刺胞(bao)(bao)動(dong)物(wu)(wu)(wu)門(men)（Cnidaria）又稱刺細胞(bao)(bao)動(dong)物(wu)(wu)(wu)門(men)，過(guo)去稱為(wei)(wei)腔腸(chang)動(dong)物(wu)(wu)(wu)門(men)（Coelenterata），因為(wei)(wei)它的(de)含義適用于(yu)(yu)刺胞(bao)(bao)動(dong)物(wu)(wu)(wu)及櫛(zhi)水(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)母(mu)動(dong)物(wu)(wu)(wu)，所以(yi)現(xian)多(duo)已廢(fei)棄不用。刺胞(bao)(bao)動(dong)物(wu)(wu)(wu)體(ti)呈(cheng)輻射或兩(liang)輻射對稱，僅(jin)具(ju)二(er)胚(pei)層(ceng)(ceng)(ceng)，是最原始的(de)后(hou)(hou)(hou)生(sheng)(sheng)(sheng)動(dong)物(wu)(wu)(wu)。體(ti)壁由(you)外胚(pei)層(ceng)(ceng)(ceng)、內胚(pei)層(ceng)(ceng)(ceng)和中(zhong)膠層(ceng)(ceng)(ceng)組成。內胚(pei)層(ceng)(ceng)(ceng)圍成身體(ti)的(de)整個(ge)內腔稱消(xiao)化循環腔，腔腸(chang)一端為(wei)(wei)口(kou)，他端閉塞，無肛門(men)。體(ti)壁中(zhong)有(you)(you)(you)刺細胞(bao)(bao)。腔腸(chang)動(dong)物(wu)(wu)(wu)的(de)骨骼(ge)主(zhu)要為(wei)(wei)外骨骼(ge)，具(ju)有(you)(you)(you)支(zhi)持(chi)和保護功(gong)能。多(duo)由(you)幾丁質(zhi)(zhi)、角質(zhi)(zhi)和石灰質(zhi)(zhi)構成。在很多(duo)珊(shan)(shan)瑚(hu)蟲(chong)中(zhong)具(ju)有(you)(you)(you)骨針或骨軸(zhou)，它們存在于(yu)(yu)中(zhong)膠層(ceng)(ceng)(ceng)，或突出(chu)(chu)于(yu)(yu)體(ti)表(biao)面(mian)。有(you)(you)(you)無性和有(you)(you)(you)性兩(liang)種(zhong)(zhong)(zhong)生(sheng)(sheng)(sheng)殖方(fang)式，并往往出(chu)(chu)現(xian)在同一種(zhong)(zhong)(zhong)的(de)生(sheng)(sheng)(sheng)活(huo)史(shi)中(zhong)，即水(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)螅(xi)(xi)(xi)型(xing)世代(dai)用無性出(chu)(chu)芽(ya)生(sheng)(sheng)(sheng)殖方(fang)式產(chan)(chan)生(sheng)(sheng)(sheng)水(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)母(mu)型(xing)世代(dai)，而水(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)母(mu)型(xing)個(ge)體(ti)脫離母(mu)體(ti)，長大(da)成熟(shu)以(yi)后(hou)(hou)(hou)，又以(yi)有(you)(you)(you)性生(sheng)(sheng)(sheng)殖方(fang)式產(chan)(chan)生(sheng)(sheng)(sheng)水(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)螅(xi)(xi)(xi)型(xing)個(ge)體(ti)，兩(liang)個(ge)世代(dai)互相(xiang)交替完成整個(ge)生(sheng)(sheng)(sheng)活(huo)史(shi)。約(yue)1萬種(zhong)(zhong)(zhong)，可(ke)分為(wei)(wei)：水(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)螅(xi)(xi)(xi)蟲(chong)綱(gang)(gang)(gang)、缽(bo)(bo)水(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)母(mu)綱(gang)(gang)(gang)和珊(shan)(shan)瑚(hu)蟲(chong)綱(gang)(gang)(gang)3綱(gang)(gang)(gang)，一般(ban)認為(wei)(wei)水(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)螅(xi)(xi)(xi)蟲(chong)綱(gang)(gang)(gang)是最原始的(de)。絕(jue)大(da)部分海(hai)(hai)(hai)產(chan)(chan)，只(zhi)有(you)(you)(you)少數(shu)種(zhong)(zhong)(zhong)類產(chan)(chan)于(yu)(yu)淡水(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)，以(yi)熱帶和亞(ya)熱帶海(hai)(hai)(hai)洋的(de)淺水(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)區(qu)最豐富。較小種(zhong)(zhong)(zhong)類可(ke)作(zuo)魚類食餌，珊(shan)(shan)瑚(hu)骨骼(ge)（如(ru)紅珊(shan)(shan)瑚(hu)）可(ke)作(zuo)工藝品(pin)，古珊(shan)(shan)瑚(hu)和現(xian)代(dai)珊(shan)(shan)瑚(hu)可(ke)形成儲油(you)層(ceng)(ceng)(ceng)，海(hai)(hai)(hai)邊的(de)珊(shan)(shan)瑚(hu)礁可(ke)作(zuo)天然海(hai)(hai)(hai)堤；海(hai)(hai)(hai)蜇(zhe)鹽(yan)漬(zi)后(hou)(hou)(hou)成為(wei)(wei)食品(pin)，有(you)(you)(you)些種(zhong)(zhong)(zhong)類可(ke)作(zuo)藥用；有(you)(you)(you)些浮游水(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)母(mu)類可(ke)作(zuo)為(wei)(wei)海(hai)(hai)(hai)流指示生(sheng)(sheng)(sheng)物(wu)(wu)(wu)；但(dan)是，有(you)(you)(you)些大(da)型(xing)水(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)母(mu)（如(ru)霞水(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)母(mu)、根口(kou)水(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)母(mu)）在大(da)量出(chu)(chu)現(xian)時，會阻塞或破壞漁網(wang)，有(you)(you)(you)的(de)海(hai)(hai)(hai)葵混于(yu)(yu)漁獲物(wu)(wu)(wu)中(zhong)，人(ren)食后(hou)(hou)(hou)中(zhong)毒致死。刺胞(bao)(bao)動(dong)物(wu)(wu)(wu)除極少數(shu)種(zhong)(zhong)(zhong)類為(wei)(wei)淡水(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)生(sheng)(sheng)(sheng)活(huo)外，絕(jue)大(da)多(duo)數(shu)種(zhong)(zhong)(zhong)均為(wei)(wei)海(hai)(hai)(hai)洋生(sheng)(sheng)(sheng)活(huo)，多(duo)數(shu)在淺海(hai)(hai)(hai)，少數(shu)為(wei)(wei)深(shen)海(hai)(hai)(hai)種(zhong)(zhong)(zhong)，現(xian)存約(yue)11000種(zhong)(zhong)(zhong)，分為(wei)(wei)3個(ge)綱(gang)(gang)(gang)：水(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)螅(xi)(xi)(xi)綱(gang)(gang)(gang)（Hydrozoa）、缽(bo)(bo)水(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)(shui)母(mu)綱(gang)(gang)(gang)（Scyphozoa）、珊(shan)(shan)瑚(hu)綱(gang)(gang)(gang)（Anthozoa）。
