Nthawi ya Silurian ikamapita Padziko Lapansi (kuyambira 440 mpaka 420 miliyoni zapitazo), zolengedwa zambiri zamkati mwa madzi zidasinthika kwambiri. Zojambula zawo zasintha kwambiri: kuchokera ku mphete wamba, adasandulika ma arcs awiri, okhazikika ndi gawo lamafuta. Izi zidasintha pang'ono panjira yopanga oxygen. Kenako mkamwa wamkamwa unayamba kusintha. Chipilala chapamwamba chinalumikizana ndi chigaza, ndipo m'munsi chinangokhala chozungulira ndikuchita chibwano. Chifukwa chake zolengedwa zidakhala ndi kamwa yonse. Kusintha kotereku kwachitika pakati pa nsomba zakale zambiri, kuphatikizapo makolo akale a sterlet.
Izi zinasinthira mitundu kukhala nyama zodya nyama. Ngati kale pansi pamadzi zolengedwa zimakakamizidwa kudya plankton ndi algae yaying'ono, chifukwa sakanatha kutafuna chakudya chokulirapo, ndi nsagwada zopangidwa bwino anali wokhoza kupukutira ndi kupera zigawo zazikulu. Chifukwa cha izi, zakudya za zolengedwa zoterezi zakula kwambiri ndikufikanso ndi nsomba zazing'ono.
Tiyenera kumvetsetsa kuti makolo akale a sterlet, omwe adakhala zaka 400 miliyoni zapitazo, anali osiyana kwambiri ndi amakono. Tsoka ilo, asayansi sangathe kudziwa momwe amawonekera. Mwachidziwikire, nsomba za nthawi imeneyo zinali zokulirapo ndipo zimatha kusiyana pakapangidwe kake ndi maonekedwe ake. Anthu oyambirirawo, akunja kofanana ndi cholembera chamakono, adayamba kuwonekera zaka pafupifupi 120 miliyoni zapitazo.
Popita nthawi, mtunduwu watsimikizira kuti ndi umodzi mwamipanda ya nkhono kwambiri. Anapulumuka molimbika tsoka lililonse lapadziko lonse lapansi, adatha kusintha nyengo kusintha, komanso nthawi zonse amakhala limodzi ndi mitundu ina ya moyo.
Maonekedwe ndi mawonekedwe ake
Sterlet ndi nsomba yama cartilaginous. Alibe ma vertebrae m'thupi lake, ndipo ntchito zawo zimasinthidwa ndi mbale zolimba zomwe zimakhala kumbali. M'munsi mwa mafupa ndi mzere, womwe umawoneka ndi maliseche chifukwa cha matewo omwe amagawidwa kumbuyo kwake. Chigoba ndi mafupa a akulu ngakhale akuluakulu amakhala ndi cartilage.
Pakamwa pake timakankhira kutsogolo ndipo timafanana ndi kamlomo kabakha. Palibe mano pa nsagwada, koma chifukwa cha larynx wolimba ndi milomo yayikulu yamkamwa, ngakhale zidutswa zazikulu ndizoperera. M'munsi mwa thupi ndi chikhodzodzo cha kusambira chomwe chimalumikizana ndi chimbudzi. Pansi pamutu, pazophimba zapadera, mumakhala ma gill. Muli zotsegula zazing'ono zomwe zimalola mpweya kudutsa.
Sisiteryo imakhala ndi thupi lalitali, lothinikizidwa kumbali. Mutu umatambasulidwa ndipo umakhala ndi milomo yolumikizana. Pamunsi pamutu pali tinyanga tating'onoting'ono, tomwe ndi amtundu wina wa sturgeons.
Nsombazo zimagawika m'magulu awiri molingana ndi mutu: Ndi muzzle lakuthwa ndi kufufuma. Oyamba obadwa mwachilengedwe. Anthu omwe ali ndi mpweya wotumphukira amatha kuwonekeranso m'matupi amadzi, koma sangathe kubereka. Chosangalatsa ndichakuti, anthu ambiri omwe amawonekera nthawi yomwe akuwerekewa, amakhala ndi mfuti.
Thupi la nsomba limachita imvi ndipo limakhala ndi m'mimba, thupi limakutidwa ndi mamba ofanana ndi enamel. Pamutu pali mbale zamafupa zomwe zimateteza. Chomaliza sichimakhala pakatikati kumbuyo, koma chimasunthidwa kumchira. Yotsirizirayi ili ndi gawo lalitali komanso lalifupi.
Kukula kwapakati pa sterlet kumachokera ku 0.5 metres, koma makamaka anthu akuluakulu amatha kukula mpaka mamita 1.4. Amuna ndi akazi amtundu womwewo, kukula kwake, ndi kunja kwake sizosiyana.
Habitat - sterlet imapezeka kuti?
