)(ge)起(qi)博(bo)點就足以(yi)引(yin)起(qi)身體有(you)(you)(you)(you)(you)(you)(you)(you)節(jie)奏的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)收縮(suo)(suo)運動(dong)(dong)(dong)(dong)，但(dan)實(shi)驗證明(ming)多(duo)(duo)(duo)(duo)個(ge)(ge)(ge)(ge)(ge)起(qi)博(bo)點比僅有(you)(you)(you)(you)(you)(you)(you)(you)一(yi)(yi)(yi)(yi)個(ge)(ge)(ge)(ge)(ge)起(qi)博(bo)點能使收縮(suo)(suo)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)節(jie)奏更(geng)有(you)(you)(you)(you)(you)(you)(you)(you)規律、更(geng)有(you)(you)(you)(you)(you)(you)(you)(you)保障、使間(jian)(jian)(jian)隔的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)時(shi)(shi)間(jian)(jian)(jian)也(ye)較(jiao)(jiao)短(duan)。腔(qiang)腸動(dong)(dong)(dong)(dong)物(wu)(wu)(wu)(wu)(wu)(wu)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)水(shui)(shui)(shui)(shui)(shui)螅(xi)型體沒(mei)(mei)有(you)(you)(you)(you)(you)(you)(you)(you)明(ming)顯的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)感(gan)官，其感(gan)覺(jue)(jue)(jue)細(xi)(xi)胞(bao)(bao)(bao)(bao)可分(fen)(fen)布全(quan)身，但(dan)觸(chu)手、口區較(jiao)(jiao)為(wei)(wei)豐富。水(shui)(shui)(shui)(shui)(shui)母(mu)型個(ge)(ge)(ge)(ge)(ge)體，在(zai)(zai)傘(san)(san)緣(yuan)具(ju)有(you)(you)(you)(you)(you)(you)(you)(you)豐富的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)感(gan)覺(jue)(jue)(jue)細(xi)(xi)胞(bao)(bao)(bao)(bao)或(huo)感(gan)覺(jue)(jue)(jue)器官。感(gan)覺(jue)(jue)(jue)細(xi)(xi)胞(bao)(bao)(bao)(bao)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)細(xi)(xi)胞(bao)(bao)(bao)(bao)體都是(shi)(shi)(shi)(shi)(shi)具(ju)纖(xian)毛(mao)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)。感(gan)覺(jue)(jue)(jue)器官包括眼點及平(ping)衡囊(nang)。眼點是(shi)(shi)(shi)(shi)(shi)由(you)(you)(you)感(gan)覺(jue)(jue)(jue)細(xi)(xi)胞(bao)(bao)(bao)(bao)構(gou)成(cheng)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)杯狀(zhuang)(zhuang)物(wu)(wu)(wu)(wu)(wu)(wu)，內有(you)(you)(you)(you)(you)(you)(you)(you)色(se)素顆粒分(fen)(fen)布，它(ta)對光(guang)線或(huo)有(you)(you)(you)(you)(you)(you)(you)(you)正趨性(xing)，即(ji)有(you)(you)(you)(you)(you)(you)(you)(you)光(guang)時(shi)(shi)游向(xiang)水(shui)(shui)(shui)(shui)(shui)面。或(huo)對光(guang)有(you)(you)(you)(you)(you)(you)(you)(you)負(fu)趨性(xing)，即(ji)有(you)(you)(you)(you)(you)(you)(you)(you)光(guang)時(shi)(shi)下(xia)沉(chen)水(shui)(shui)(shui)(shui)(shui)底，無光(guang)或(huo)弱(ruo)光(guang)時(shi)(shi)浮向(xiang)水(shui)(shui)(shui)(shui)(shui)面。平(ping)衡囊(nang)在(zai)(zai)水(shui)(shui)(shui)(shui)(shui)螅(xi)水(shui)(shui)(shui)(shui)(shui)母(mu)結(jie)(jie)(jie)構(gou)簡(jian)單，在(zai)(zai)緣(yuan)膜(mo)基(ji)部或(huo)下(xia)傘(san)(san)面神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)環（即(ji)外(wai)(wai)神(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)(shen)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)環）處形(xing)成(cheng)一(yi)(yi)(yi)(yi)個(ge)(ge)(ge)(ge)(ge)小(xiao)(xiao)(xiao)囊(nang)，囊(nang)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)內壁有(you)(you)(you)(you)(you)(you)(you)(you)感(gan)覺(jue)(jue)(jue)細(xi)(xi)胞(bao)(bao)(bao)(bao)，細(xi)(xi)胞(bao)(bao)(bao)(bao)上(shang)也(ye)有(you)(you)(you)(you)(you)(you)(you)(you)纖(xian)毛(mao)。