刺胞動(dong)(dong)物很少能做主(zhu)動(dong)(dong)的(de)(de)移位運(yun)動(dong)(dong)，運(yun)動(dong)(dong)的(de)(de)能力是(shi)(shi)很有(you)(you)(you)限的(de)(de)，特別是(shi)(shi)水(shui)(shui)螅(xi)型。運(yun)動(dong)(dong)是(shi)(shi)由(you)表皮肌肉細(xi)胞中肌原纖(xian)維(wei)(wei)的(de)(de)收(shou)(shou)縮(suo)(suo)(suo)(suo)所引(yin)起。例(li)如(ru)水(shui)(shui)螅(xi)的(de)(de)身(shen)體(ti)(ti)(ti)可做伸縮(suo)(suo)(suo)(suo)運(yun)動(dong)(dong)，伸展時(shi)體(ti)(ti)(ti)長可達15～20mm，收(shou)(shou)縮(suo)(suo)(suo)(suo)時(shi)體(ti)(ti)(ti)長僅(jin)0.5mm，這種伸縮(suo)(suo)(suo)(suo)是(shi)(shi)爆(bao)發式的(de)(de)，每5～10分(fen)(fen)鐘左(zuo)右(you)爆(bao)發一(yi)次，主(zhu)要(yao)是(shi)(shi)由(you)外皮肌細(xi)胞的(de)(de)縱行肌原纖(xian)維(wei)(wei)的(de)(de)收(shou)(shou)縮(suo)(suo)(suo)(suo)所引(yin)起。身(shen)體(ti)(ti)(ti)一(yi)側的(de)(de)肌原纖(xian)維(wei)(wei)的(de)(de)收(shou)(shou)縮(suo)(suo)(suo)(suo)可引(yin)起身(shen)體(ti)(ti)(ti)的(de)(de)彎曲。有(you)(you)(you)時(shi)靠(kao)彎曲身(shen)體(ti)(ti)(ti)及觸手并與基盤的(de)(de)交(jiao)替附著而做翻斛(hu)斗式的(de)(de)運(yun)動(dong)(dong)。基盤處粘細(xi)胞可分(fen)(fen)泌大量的(de)(de)氣泡，可使水(shui)(shui)螅(xi)在水(shui)(shui)面(mian)上(shang)做短暫的(de)(de)漂浮。缽水(shui)(shui)母(mu)類和珊瑚(hu)類的(de)(de)肌原纖(xian)維(wei)(wei)已與表皮細(xi)胞分(fen)(fen)離形成獨(du)立的(de)(de)一(yi)層(ceng)(ceng)肌纖(xian)維(wei)(wei)，例(li)如(ru)水(shui)(shui)母(mu)的(de)(de)肌原纖(xian)維(wei)(wei)在下傘面(mian)及傘緣形成薄薄的(de)(de)一(yi)層(ceng)(ceng)肌肉環，有(you)(you)(you)的(de)(de)被輻(fu)管(guan)分(fen)(fen)離成片(pian)狀(zhuang)，其纖(xian)維(wei)(wei)有(you)(you)(you)橫紋，它們做有(you)(you)(you)規(gui)律的(de)(de)收(shou)(shou)縮(suo)(suo)(suo)(suo)，使傘面(mian)有(you)(you)(you)節奏(zou)的(de)(de)收(shou)(shou)縮(suo)(suo)(suo)(suo)運(yun)動(dong)(dong)。當(dang)傘緣收(shou)(shou)縮(suo)(suo)(suo)(suo)時(shi)，傘緣內的(de)(de)水(shui)(shui)被噴出，由(you)于反作用力而推(tui)動(dong)(dong)水(shui)(shui)母(mu)體(ti)(ti)(ti)向(xiang)上(shang)運(yun)動(dong)(dong)，當(dang)傘及傘緣肌肉舒張，被壓縮(suo)(suo)(suo)(suo)的(de)(de)中膠(jiao)層(ceng)(ceng)的(de)(de)彈性，使傘又恢復了原形，水(shui)(shui)又重新進入傘緣內，身(shen)體(ti)(ti)(ti)下沉(chen)(chen)，但(dan)由(you)于收(shou)(shou)縮(suo)(suo)(suo)(suo)比舒張要(yao)快，所以(yi)水(shui)(shui)母(mu)還是(shi)(shi)可以(yi)向(xiang)上(shang)垂直運(yun)動(dong)(dong)。水(shui)(shui)母(mu)類的(de)(de)垂直運(yun)動(dong)(dong)在有(you)(you)(you)緣膜(mo)(mo)的(de)(de)水(shui)(shui)母(mu)可以(yi)看的(de)(de)更為清楚。一(yi)旦肌肉停止收(shou)(shou)縮(suo)(suo)(suo)(suo)，水(shui)(shui)母(mu)就會自(zi)然下沉(chen)(chen)。其水(shui)(shui)平方(fang)向(xiang)的(de)(de)運(yun)動(dong)(dong)多是(shi)(shi)被動(dong)(dong)的(de)(de)，多是(shi)(shi)由(you)于水(shui)(shui)流及風力所推(tui)動(dong)(dong)。又例(li)如(ru)在珊瑚(hu)類，海葵(kui)的(de)(de)肌原纖(xian)維(wei)(wei)在隔膜(mo)(mo)上(shang)形成發達的(de)(de)牽縮(suo)(suo)(suo)(suo)肌，它的(de)(de)收(shou)(shou)縮(suo)(suo)(suo)(suo)非常有(you)(you)(you)力，所以(yi)當(dang)海葵(kui)固著在巖石上(shang)是(shi)(shi)很難將它取下的(de)(de)。
刺(ci)胞(bao)動(dong)(dong)物(wu)(wu)(wu)(wu)都是(shi)(shi)(shi)肉(rou)食(shi)(shi)(shi)性的(de)(de)，以浮游生(sheng)(sheng)物(wu)(wu)(wu)(wu)，小(xiao)的(de)(de)甲(jia)殼類(lei)(lei)、多(duo)(duo)毛類(lei)(lei)甚至小(xiao)的(de)(de)魚類(lei)(lei)為食(shi)(shi)(shi)。由(you)于(yu)食(shi)(shi)(shi)物(wu)(wu)(wu)(wu)的(de)(de)機(ji)械刺(ci)激(ji)和化學刺(ci)激(ji)，引起水螅類(lei)(lei)動(dong)(dong)物(wu)(wu)(wu)(wu)伸長觸手，并放出刺(ci)絲囊以纏(chan)繞、麻(ma)痹、毒殺(sha)捕獲物(wu)(wu)(wu)(wu)，再(zai)將食(shi)(shi)(shi)物(wu)(wu)(wu)(wu)送(song)入(ru)口(kou)中。口(kou)區腺(xian)(xian)細(xi)(xi)(xi)胞(bao)分泌的(de)(de)粘(zhan)液有(you)(you)利于(yu)食(shi)(shi)(shi)物(wu)(wu)(wu)(wu)的(de)(de)吞(tun)咽，食(shi)(shi)(shi)物(wu)(wu)(wu)(wu)進入(ru)胃(wei)(wei)(wei)腔(qiang)(qiang)后(hou)(hou)，胃(wei)(wei)(wei)層的(de)(de)腺(xian)(xian)細(xi)(xi)(xi)胞(bao)開(kai)始(shi)分泌蛋(dan)白酶(mei)，分解、消化食(shi)(shi)(shi)物(wu)(wu)(wu)(wu)使(shi)之(zhi)形成(cheng)許(xu)多(duo)(duo)多(duo)(duo)肽，同時在(zai)胃(wei)(wei)(wei)腔(qiang)(qiang)中由(you)于(yu)營(ying)(ying)養肌(ji)肉(rou)細(xi)(xi)(xi)胞(bao)的(de)(de)鞭毛運(yun)動(dong)(dong)，食(shi)(shi)(shi)物(wu)(wu)(wu)(wu)得以混合與推動(dong)(dong)。經這種(zhong)細(xi)(xi)(xi)胞(bao)外(wai)消化之(zhi)后(hou)(hou)，開(kai)始(shi)細(xi)(xi)(xi)胞(bao)內(nei)的(de)(de)消化過(guo)程，營(ying)(ying)養肌(ji)肉(rou)細(xi)(xi)(xi)胞(bao)的(de)(de)偽(wei)足吞(tun)噬食(shi)(shi)(shi)物(wu)(wu)(wu)(wu)顆粒，在(zai)細(xi)(xi)(xi)胞(bao)內(nei)形成(cheng)大(da)量的(de)(de)食(shi)(shi)(shi)物(wu)(wu)(wu)(wu)泡(pao)，經過(guo)酸(suan)性及(ji)堿(jian)性的(de)(de)化學過(guo)程之(zhi)后(hou)(hou)，營(ying)(ying)養物(wu)(wu)(wu)(wu)質由(you)細(xi)(xi)(xi)胞(bao)的(de)(de)擴(kuo)散作用(yong)輸(shu)送(song)到全身。缽水母(mu)類(lei)(lei)及(ji)珊瑚類(lei)(lei)胃(wei)(wei)(wei)腔(qiang)(qiang)結構(gou)比較復雜。缽水母(mu)的(de)(de)胃(wei)(wei)(wei)腔(qiang)(qiang)中有(you)(you)各種(zhong)輻管(guan)(guan)及(ji)環管(guan)(guan)，胃(wei)(wei)(wei)囊中有(you)(you)內(nei)胚(pei)層起源的(de)(de)胃(wei)(wei)(wei)絲；珊瑚類(lei)(lei)的(de)(de)胃(wei)(wei)(wei)腔(qiang)(qiang)被許(xu)多(duo)(duo)隔膜(mo)分隔成(cheng)許(xu)多(duo)(duo)小(xiao)室，隔膜(mo)上(shang)有(you)(you)隔膜(mo)絲。