Sterlet amakhala m'mitsinje ndi nyanja kapena nyanja. Amapezeka kwambiri ku Yenisei, Northern Dvina ndi Ob. Amapezekanso m'mitsinje yambiri yoyenda mumadziwe a Nyanja Zachikuda, Azov ndi Caspian. Kuphatikiza apo, sterlet idalowa m'madzi ena othokoza chifukwa cha munthu yemwe adayambitsa kuti awonjezere. Pakadali pano, anthu ambiri amakhala m'malo otsatirawa:
- nsomba yayikulu imakhala pakati pa Irtysh,
- Kuban amadziwika kuti ndi malo akumwera kwambiri kwa sterlet, anthu ochepa amtunduwu amakhala mmenemu, koma chiwerengero chake chikukula pang'onopang'ono,
- Zaka zaposachedwa, Mtsinje wa Kama wayeretsedwa kwambiri chifukwa chakuchotsa mitengo, ndichifukwa chake nsomba zam'derali zidayamba kuchulukana mwachangu.
- zinthu sizikuyenda bwino papulatifomu ku Sura: chifukwa cha zinthu zabwino kwambiri, kuchuluka kwawo kukuchepa.
- mu Don ndi Urals nsomba zamtunduwu ndizosawoneka, mwina, anthu ena amasambira apa, koma sakhala moyo wokhazikika,
- kuonjezera kuchuluka kwa anthu, anthu mwabwinobwino amabweretsa sterlet ku Amur, Oka, Neman ndi Pechora,
- nsomba ndizofala ku Yenisei, masukulu akuluakulu ambiri amakhala kumeneko,
- Ob mtunduwu wayamba kukulira, nthawi ndi nthawi kukopa diso la munthu,
- Sterlet idabweretsa makamaka ku Dvina, koma kwa nthawi yayitali sinathe kuzika mizu chifukwa cha nyengo yozizira.
Nsomba zimakonda kukhazikika m'malo osungira pansi kapena pansi pamchenga, zimafunanso madzi oyera kwambiri. Amuna amakhala nthawi yawo yambiri pamalo ozama. Akazi amakonda kumira pansi.
Kodi sterlet amadya chiyani?
Achichepere amadya plankton ndi nyama zazing'ono zam'madzi. Amayenda pansipa ndipo amatola ndi pakamwa pawo chilichonse chomwe angadye. Tizilomboti tili pa nsagwada yapamwamba ndipo timagwira ngati zounikira kuti tipeze chakudya chothandiza pa izi.
Mukamakula, zakudya zomwe nsomba zimasintha pang'ono komanso zimadalira jenda. Popeza anyani amadzisambira akuya, amagwira nsomba zochepa. Akazi, ogwiritsa ntchito nthawi yawo yambiri pansi, amadya tizilombo toyenda m'madzi, nyongolotsi, crustaceans yaying'ono, ndi mazira a nsomba zina.
Ngakhale kuti sterlet imawonedwa ngati chilombo, imasankha kusankha nyama yaying'ono. Amapita kukasaka usiku kapena mumdima.
Kodi sterlet imakhala nthawi yayitali bwanji?
Kutalika kwa moyo wa sterlet ndikutali kwambiri poyerekeza ndi ena okhala m'madzi. Pafupifupi, m'malo abwino, nsomba zimatha kukhala ndi moyo mpaka zaka 30. Asayansi akukhulupiriranso kuti anthu ena amatha kufikira zaka 80. Sterlet imakula ndikukula kwa nthawi yayitali. Thupi lake limapangidwa kumapeto kwa zaka 5-7.
Mawonekedwe a machitidwe ndi moyo wawo
Sterlet ndi chilombo chomwe chimakhala m'malo osungirako ndi madzi oyera. Nthawi zina anthu amatha kupita kunyanja, koma nthawi zonse amabwerera mwachangu. M'nyengo yotentha, nsomba zimasambira m'madzi osaya, koma nyengo yozizira ikamachoka pama gombe mpaka kuya kwambiri ndikuyang'ana maenje ndi mabwawa kuti nthawi yozizira ikhale. Alendo osakumanako sadzamupeza, ndipo nsomba zidzakhala zotetezeka.
M'nyengo yozizira, sterlet imayamba kugwira ntchito. Amakhala nthawi yonse yopuma yomwe adapeza, samapita kokasaka. Thupi lake limagwera ngati makanema oimilira, chifukwa chomwe sichiyenera kulandira chakudya nthawi zonse. Ndikayamba masika, madzi oundana pamwamba pa mtsinje atasungunuka, anthu amayamba kuyenda kwambiri ndikupita kumtunda kuti akayambike.
Gulu la anthu
Sterlet amakhala m'matumba akulu, ndipo chiwerengero cha anthu amatha kukhala mazana angapo. Nsombazo zimasonkhanitsa chakudya limodzi ndikuyesetsa kusamalira ana. Mwinanso chifukwa cha chikhalidwe chomwe chitukuka kale kuti mtunduwu sunangowoneka padziko lapansi, komanso ukuwonjezeka.
Nthawi yachisanu ikadzafika, nsomba zonse zimafunafuna malo omwe mungadikirire kuzizira. Popeza mwapeza chovala chabwino kapena chomenyera, sterletyo imatsikira pansi kwambiri. Nthawi zina anthu ambiri amatha kusonkhana nthawi imodzi kotero kuti sangathenso kuyenda zipsewa zake momasuka. Kenako nsombazo zimakanikizidwa motsutsana, zimagonja ndipo zimangosunthasuntha.