Type Chordates: tsarin da kuma ci gaban da Amphioxus

Development of Amphioxus kuma ta din-din wuri na dogon lokaci kasance wani asiri. Yanzu masana kimiyya sani ga wasu da cewa wannan shi ne wakilin irin Chordates tsaye ba ci gaba.

Janar halaye na da irin Chordates

Kifi, halittar dabba mai kafafuwa, da abubuwa masu rarrafe, da tsuntsaye, dabbobi masu shayarwa - duk wadannan dabbobi ne wakilin da irin Chordates. Abin da unites irin daban-daban kwayoyin? Sai dai itace cewa su duk da na kowa shirin tsarin.

A core na jiki ne da axial kwarangwal, wanda ake kira a tsirkiya. A Amphioxus shi ci gaba cikin rayuwa. Sama da tsirkiya ne na tsarin jijiya tube. A lokacin metamorphosis mafiya yawa daga cikin wakilan da irin shi ne kafa laka da kuma kwakwalwa. Karkashin axial kwarangwal hanjin dimbin yawa kamar yadda wani bututu. A makogwaro na tsirkiya ne gill slits. A jinsin cewa rayuwa a cikin ruwa, wannan alama an riƙe, yayin da ƙasar ne halayyar kawai na da amfrayo ci gaba.

Tarihi na samu Amphioxus

Me Amphioxus ci gaba na dogon lokaci sa mai yawa na shawara da kuma tambayoyi? Gaskiyar ita ce, na dogon lokaci an dauke shi a mollusk. Amphioxus (photo kasa misalta ta waje tsarin) gaske kama wadannan dabbobi. Ya yana da taushi translucent jiki da kuma kawaici a cikin ruwa yanayi - a cikin m ruwa tekuna da kuma tekuna. Amma musamman da ciki kungiyar ta yiwu ga gano su a raba din raka'a.

Bugu da kari, godiya ga} Petra Pallasa da Aleksandra Kovalevskogo aka samu cewa wadannan dabbobi ne magabatan zamani vertabrate. Masana kimiyya kira wadannan kwayoyin da suke zaune burbushin. An yi imani da cewa lancelet ba samo asali, kamar yadda daidai saba da yanayi da kuma hanyar rayuwa a cikin rashi na fafatawa a gasa.

Features na waje tsarin

Saboda jiki siffar wannan dabba yana da wani sabon abu da sunan - lancelet. Photo nuna cewa jiki kama wani tsoho m kayan aiki da cewa an wasa a garesu. An kira a Lancet. Wannan kama daidai misalta da fasali na waje tsarin.

Amphioxus jiki ya kai a kalla tsawon 8 cm. Yana wajaba tarnaƙi, kuma ya nuna a karshen. A gefe daya daga cikin tsaye Musulunci jiki suranta fins - dorsal da caudal. Lancelet raya karshen na jiki da aka binne shi a yashi. A gaban shi ne preoral bakin dutse, kewaye da tentacles.

Kwarangwal kuma tsokoki

Development of Amphioxus halin da dagewa da tsirkiya cikin ransa. A wani tufka da shi lullube tare da dukan jiki daga gaba da baya karshen. A garesu na tsirkiya aka shirya a kan wani yawan tsokoki. Wannan tsarin da locomotor tsarin damar Amphioxus matsawa gaba ɗaya. Muscle contractions kai ga lankwasawa na jiki, kuma ta hanyar da tsirkiya ne ta gyãrawa.

ciki tsarin

Amphioxus gawarwakin samar da duk physiological tsarin. Narkewa kamar gabatar baka bude, makogwaro da kuma hanjinsu ta hanyar-tube da hanta outgrowth, wanda ya yi aikin aiki na prostate gland shine yake. By irin ikon Amphioxus ne heterotrophic tace feeders. Wannan tsari ne da hankali hade tare da numfashi, wanda yana da za'ayi ta hanyar da gills da kuma dukan jiki surface.

A okolozhabernuyu kogo da kuma gabobin bude selection. Suna wakilta yawa guda biyu shambura - Nephridia. Amphioxus jijiyoyi unclosed. Ya kunshi ventral da dorsal tasoshin.

Amphioxus haihuwa gabobin kira gonads. Wannan guda biyu gland na wani yawa wanda za a iya isa har zuwa 25. Amphioxus ne iri guda ba dabbobi. Saboda haka, da suka ci gaba ovaries ko testes. Al'aura ducts, waɗannan dabbobi ba su da. Saboda haka, Kwayoyin shigar da rami a hutu okolozhabernuyu gonads ko jiki katangu.

Sake bugun, kuma ci gaba da

Haihuwa gabobin da Amphioxus samar da su waje hadi. Gametes suna located a cikin ruwa, inda suka coalesce. Mace sa su qwai bayan faduwar rana a cikin dukan yanayi, fãce hunturu. Su jam sel dauke da sosai kadan kwai gwaiduwa da halin kananan size - game da 100 microns.

Ko kafin crushing na kwai abinda ke ciki Amphioxus bambanta cikin uku jam yadudduka: ecto, meso da indodem. A lokacin m ƙungiyoyin kowanne daga abin da Forms Game da sashin jiki tsarin.

Development of Amphioxus ya ba da wani ra'ayi game da siffofin da wannan tsari a chordates. Ya kunshi jerin m tafiyar matakai na hadi, tsakiyan nonon, gastro da kuma neurulation organogeneza.Razmnozhenie Amphioxus, kazalika da su kara ci gaba da ake da nasaba da ruwa. Na kwan da ya hadu a cikin 4-5 days tasowa tsutsa. Yana yana da wani size up to 5mm da gudãna, da yardar kaina a cikin ruwa anta da yawa cilia. A larval mataki yana game watanni 3. A dare shi yakan ga ruwa surface, da kuma rana sinks.

Amfioksidy - don haka ya kira giant larvae na Amphioxus, wanda shi ne sabon abu na duniya dabba. Na farko, su aka kuskure ga manya. Amma da yawa nazarin shi aka ƙaddara cewa su zauna ba fãce a kan surface na ruwa a cikin abun da ke ciki na plankton. Amfioksidy cewa zai iya isa 11 mm, riƙe da dukan siffofin da larval Tsarin. Jikinsu yana rufe da cilia, kusan undeveloped baka tentacles okolozhabernaya rami da gonads.

Saboda haka Amphioxus ne m marine chordates. Sun kasance a cikin subtype bescherepnyh, aji Golovohordovye. Amphioxus halin da sedentary salon, kasancewa iri guda ba dabbobi da waje hadi da kuma kai tsaye ba irin ci gaban.