胃(wei)(wei)(wei)絲及(ji)隔膜(mo)絲中含有(you)(you)大(da)量的(de)(de)刺(ci)細(xi)(xi)(xi)胞(bao)及(ji)腺(xian)(xian)細(xi)(xi)(xi)胞(bao)，它們是(shi)(shi)(shi)將食(shi)(shi)(shi)物(wu)(wu)(wu)(wu)吞(tun)入(ru)胃(wei)(wei)(wei)腔(qiang)(qiang)之(zhi)后(hou)(hou)才殺(sha)死及(ji)消化。消化后(hou)(hou)的(de)(de)營(ying)(ying)養物(wu)(wu)(wu)(wu)通過(guo)各種(zhong)管(guan)(guan)道輸(shu)送(song)到全身，未消化的(de)(de)食(shi)(shi)(shi)物(wu)(wu)(wu)(wu)殘渣仍由(you)口(kou)排出。糖(tang)元(yuan)及(ji)脂肪是(shi)(shi)(shi)腔(qiang)(qiang)腸動(dong)(dong)物(wu)(wu)(wu)(wu)的(de)(de)主要貯(zhu)存物(wu)(wu)(wu)(wu)。刺(ci)胞(bao)動(dong)(dong)物(wu)(wu)(wu)(wu)中許(xu)多(duo)(duo)種(zhong)類(lei)(lei)，特(te)別是(shi)(shi)(shi)海洋中的(de)(de)造礁珊瑚類(lei)(lei)，體內(nei)均有(you)(you)共生(sheng)(sheng)的(de)(de)藻(zao)類(lei)(lei)，如動(dong)(dong)物(wu)(wu)(wu)(wu)黃藻(zao)、腰(yao)鞭毛藻(zao)之(zhi)類(lei)(lei)。藻(zao)類(lei)(lei)能進行光合作用(yong)，產生(sheng)(sheng)甘油、脂肪、糖(tang)及(ji)脯氨酸(suan)等，并提供給刺(ci)胞(bao)動(dong)(dong)物(wu)(wu)(wu)(wu)作為其(qi)補充營(ying)(ying)養。這將在(zai)珊瑚綱(gang)中做進一步(bu)的(de)(de)敘述。
刺胞(bao)(bao)動(dong)物(wu)(wu)沒有專門(men)的呼吸及排(pai)(pai)泄器官(guan)，由(you)于身體是(shi)由(you)兩(liang)層(ceng)細胞(bao)(bao)圍繞胃循環腔所(suo)(suo)組(zu)成(cheng)，并(bing)通(tong)(tong)過(guo)口使胃腔與外(wai)界相通(tong)(tong)，實際上體壁的兩(liang)層(ceng)細胞(bao)(bao)均與外(wai)界環境接觸，所(suo)(suo)以(yi)呼吸與排(pai)(pai)泄作(zuo)用可以(yi)由(you)體壁細胞(bao)(bao)直接獨立進行。出、入(ru)(ru)口及胃腔的水流可以(yi)攜帶(dai)入(ru)(ru)新(xin)鮮的氧(yang)氣，并(bing)帶(dai)走代謝產物(wu)(wu)。刺胞(bao)(bao)動(dong)物(wu)(wu)的主要含(han)氮廢物(wu)(wu)是(shi)氨。
刺(ci)(ci)(ci)胞(bao)(bao)(bao)(bao)(bao)(bao)(bao)動(dong)物(wu)(wu)(wu)是(shi)(shi)(shi)(shi)(shi)(shi)最早出現(xian)(xian)神(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)構(gou)(gou)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)多(duo)細(xi)(xi)(xi)(xi)(xi)胞(bao)(bao)(bao)(bao)(bao)(bao)(bao)動(dong)物(wu)(wu)(wu)。神(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)構(gou)(gou)原(yuan)(yuan)始(shi)，是(shi)(shi)(shi)(shi)(shi)(shi)由(you)(you)(you)雙極(ji)(ji)神(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)極(ji)(ji)神(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(ji)(ji)神(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)(xian)維聯(lian)合成(cheng)(cheng)(cheng)(cheng)神(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)(huo)(huo)神(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)(yi)般(ban)位(wei)于(yu)外(wai)(wai)表(biao)(biao)皮(pi)細(xi)(xi)(xi)(xi)(xi)胞(bao)(bao)(bao)(bao)(bao)(bao)(bao)基部(bu)肌肉層之(zhi)外(wai)(wai)，呈網(wang)(wang)(wang)狀(zhuang)分(fen)(fen)布(bu)，故(gu)稱(cheng)網(wang)(wang)(wang)狀(zhuang)神(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)(xi)統（netnervous system）。由(you)(you)(you)于(yu)神(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)(xi)(xi)(xi)胞(bao)(bao)(bao)(bao)(bao)(bao)(bao)可(ke)向各個(ge)(ge)(ge)(ge)(ge)(ge)(ge)方(fang)向傳(chuan)(chuan)(chuan)導(dao)(dao)，也(ye)(ye)稱(cheng)為(wei)漫散(san)神(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)(xi)統（diffusenervous system）。水(shui)(shui)(shui)(shui)(shui)(shui)螅就(jiu)只有(you)(you)(you)(you)一(yi)(yi)(yi)(yi)(yi)個(ge)(ge)(ge)(ge)(ge)(ge)(ge)神(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)，但大多(duo)數(shu)腔(qiang)腸動(dong)物(wu)(wu)(wu)除(chu)(chu)了(le)(le)(le)表(biao)(biao)皮(pi)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)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)網(wang)(wang)(wang)之(zhi)外(wai)(wai)，在(zai)胃層的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)基部(bu)也(ye)(ye)有(you)(you)(you)(you)一(yi)(yi)(yi)(yi)(yi)個(ge)(ge)(ge)(ge)(ge)(ge)(ge)神(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)，這兩(liang)(liang)個(ge)(ge)(ge)(ge)(ge)(ge)(ge)神(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)(huo)(huo)是(shi)(shi)(shi)(shi)(shi)(shi)完(wan)全獨立的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)，或(huo)(huo)(huo)有(you)(you)(you)(you)纖(xian)(xian)維相(xiang)聯(lian)。1971年(nian)Westfall等首先證(zheng)明(ming)了(le)(le)(le)水(shui)(shui)(shui)(shui)(shui)(shui)螅及(ji)(ji)其他(ta)腔(qiang)腸動(dong)物(wu)(wu)(wu)在(zai)神(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)間(jian)、神(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(yu)(yu)效應(ying)器(qi)(qi)（表(biao)(biao)皮(pi)肌肉細(xi)(xi)(xi)(xi)(xi)胞(bao)(bao)(bao)(bao)(bao)(bao)(bao)、刺(ci)(ci)(ci)細(xi)(xi)(xi)(xi)(xi)胞(bao)(bao)(bao)(bao)(bao)(bao)(bao)、腺細(xi)(xi)(xi)(xi)(xi)胞(bao)(bao)(bao)(bao)(bao)(bao)(bao)等）之(zhi)間(jian)也(ye)(ye)存在(zai)著(zhu)突(tu)(tu)觸(chu)(chu)傳(chuan)(chuan)(chuan)遞(di)（synaptic transmission）。