囊(nang)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)底部有(you)(you)(you)(you)(you)(you)(you)(you)一(yi)(yi)(yi)(yi)鈣質結(jie)(jie)(jie)石。它(ta)是(shi)(shi)(shi)(shi)(shi)一(yi)(yi)(yi)(yi)種重力感(gan)受器。當傘(san)(san)緣(yuan)傾斜時(shi)(shi)，結(jie)(jie)(jie)石與感(gan)覺(jue)(jue)(jue)細(xi)(xi)胞(bao)(bao)(bao)(bao)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)纖(xian)毛(mao)接觸(chu)，并刺激纖(xian)毛(mao)細(xi)(xi)胞(bao)(bao)(bao)(bao)以(yi)產生(sheng)動(dong)(dong)(dong)(dong)作電位，抑(yi)制了該(gai)側肌(ji)肉(rou)(rou)纖(xian)維的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)收縮(suo)(suo)，通過肌(ji)肉(rou)(rou)收縮(suo)(suo)再(zai)調(diao)整身體使恢復平(ping)衡位置。缽(bo)水(shui)(shui)(shui)(shui)(shui)母(mu)類(lei)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)平(ping)衡囊(nang)結(jie)(jie)(jie)構(gou)更(geng)復雜，將在(zai)(zai)有(you)(you)(you)(you)(you)(you)(you)(you)關節(jie)中敘(xu)述

生殖與生活史

無(wu)(wu)性生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)及有性生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)在(zai)(zai)(zai)(zai)腔(qiang)腸(chang)(chang)(chang)動物中都(dou)是(shi)很普遍的(de)(de)(de)(de)(de)(de)(de)。無(wu)(wu)性生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)的(de)(de)(de)(de)(de)(de)(de)主(zhu)要形(xing)(xing)式(shi)是(shi)出(chu)(chu)(chu)(chu)芽(ya)生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)，特(te)別是(shi)在(zai)(zai)(zai)(zai)水(shui)(shui)(shui)(shui)(shui)(shui)螅(xi)(xi)(xi)(xi)型(xing)更為(wei)(wei)(wei)常見。例(li)如水(shui)(shui)(shui)(shui)(shui)(shui)螅(xi)(xi)(xi)(xi)出(chu)(chu)(chu)(chu)芽(ya)時從身(shen)體(ti)(ti)(ti)(ti)(ti)(ti)的(de)(de)(de)(de)(de)(de)(de)靠基部通過體(ti)(ti)(ti)(ti)(ti)(ti)壁及胃(wei)(wei)(wei)腔(qiang)的(de)(de)(de)(de)(de)(de)(de)向外突(tu)出(chu)(chu)(chu)(chu)，再(zai)長(chang)出(chu)(chu)(chu)(chu)觸手與口(kou)(kou)即形(xing)(xing)成(cheng)芽(ya)體(ti)(ti)(ti)(ti)(ti)(ti)，以(yi)后芽(ya)體(ti)(ti)(ti)(ti)(ti)(ti)與母(mu)(mu)體(ti)(ti)(ti)(ti)(ti)(ti)分離即形(xing)(xing)成(cheng)新的(de)(de)(de)(de)(de)(de)(de)個體(ti)(ti)(ti)(ti)(ti)(ti)。但(dan)在(zai)(zai)(zai)(zai)藪枝螅(xi)(xi)(xi)(xi)（Obelia）所形(xing)(xing)成(cheng)的(de)(de)(de)(de)(de)(de)(de)芽(ya)體(ti)(ti)(ti)(ti)(ti)(ti)與母(mu)(mu)體(ti)(ti)(ti)(ti)(ti)(ti)不分離則形(xing)(xing)成(cheng)了(le)群體(ti)(ti)(ti)(ti)(ti)(ti)。其次，也可以(yi)通過分裂(lie)方(fang)式(shi)進行無(wu)(wu)性生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)，主(zhu)要發生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)在(zai)(zai)(zai)(zai)水(shui)(shui)(shui)(shui)(shui)(shui)螅(xi)(xi)(xi)(xi)型(xing)，例(li)如海葵可以(yi)縱分裂(lie)，缽水(shui)(shui)(shui)(shui)(shui)(shui)母(mu)(mu)的(de)(de)(de)(de)(de)(de)(de)幼(you)體(ti)(ti)(ti)(ti)(ti)(ti)以(yi)橫分裂(lie)進行無(wu)(wu)性生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)。