即(ji)神(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)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)傳(chuan)(chuan)(chuan)導(dao)(dao)是(shi)(shi)(shi)(shi)(shi)(shi)由(you)(you)(you)一(yi)(yi)(yi)(yi)(yi)個(ge)(ge)(ge)(ge)(ge)(ge)(ge)神(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)，傳(chuan)(chuan)(chuan)遞(di)給(gei)另一(yi)(yi)(yi)(yi)(yi)個(ge)(ge)(ge)(ge)(ge)(ge)(ge)神(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)。軸突(tu)(tu)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)末(mo)端具(ju)有(you)(you)(you)(you)突(tu)(tu)觸(chu)(chu)小(xiao)泡（synaptic vesicle），樹突(tu)(tu)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)末(mo)端沒有(you)(you)(you)(you)。傳(chuan)(chuan)(chuan)導(dao)(dao)時(shi)，突(tu)(tu)觸(chu)(chu)小(xiao)泡釋放(fang)乙(yi)酰膽(dan)堿引(yin)起(qi)(qi)后一(yi)(yi)(yi)(yi)(yi)個(ge)(ge)(ge)(ge)(ge)(ge)(ge)神(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(fen)，沖(chong)動(dong)傳(chuan)(chuan)(chuan)出以(yi)(yi)后，乙(yi)酰膽(dan)堿被(bei)神(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)(biao)面(mian)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)膽(dan)堿酯酶水(shui)(shui)(shui)(shui)(shui)(shui)解成(cheng)(cheng)(cheng)(cheng)膽(dan)堿及(ji)(ji)乙(yi)酸而解除(chu)(chu)了(le)(le)(le)激活作(zuo)用。以(yi)(yi)后又發(fa)(fa)(fa)現(xian)(xian)腔(qiang)腸動(dong)物(wu)(wu)(wu)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)突(tu)(tu)觸(chu)(chu)傳(chuan)(chuan)(chuan)導(dao)(dao)分(fen)(fen)為(wei)兩(liang)(liang)種類型(xing)(xing)(xing)。一(yi)(yi)(yi)(yi)(yi)類突(tu)(tu)觸(chu)(chu)是(shi)(shi)(shi)(shi)(shi)(shi)對(dui)稱(cheng)性(xing)(xing)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)傳(chuan)(chuan)(chuan)導(dao)(dao)（symmetrical），即(ji)兩(liang)(liang)個(ge)(ge)(ge)(ge)(ge)(ge)(ge)或(huo)(huo)(huo)多(duo)個(ge)(ge)(ge)(ge)(ge)(ge)(ge)神(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)突(tu)(tu)觸(chu)(chu)小(xiao)泡，因此(ci)沖(chong)動(dong)可(ke)以(yi)(yi)同(tong)時(shi)向兩(liang)(liang)個(ge)(ge)(ge)(ge)(ge)(ge)(ge)或(huo)(huo)(huo)幾個(ge)(ge)(ge)(ge)(ge)(ge)(ge)方(fang)向傳(chuan)(chuan)(chuan)遞(di)，這種傳(chuan)(chuan)(chuan)導(dao)(dao)也(ye)(ye)叫非極(ji)(ji)性(xing)(xing)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)傳(chuan)(chuan)(chuan)導(dao)(dao)（nonpolarized transmission）；另一(yi)(yi)(yi)(yi)(yi)類突(tu)(tu)觸(chu)(chu)是(shi)(shi)(shi)(shi)(shi)(shi)不對(dui)稱(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)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)細(xi)(xi)(xi)(xi)(xi)胞(bao)(bao)(bao)(bao)(bao)(bao)(bao)只有(you)(you)(you)(you)一(yi)(yi)(yi)(yi)(yi)個(ge)(ge)(ge)(ge)(ge)(ge)(ge)末(mo)端具(ju)突(tu)(tu)觸(chu)(chu)小(xiao)泡，神(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)只能(neng)(neng)向一(yi)(yi)(yi)(yi)(yi)個(ge)(ge)(ge)(ge)(ge)(ge)(ge)方(fang)向傳(chuan)(chuan)(chuan)導(dao)(dao)，因此(ci)也(ye)(ye)稱(cheng)為(wei)有(you)(you)(you)(you)極(ji)(ji)性(xing)(xing)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)傳(chuan)(chuan)(chuan)導(dao)(dao)（polarized transmission）。最近的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)研(yan)(yan)究(jiu)證(zheng)明(ming)刺(ci)(ci)(ci)胞(bao)(bao)(bao)(bao)(bao)(bao)(bao)動(dong)物(wu)(wu)(wu)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)非極(ji)(ji)性(xing)(xing)傳(chuan)(chuan)(chuan)導(dao)(dao)是(shi)(shi)(shi)(shi)(shi)(shi)很普遍的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)。也(ye)(ye)有(you)(you)(you)(you)人(ren)認(ren)為(wei)刺(ci)(ci)(ci)胞(bao)(bao)(bao)(bao)(bao)(bao)(bao)動(dong)物(wu)(wu)(wu)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)兩(liang)(liang)個(ge)(ge)(ge)(ge)(ge)(ge)(ge)神(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)(yi)個(ge)(ge)(ge)(ge)(ge)(ge)(ge)是(shi)(shi)(shi)(shi)(shi)(shi)由(you)(you)(you)多(duo)極(ji)(ji)神(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)形成(cheng)(cheng)(cheng)(cheng)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)非極(ji)(ji)性(xing)(xing)傳(chuan)(chuan)(chuan)導(dao)(dao)，也(ye)(ye)就(jiu)是(shi)(shi)(shi)(shi)(shi)(shi)慢傳(chuan)(chuan)(chuan)導(dao)(dao)系(xi)(xi)統；另一(yi)(yi)(yi)(yi)(yi)個(ge)(ge)(ge)(ge)(ge)(ge)(ge)是(shi)(shi)(shi)(shi)(shi)(shi)由(you)(you)(you)雙極(ji)(ji)神(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)形成(cheng)(cheng)(cheng)(cheng)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)極(ji)(ji)性(xing)(xing)傳(chuan)(chuan)(chuan)導(dao)(dao)，也(ye)(ye)就(jiu)是(shi)(shi)(shi)(shi)(shi)(shi)快傳(chuan)(chuan)(chuan)導(dao)(dao)系(xi)(xi)統。刺(ci)(ci)(ci)胞(bao)(bao)(bao)(bao)(bao)(bao)(bao)動(dong)物(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)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)元(yuan)(yuan)(yuan)(yuan)可(ke)以(yi)(yi)有(you)(you)(you)(you)2個(ge)(ge)(ge)(ge)(ge)(ge)(ge)、3個(ge)(ge)(ge)(ge)(ge)(ge)(ge)或(huo)(huo)(huo)多(duo)個(ge)(ge)(ge)(ge)(ge)(ge)(ge)長(chang)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)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)突(tu)(tu)起(qi)(qi)，這些突(tu)(tu)起(qi)(qi)或(huo)(huo)(huo)與(yu)(yu)感(gan)(gan)(gan)(gan)官(guan)(guan)(guan)相(xiang)聯(lian)、或(huo)(huo)(huo)與(yu)(yu)效應(ying)器(qi)(qi)相(xiang)聯(lian)、或(huo)(huo)(huo)與(yu)(yu)其他(ta)神(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)、或(huo)(huo)(huo)者是(shi)(shi)(shi)(shi)(shi)(shi)同(tong)一(yi)(yi)(yi)(yi)(yi)個(ge)(ge)(ge)(ge)(ge)(ge)(ge)神(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)與(yu)(yu)感(gan)(gan)(gan)(gan)官(guan)(guan)(guan)與(yu)(yu)效應(ying)器(qi)(qi)相(xiang)聯(lian)，這種多(duo)樣性(xing)(xing)說明(ming)了(le)(le)(le)神(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)(xi)(xi)(xi)胞(bao)(bao)(bao)(bao)(bao)(bao)(bao)傳(chuan)(chuan)(chuan)導(dao)(dao)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)原(yuan)(yuan)始(shi)性(xing)(xing)。在(zai)生(sheng)理意義上代表(biao)(biao)了(le)(le)(le)高(gao)等動(dong)物(wu)(wu)(wu)所具(ju)有(you)(you)(you)(you)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)感(gan)(gan)(gan)(gan)覺(jue)神(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)神(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(ji)(ji)中樞神(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)(qi)始(shi)階段。此(ci)外(wai)(wai)，刺(ci)(ci)(ci)胞(bao)(bao)(bao)(bao)(bao)(bao)(bao)動(dong)物(wu)(wu)(wu)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)非神(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)，即(ji)上皮(pi)傳(chuan)(chuan)(chuan)導(dao)(dao)也(ye)(ye)是(shi)(shi)(shi)(shi)(shi)(shi)很常(chang)見的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)，例如(ru)刺(ci)(ci)(ci)細(xi)(xi)(xi)(xi)(xi)胞(bao)(bao)(bao)(bao)(bao)(bao)(bao)、表(biao)(biao)皮(pi)肌肉細(xi)(xi)(xi)(xi)(xi)胞(bao)(bao)(bao)(bao)(bao)(bao)(bao)可(ke)以(yi)(yi)完(wan)全獨立于(yu)神(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)而被(bei)自身所控制。水(shui)(shui)(shui)(shui)(shui)(shui)母(mu)(mu)型(xing)(xing)(xing)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)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)結(jie)構(gou)(gou)比水(shui)(shui)(shui)(shui)(shui)(shui)螅型(xing)(xing)(xing)復(fu)雜，例如(ru)水(shui)(shui)(shui)(shui)(shui)(shui)螅水(shui)(shui)(shui)(shui)(shui)(shui)母(mu)(mu)，除(chu)(chu)了(le)(le)(le)傘部(bu)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)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)網(wang)(wang)(wang)之(zhi)外(wai)(wai)，傘緣(yuan)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)上皮(pi)神(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)(xi)(xi)(xi)胞(bao)(bao)(bao)(bao)(bao)(bao)(bao)分(fen)(fen)別在(zai)傘緣(yuan)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)上、下(xia)(xia)面(mian)集(ji)中形成(cheng)(cheng)(cheng)(cheng)兩(liang)(liang)個(ge)(ge)(ge)(ge)(ge)(ge)(ge)神(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(huan)(huan)。下(xia)(xia)面(mian)（或(huo)(huo)(huo)稱(cheng)外(wai)(wai)面(mian)）的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)一(yi)(yi)(yi)(yi)(yi)個(ge)(ge)(ge)(ge)(ge)(ge)(ge)神(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(huan)(huan)更發(fa)(fa)(fa)達(da)。缽(bo)(bo)水(shui)(shui)(shui)(shui)(shui)(shui)母(mu)(mu)類的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)水(shui)(shui)(shui)(shui)(shui)(shui)母(mu)(mu)型(xing)(xing)(xing)多(duo)數(shu)沒有(you)(you)(you)(you)這種神(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(huan)(huan)，而是(shi)(shi)(shi)(shi)(shi)(shi)在(zai)傘緣(yuan)集(ji)中形成(cheng)(cheng)(cheng)(cheng)4～8個(ge)(ge)(ge)(ge)(ge)(ge)(ge)神(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)(shui)母(mu)(mu)型(xing)(xing)(xing)個(ge)(ge)(ge)(ge)(ge)(ge)(ge)體均能(neng)(neng)表(biao)(biao)現(xian)(xian)出一(yi)(yi)(yi)(yi)(yi)種有(you)(you)(you)(you)節(jie)奏(zou)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)收(shou)(shou)縮(suo)運動(dong)，這是(shi)(shi)(shi)(shi)(shi)(shi)由(you)(you)(you)于(yu)水(shui)(shui)(shui)(shui)(shui)(shui)母(mu)(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)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)結(jie)構(gou)(gou)每隔一(yi)(yi)(yi)(yi)(yi)定(ding)時(shi)間(jian)能(neng)(neng)自發(fa)(fa)(fa)地(di)產(chan)生(sheng)動(dong)作(zuo)電(dian)位(wei)，并(bing)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)過(guo)神(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)引(yin)起(qi)(qi)整(zheng)個(ge)(ge)(ge)(ge)(ge)(ge)(ge)身體的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)收(shou)(shou)縮(suo)。