此外水(shui)(shui)(shui)(shui)(shui)(shui)螅(xi)(xi)(xi)(xi)型(xing)一般具有很強的(de)(de)(de)(de)(de)(de)(de)再(zai)生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)能(neng)力，例(li)如，將水(shui)(shui)(shui)(shui)(shui)(shui)螅(xi)(xi)(xi)(xi)切成(cheng)數(shu)段(duan)(duan)，條件合宜時每段(duan)(duan)都(dou)可以(yi)再(zai)生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)成(cheng)一個新的(de)(de)(de)(de)(de)(de)(de)個體(ti)(ti)(ti)(ti)(ti)(ti)，再(zai)生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)時口(kou)(kou)與反口(kou)(kou)端的(de)(de)(de)(de)(de)(de)(de)極性不變，但(dan)口(kou)(kou)端的(de)(de)(de)(de)(de)(de)(de)再(zai)生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)速度比(bi)反口(kou)(kou)端迅(xun)速。所以(yi)水(shui)(shui)(shui)(shui)(shui)(shui)螅(xi)(xi)(xi)(xi)型(xing)的(de)(de)(de)(de)(de)(de)(de)再(zai)生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)現象也被認(ren)為(wei)(wei)(wei)是(shi)無(wu)(wu)性生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)的(de)(de)(de)(de)(de)(de)(de)一種(zhong)(zhong)方(fang)式(shi)。有些生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)出(chu)(chu)(chu)(chu)現在(zai)(zai)(zai)(zai)多數(shu)水(shui)(shui)(shui)(shui)(shui)(shui)螅(xi)(xi)(xi)(xi)型(xing)及所有的(de)(de)(de)(de)(de)(de)(de)水(shui)(shui)(shui)(shui)(shui)(shui)母(mu)(mu)型(xing)，除(chu)少數(shu)種(zhong)(zhong)類例(li)如水(shui)(shui)(shui)(shui)(shui)(shui)螅(xi)(xi)(xi)(xi)為(wei)(wei)(wei)雌雄同體(ti)(ti)(ti)(ti)(ti)(ti)之(zhi)外，絕大(da)多數(shu)種(zhong)(zhong)類為(wei)(wei)(wei)雌雄異(yi)體(ti)(ti)(ti)(ti)(ti)(ti)（或(huo)異(yi)群體(ti)(ti)(ti)(ti)(ti)(ti)）。生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)細(xi)胞(bao)來(lai)(lai)源于間(jian)細(xi)胞(bao)，然后遷移到(dao)固定的(de)(de)(de)(de)(de)(de)(de)位(wei)(wei)置上(shang)形(xing)(xing)成(cheng)生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)腺(xian)(xian)(xian)。水(shui)(shui)(shui)(shui)(shui)(shui)螅(xi)(xi)(xi)(xi)蟲(chong)綱的(de)(de)(de)(de)(de)(de)(de)動物生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)腺(xian)(xian)(xian)來(lai)(lai)源于表(biao)(biao)(biao)皮(pi)層(ceng)(ceng)，例(li)如水(shui)(shui)(shui)(shui)(shui)(shui)螅(xi)(xi)(xi)(xi)，水(shui)(shui)(shui)(shui)(shui)(shui)螅(xi)(xi)(xi)(xi)水(shui)(shui)(shui)(shui)(shui)(shui)母(mu)(mu)的(de)(de)(de)(de)(de)(de)(de)生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)腺(xian)(xian)(xian)位(wei)(wei)于放(fang)射(she)管下或(huo)垂唇周圍，但(dan)都(dou)是(shi)來(lai)(lai)源于表(biao)(biao)(biao)皮(pi)層(ceng)(ceng)細(xi)胞(bao)。缽水(shui)(shui)(shui)(shui)(shui)(shui)母(mu)(mu)綱的(de)(de)(de)(de)(de)(de)(de)生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)細(xi)胞(bao)起(qi)源于胃(wei)(wei)(wei)層(ceng)(ceng)位(wei)(wei)于胃(wei)(wei)(wei)囊低部。