研(yan)(yan)究(jiu)已(yi)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)證(zheng)明(ming)這種自發(fa)(fa)(fa)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)動(dong)作(zuo)電(dian)位(wei)是(shi)(shi)(shi)(shi)(shi)(shi)由(you)(you)(you)起(qi)(qi)博點(dian)(dian)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)經(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)(jing)元(yuan)(yuan)(yuan)(yuan)所引(yin)起(qi)(qi)。起(qi)(qi)博點(dian)(dian)神(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)水(shui)(shui)(shui)(shui)(shui)(shui)螅水(shui)(shui)(shui)(shui)(shui)(shui)母(mu)(mu)存在(zai)于(yu)外(wai)(wai)神(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(huan)(huan)中，在(zai)缽(bo)(bo)水(shui)(shui)(shui)(shui)(shui)(shui)母(mu)(mu)類存在(zai)于(yu)感(gan)(gan)(gan)(gan)官(guan)(guan)(guan)神(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。而且每一(yi)(yi)(yi)(yi)(yi)個(ge)(ge)(ge)(ge)(ge)(ge)(ge)神(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)(yi)般(ban)4～8個(ge)(ge)(ge)(ge)(ge)(ge)(ge)）都(dou)有(you)(you)(you)(you)起(qi)(qi)博神(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)(shi)水(shui)(shui)(shui)(shui)(shui)(shui)母(mu)(mu)類有(you)(you)(you)(you)節(jie)奏(zou)博動(dong)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)中心。一(yi)(yi)(yi)(yi)(yi)個(ge)(ge)(ge)(ge)(ge)(ge)(ge)水(shui)(shui)(shui)(shui)(shui)(shui)母(mu)(mu)體似乎有(you)(you)(you)(you)一(yi)(yi)(yi)(yi)(yi)個(ge)(ge)(ge)(ge)(ge)(ge)(ge)起(qi)(qi)博點(dian)(dian)就(jiu)足以(yi)(yi)引(yin)起(qi)(qi)身體有(you)(you)(you)(you)節(jie)奏(zou)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)收(shou)(shou)縮(suo)運動(dong)，但實驗證(zheng)明(ming)多(duo)個(ge)(ge)(ge)(ge)(ge)(ge)(ge)起(qi)(qi)博點(dian)(dian)比僅有(you)(you)(you)(you)一(yi)(yi)(yi)(yi)(yi)個(ge)(ge)(ge)(ge)(ge)(ge)(ge)起(qi)(qi)博點(dian)(dian)能(neng)(neng)使收(shou)(shou)縮(suo)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)節(jie)奏(zou)更有(you)(you)(you)(you)規(gui)律、更有(you)(you)(you)(you)保障、使間(jian)隔的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)時(shi)間(jian)也(ye)(ye)較(jiao)短。腔(qiang)腸動(dong)物(wu)(wu)(wu)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)水(shui)(shui)(shui)(shui)(shui)(shui)螅型(xing)(xing)(xing)體沒有(you)(you)(you)(you)明(ming)顯的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)感(gan)(gan)(gan)(gan)官(guan)(guan)(guan)，其感(gan)(gan)(gan)(gan)覺(jue)細(xi)(xi)(xi)(xi)(xi)胞(bao)(bao)(bao)(bao)(bao)(bao)(bao)可(ke)分(fen)(fen)布(bu)全身，但觸(chu)(chu)手(shou)、口區較(jiao)為(wei)豐富(fu)。水(shui)(shui)(shui)(shui)(shui)(shui)母(mu)(mu)型(xing)(xing)(xing)個(ge)(ge)(ge)(ge)(ge)(ge)(ge)體，在(zai)傘緣(yuan)具(ju)有(you)(you)(you)(you)豐富(fu)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)感(gan)(gan)(gan)(gan)覺(jue)細(xi)(xi)(xi)(xi)(xi)胞(bao)(bao)(bao)(bao)(bao)(bao)(bao)或(huo)(huo)(huo)感(gan)(gan)(gan)(gan)覺(jue)器(qi)(qi)官(guan)(guan)(guan)。感(gan)(gan)(gan)(gan)覺(jue)細(xi)(xi)(xi)(xi)(xi)胞(bao)(bao)(bao)(bao)(bao)(bao)(bao)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)細(xi)(xi)(xi)(xi)(xi)胞(bao)(bao)(bao)(bao)(bao)(bao)(bao)體都(dou)是(shi)(shi)(shi)(shi)(shi)(shi)具(ju)纖(xian)(xian)毛(mao)(mao)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)。感(gan)(gan)(gan)(gan)覺(jue)器(qi)(qi)官(guan)(guan)(guan)包括眼點(dian)(dian)及(ji)(ji)平衡囊。眼點(dian)(dian)是(shi)(shi)(shi)(shi)(shi)(shi)由(you)(you)(you)感(gan)(gan)(gan)(gan)覺(jue)細(xi)(xi)(xi)(xi)(xi)胞(bao)(bao)(bao)(bao)(bao)(bao)(bao)構(gou)(gou)成(cheng)(cheng)(cheng)(cheng)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)杯狀(zhuang)物(wu)(wu)(wu)，內(nei)有(you)(you)(you)(you)色素顆粒(li)分(fen)(fen)布(bu)，它(ta)對(dui)光線或(huo)(huo)(huo)有(you)(you)(you)(you)正趨性(xing)(xing)，即(ji)有(you)(you)(you)(you)光時(shi)游向水(shui)(shui)(shui)(shui)(shui)(shui)面(mian)。或(huo)(huo)(huo)對(dui)光有(you)(you)(you)(you)負趨性(xing)(xing)，即(ji)有(you)(you)(you)(you)光時(shi)下(xia)(xia)沉水(shui)(shui)(shui)(shui)(shui)(shui)底，無光或(huo)(huo)(huo)弱(ruo)光時(shi)浮向水(shui)(shui)(shui)(shui)(shui)(shui)面(mian)。平衡囊在(zai)水(shui)(shui)(shui)(shui)(shui)(shui)螅水(shui)(shui)(shui)(shui)(shui)(shui)母(mu)(mu)結(jie)構(gou)(gou)簡單，在(zai)緣(yuan)膜(mo)基部(bu)或(huo)(huo)(huo)下(xia)(xia)傘面(mian)神(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(huan)(huan)（即(ji)外(wai)(wai)神(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(huan)(huan)）處(chu)形成(cheng)(cheng)(cheng)(cheng)一(yi)(yi)(yi)(yi)(yi)個(ge)(ge)(ge)(ge)(ge)(ge)(ge)小(xiao)囊，囊的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)內(nei)壁有(you)(you)(you)(you)感(gan)(gan)(gan)(gan)覺(jue)細(xi)(xi)(xi)(xi)(xi)胞(bao)(bao)(bao)(bao)(bao)(bao)(bao)，細(xi)(xi)(xi)(xi)(xi)胞(bao)(bao)(bao)(bao)(bao)(bao)(bao)上也(ye)(ye)有(you)(you)(you)(you)纖(xian)(xian)毛(mao)(mao)。囊的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)底部(bu)有(you)(you)(you)(you)一(yi)(yi)(yi)(yi)(yi)鈣(gai)質結(jie)石。它(ta)是(shi)(shi)(shi)(shi)(shi)(shi)一(yi)(yi)(yi)(yi)(yi)種重力感(gan)(gan)(gan)(gan)受(shou)器(qi)(qi)。當(dang)傘緣(yuan)傾斜時(shi)，結(jie)石與(yu)(yu)感(gan)(gan)(gan)(gan)覺(jue)細(xi)(xi)(xi)(xi)(xi)胞(bao)(bao)(bao)(bao)(bao)(bao)(bao)的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)纖(xian)(xian)毛(mao)(mao)接觸(chu)(chu)，并(bing)刺(ci)(ci)(ci)激纖(xian)(xian)毛(mao)(mao)細(xi)(xi)(xi)(xi)(xi)胞(bao)(bao)(bao)(bao)(bao)(bao)(bao)以(yi)(yi)產(chan)生(sheng)動(dong)作(zuo)電(dian)位(wei)，抑制了(le)(le)(le)該側肌肉纖(xian)(xian)維的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)收(shou)(shou)縮(suo)，通過(guo)肌肉收(shou)(shou)縮(suo)再調整(zheng)身體使恢復(fu)平衡位(wei)置(zhi)。缽(bo)(bo)水(shui)(shui)(shui)(shui)(shui)(shui)母(mu)(mu)類的(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)(de)平衡囊結(jie)構(gou)(gou)更復(fu)雜，將(jiang)在(zai)有(you)(you)(you)(you)關(guan)節(jie)中敘(xu)述
無性(xing)生(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)(zhi)(zhi)(zhi)及(ji)有(you)性(xing)生(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)(zhi)(zhi)(zhi)在(zai)(zai)腔(qiang)腸動物(wu)中都(dou)是(shi)(shi)(shi)很普遍的(de)(de)(de)(de)。無性(xing)生(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)(zhi)(zhi)(zhi)的(de)(de)(de)(de)主要形(xing)(xing)(xing)(xing)(xing)式是(shi)(shi)(shi)出(chu)(chu)芽(ya)生(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)(zhi)(zhi)(zhi)，特別是(shi)(shi)(shi)在(zai)(zai)水(shui)(shui)(shui)(shui)螅(xi)(xi)型(xing)(xing)更為(wei)(wei)常見。例(li)如(ru)水(shui)(shui)(shui)(shui)螅(xi)(xi)出(chu)(chu)芽(ya)時(shi)從身體(ti)(ti)(ti)(ti)(ti)(ti)(ti)的(de)(de)(de)(de)靠(kao)基部(bu)(bu)通(tong)過(guo)體(ti)(ti)(ti)(ti)(ti)(ti)(ti)壁及(ji)胃腔(qiang)的(de)(de)(de)(de)向外突出(chu)(chu)，再長出(chu)(chu)觸(chu)手(shou)與(yu)口(kou)(kou)(kou)即(ji)(ji)形(xing)(xing)(xing)(xing)(xing)成(cheng)(cheng)(cheng)(cheng)(cheng)芽(ya)體(ti)(ti)(ti)(ti)(ti)(ti)(ti)，以后芽(ya)體(ti)(ti)(ti)(ti)(ti)(ti)(ti)與(yu)母(mu)體(ti)(ti)(ti)(ti)(ti)(ti)(ti)分(fen)離即(ji)(ji)形(xing)(xing)(xing)(xing)(xing)成(cheng)(cheng)(cheng)(cheng)(cheng)新(xin)的(de)(de)(de)(de)個體(ti)(ti)(ti)(ti)(ti)(ti)(ti)。但在(zai)(zai)藪枝螅(xi)(xi)（Obelia）所形(xing)(xing)(xing)(xing)(xing)成(cheng)(cheng)(cheng)(cheng)(cheng)的(de)(de)(de)(de)芽(ya)體(ti)(ti)(ti)(ti)(ti)(ti)(ti)與(yu)母(mu)體(ti)(ti)(ti)(ti)(ti)(ti)(ti)不分(fen)離則形(xing)(xing)(xing)(xing)(xing)成(cheng)(cheng)(cheng)(cheng)(cheng)了群(qun)(qun)體(ti)(ti)(ti)(ti)(ti)(ti)(ti)。其(qi)次(ci)，也可以通(tong)過(guo)分(fen)裂(lie)(lie)方式進行無性(xing)生(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)(zhi)(zhi)(zhi)，主要發(fa)(fa)生(sheng)(sheng)(sheng)(sheng)(sheng)在(zai)(zai)水(shui)(shui)(shui)(shui)螅(xi)(xi)型(xing)(xing)，例(li)如(ru)海(hai)葵可以縱(zong)分(fen)裂(lie)(lie)，缽水(shui)(shui)(shui)(shui)母(mu)的(de)(de)(de)(de)幼(you)(you)(you)體(ti)(ti)(ti)(ti)(ti)(ti)(ti)以橫分(fen)裂(lie)(lie)進行無性(xing)生(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)(zhi)(zhi)(zhi)。此外水(shui)(shui)(shui)(shui)螅(xi)(xi)型(xing)(xing)一般具有(you)很強的(de)(de)(de)(de)再生(sheng)(sheng)(sheng)(sheng)(sheng)能力，例(li)如(ru)，將(jiang)水(shui)(shui)(shui)(shui)螅(xi)(xi)切成(cheng)(cheng)(cheng)(cheng)(cheng)數段，條件合宜時(shi)每段都(dou)可以再生(sheng)(sheng)(sheng)(sheng)(sheng)成(cheng)(cheng)(cheng)(cheng)(cheng)一個新(xin)的(de)(de)(de)(de)個體(ti)(ti)(ti)(ti)(ti)(ti)(ti)，再生(sheng)(sheng)(sheng)(sheng)(sheng)時(shi)口(kou)(kou)(kou)與(yu)反口(kou)(kou)(kou)端(duan)的(de)(de)(de)(de)極性(xing)不變，但口(kou)(kou)(kou)端(duan)的(de)(de)(de)(de)再生(sheng)(sheng)(sheng)(sheng)(sheng)速(su)度比(bi)反口(kou)(kou)(kou)端(duan)迅(xun)(xun)速(su)。所以水(shui)(shui)(shui)(shui)螅(xi)(xi)型(xing)(xing)的(de)(de)(de)(de)再生(sheng)(sheng)(sheng)(sheng)(sheng)現(xian)象(xiang)也被認(ren)為(wei)(wei)是(shi)(shi)(shi)無性(xing)生(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)(zhi)(zhi)(zhi)的(de)(de)(de)(de)一種(zhong)(zhong)方式。有(you)些生(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)(zhi)(zhi)(zhi)出(chu)(chu)現(xian)在(zai)(zai)多(duo)數水(shui)(shui)(shui)(shui)螅(xi)(xi)型(xing)(xing)及(ji)所有(you)的(de)(de)(de)(de)水(shui)(shui)(shui)(shui)母(mu)型(xing)(xing)，除少數種(zhong)(zhong)類例(li)如(ru)水(shui)(shui)(shui)(shui)螅(xi)(xi)為(wei)(wei)雌(ci)雄同(tong)體(ti)(ti)(ti)(ti)(ti)(ti)(ti)之外，絕(jue)大多(duo)數種(zhong)(zhong)類為(wei)(wei)雌(ci)雄異體(ti)(ti)(ti)(ti)(ti)(ti)(ti)（或(huo)(huo)(huo)異群(qun)(qun)體(ti)(ti)(ti)(ti)(ti)(ti)(ti)）。