珊(shan)瑚綱的(de)(de)(de)(de)(de)(de)(de)生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)細(xi)胞(bao)是(shi)由胃(wei)(wei)(wei)腔(qiang)中的(de)(de)(de)(de)(de)(de)(de)隔(ge)膜上(shang)發生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)，也是(shi)內胚(pei)層(ceng)(ceng)來(lai)(lai)源。腔(qiang)腸(chang)(chang)(chang)動物只(zhi)有生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)腺(xian)(xian)(xian)，沒有出(chu)(chu)(chu)(chu)現生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)導管及生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)附屬腺(xian)(xian)(xian)，生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)細(xi)胞(bao)成(cheng)熟之(zhi)后由口(kou)(kou)排(pai)出(chu)(chu)(chu)(chu)，或(huo)由體(ti)(ti)(ti)(ti)(ti)(ti)壁破裂(lie)而釋(shi)放(fang)。受精(jing)作用依不同的(de)(de)(de)(de)(de)(de)(de)種(zhong)(zhong)而異(yi)，或(huo)在(zai)(zai)(zai)(zai)體(ti)(ti)(ti)(ti)(ti)(ti)外海水(shui)(shui)(shui)(shui)(shui)(shui)中進行，或(huo)在(zai)(zai)(zai)(zai)垂管的(de)(de)(de)(de)(de)(de)(de)表(biao)(biao)(biao)面，或(huo)在(zai)(zai)(zai)(zai)胃(wei)(wei)(wei)腔(qiang)內生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)腺(xian)(xian)(xian)的(de)(de)(de)(de)(de)(de)(de)部位(wei)(wei)進行。卵裂(lie)是(shi)完(wan)全的(de)(de)(de)(de)(de)(de)(de)，形(xing)(xing)成(cheng)中空的(de)(de)(de)(de)(de)(de)(de)囊胚(pei)，經(jing)移入法或(huo)內陷(xian)法形(xing)(xing)成(cheng)原腸(chang)(chang)(chang)胚(pei)，結果形(xing)(xing)成(cheng)兩層(ceng)(ceng)細(xi)胞(bao)，即兩個胚(pei)層(ceng)(ceng)，內部成(cheng)團(tuan)的(de)(de)(de)(de)(de)(de)(de)細(xi)胞(bao)為(wei)(wei)(wei)內胚(pei)層(ceng)(ceng)，將來(lai)(lai)形(xing)(xing)成(cheng)成(cheng)體(ti)(ti)(ti)(ti)(ti)(ti)的(de)(de)(de)(de)(de)(de)(de)胃(wei)(wei)(wei)層(ceng)(ceng)，外表(biao)(biao)(biao)的(de)(de)(de)(de)(de)(de)(de)一層(ceng)(ceng)為(wei)(wei)(wei)外胚(pei)層(ceng)(ceng)，將來(lai)(lai)形(xing)(xing)成(cheng)成(cheng)體(ti)(ti)(ti)(ti)(ti)(ti)的(de)(de)(de)(de)(de)(de)(de)表(biao)(biao)(biao)皮(pi)層(ceng)(ceng)。實心的(de)(de)(de)(de)(de)(de)(de)原腸(chang)(chang)(chang)胚(pei)迅(xun)速延長(chang)，體(ti)(ti)(ti)(ti)(ti)(ti)表(biao)(biao)(biao)出(chu)(chu)(chu)(chu)現纖毛，形(xing)(xing)成(cheng)了(le)自由游泳的(de)(de)(de)(de)(de)(de)(de)浮浪(lang)(lang)幼(you)蟲(chong)（planula）。浮浪(lang)(lang)幼(you)蟲(chong)早期(qi)沒有口(kou)(kou)及胃(wei)(wei)(wei)腔(qiang)，游泳一段(duan)(duan)時間(jian)之(zhi)后，固著在(zai)(zai)(zai)(zai)水(shui)(shui)(shui)(shui)(shui)(shui)草(cao)、巖石或(huo)其他物體(ti)(ti)(ti)(ti)(ti)(ti)上(shang)發育(yu)成(cheng)水(shui)(shui)(shui)(shui)(shui)(shui)螅(xi)(xi)(xi)(xi)型(xing)體(ti)(ti)(ti)(ti)(ti)(ti)，或(huo)再(zai)經(jing)過出(chu)(chu)(chu)(chu)芽(ya)生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)形(xing)(xing)成(cheng)群體(ti)(ti)(ti)(ti)(ti)(ti)。淡水(shui)(shui)(shui)(shui)(shui)(shui)生(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)(sheng)活的(de)(de)(de)(de)(de)(de)(de)水(shui)(shui)(shui)(shui)(shui)(shui)螅(xi)(xi)(xi)(xi)沒有幼(you)蟲(chong)期(qi)，其受精(jing)卵直接發育(yu)。