生(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)(zhi)(zhi)(zhi)細(xi)胞(bao)(bao)來(lai)源于(yu)間(jian)細(xi)胞(bao)(bao)，然(ran)后遷移到(dao)固(gu)定的(de)(de)(de)(de)位置(zhi)上(shang)(shang)形(xing)(xing)(xing)(xing)(xing)成(cheng)(cheng)(cheng)(cheng)(cheng)生(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)(zhi)(zhi)(zhi)腺(xian)。水(shui)(shui)(shui)(shui)螅(xi)(xi)蟲(chong)(chong)綱(gang)的(de)(de)(de)(de)動物(wu)生(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)(zhi)(zhi)(zhi)腺(xian)來(lai)源于(yu)表(biao)(biao)(biao)皮層(ceng)(ceng)(ceng)，例(li)如(ru)水(shui)(shui)(shui)(shui)螅(xi)(xi)，水(shui)(shui)(shui)(shui)螅(xi)(xi)水(shui)(shui)(shui)(shui)母(mu)的(de)(de)(de)(de)生(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)(zhi)(zhi)(zhi)腺(xian)位于(yu)放(fang)射管(guan)下(xia)或(huo)(huo)(huo)垂(chui)(chui)唇周圍，但都(dou)是(shi)(shi)(shi)來(lai)源于(yu)表(biao)(biao)(biao)皮層(ceng)(ceng)(ceng)細(xi)胞(bao)(bao)。缽水(shui)(shui)(shui)(shui)母(mu)綱(gang)的(de)(de)(de)(de)生(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)(zhi)(zhi)(zhi)細(xi)胞(bao)(bao)起源于(yu)胃層(ceng)(ceng)(ceng)位于(yu)胃囊低部(bu)(bu)。珊瑚(hu)綱(gang)的(de)(de)(de)(de)生(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)(zhi)(zhi)(zhi)細(xi)胞(bao)(bao)是(shi)(shi)(shi)由胃腔(qiang)中的(de)(de)(de)(de)隔膜上(shang)(shang)發(fa)(fa)生(sheng)(sheng)(sheng)(sheng)(sheng)，也是(shi)(shi)(shi)內(nei)(nei)胚(pei)層(ceng)(ceng)(ceng)來(lai)源。腔(qiang)腸動物(wu)只有(you)生(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)(zhi)(zhi)(zhi)腺(xian)，沒(mei)有(you)出(chu)(chu)現(xian)生(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)(zhi)(zhi)(zhi)導管(guan)及(ji)生(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)(zhi)(zhi)(zhi)附屬腺(xian)，生(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)(zhi)(zhi)(zhi)細(xi)胞(bao)(bao)成(cheng)(cheng)(cheng)(cheng)(cheng)熟之后由口(kou)(kou)(kou)排(pai)出(chu)(chu)，或(huo)(huo)(huo)由體(ti)(ti)(ti)(ti)(ti)(ti)(ti)壁破裂(lie)(lie)而釋放(fang)。受(shou)(shou)精(jing)作用依(yi)不同(tong)的(de)(de)(de)(de)種(zhong)(zhong)而異，或(huo)(huo)(huo)在(zai)(zai)體(ti)(ti)(ti)(ti)(ti)(ti)(ti)外海(hai)水(shui)(shui)(shui)(shui)中進行，或(huo)(huo)(huo)在(zai)(zai)垂(chui)(chui)管(guan)的(de)(de)(de)(de)表(biao)(biao)(biao)面，或(huo)(huo)(huo)在(zai)(zai)胃腔(qiang)內(nei)(nei)生(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)(zhi)(zhi)(zhi)腺(xian)的(de)(de)(de)(de)部(bu)(bu)位進行。卵(luan)裂(lie)(lie)是(shi)(shi)(shi)完(wan)全的(de)(de)(de)(de)，形(xing)(xing)(xing)(xing)(xing)成(cheng)(cheng)(cheng)(cheng)(cheng)中空的(de)(de)(de)(de)囊胚(pei)，經(jing)移入(ru)法(fa)或(huo)(huo)(huo)內(nei)(nei)陷法(fa)形(xing)(xing)(xing)(xing)(xing)成(cheng)(cheng)(cheng)(cheng)(cheng)原(yuan)腸胚(pei)，結(jie)果形(xing)(xing)(xing)(xing)(xing)成(cheng)(cheng)(cheng)(cheng)(cheng)兩層(ceng)(ceng)(ceng)細(xi)胞(bao)(bao)，即(ji)(ji)兩個胚(pei)層(ceng)(ceng)(ceng)，內(nei)(nei)部(bu)(bu)成(cheng)(cheng)(cheng)(cheng)(cheng)團的(de)(de)(de)(de)細(xi)胞(bao)(bao)為(wei)(wei)內(nei)(nei)胚(pei)層(ceng)(ceng)(ceng)，將(jiang)來(lai)形(xing)(xing)(xing)(xing)(xing)成(cheng)(cheng)(cheng)(cheng)(cheng)成(cheng)(cheng)(cheng)(cheng)(cheng)體(ti)(ti)(ti)(ti)(ti)(ti)(ti)的(de)(de)(de)(de)胃層(ceng)(ceng)(ceng)，外表(biao)(biao)(biao)的(de)(de)(de)(de)一層(ceng)(ceng)(ceng)為(wei)(wei)外胚(pei)層(ceng)(ceng)(ceng)，將(jiang)來(lai)形(xing)(xing)(xing)(xing)(xing)成(cheng)(cheng)(cheng)(cheng)(cheng)成(cheng)(cheng)(cheng)(cheng)(cheng)體(ti)(ti)(ti)(ti)(ti)(ti)(ti)的(de)(de)(de)(de)表(biao)(biao)(biao)皮層(ceng)(ceng)(ceng)。實心(xin)的(de)(de)(de)(de)原(yuan)腸胚(pei)迅(xun)(xun)速(su)延(yan)長，體(ti)(ti)(ti)(ti)(ti)(ti)(ti)表(biao)(biao)(biao)出(chu)(chu)現(xian)纖(xian)毛，形(xing)(xing)(xing)(xing)(xing)成(cheng)(cheng)(cheng)(cheng)(cheng)了自(zi)由游(you)泳的(de)(de)(de)(de)浮(fu)浪(lang)幼(you)(you)(you)蟲(chong)(chong)（planula）。浮(fu)浪(lang)幼(you)(you)(you)蟲(chong)(chong)早期沒(mei)有(you)口(kou)(kou)(kou)及(ji)胃腔(qiang)，游(you)泳一段時(shi)間(jian)之后，固(gu)著在(zai)(zai)水(shui)(shui)(shui)(shui)草、巖石(shi)或(huo)(huo)(huo)其(qi)他物(wu)體(ti)(ti)(ti)(ti)(ti)(ti)(ti)上(shang)(shang)發(fa)(fa)育(yu)成(cheng)(cheng)(cheng)(cheng)(cheng)水(shui)(shui)(shui)(shui)螅(xi)(xi)型(xing)(xing)體(ti)(ti)(ti)(ti)(ti)(ti)(ti)，或(huo)(huo)(huo)再經(jing)過(guo)出(chu)(chu)芽(ya)生(sheng)(sheng)(sheng)(sheng)(sheng)殖(zhi)(zhi)(zhi)(zhi)形(xing)(xing)(xing)(xing)(xing)成(cheng)(cheng)(cheng)(cheng)(cheng)群(qun)(qun)體(ti)(ti)(ti)(ti)(ti)(ti)(ti)。淡水(shui)(shui)(shui)(shui)生(sheng)(sheng)(sheng)(sheng)(sheng)活的(de)(de)(de)(de)水(shui)(shui)(shui)(shui)螅(xi)(xi)沒(mei)有(you)幼(you)(you)(you)蟲(chong)(chong)期，其(qi)受(shou)(shou)精(jing)卵(luan)直(zhi)接發(fa)(fa)育(yu)。
巧笑倩兮
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