- published: 19 Nov 2015
- views: 195
Gnathostomulids, or jaw worms, are a small phylum of nearly microscopic marine animals. They inhabit sand and mud beneath shallow coastal waters and can survive in relatively anoxic environments. They were first recognised and described in 1956.
Most gnathostomulids measure 0.5 to 1 millimetre (0.020 to 0.039 in) in length. They are often slender to thread-like worms, with a generally transparent body. In many Bursovaginoidea, one of the major group of gnathostomulids, the neck region is slightly narrower than the rest of the body, giving them a distinct head.
Like flatworms they have a ciliated epidermis, but in contrary to flatworm, they have one cilium per cell. The cilia allow the worms to glide along in the water between sand grains, although they also use muscles, allowing the body to twist or contract, for movement.
They have no body cavity, and no circulatory or respiratory system. The nervous system is simple, and restricted to the outer layers of the body wall. The only sense organs are modified cilia, which are especially common in the head region.
The animal is anesthetized in Magnesium chloride, but animals are very slow moving anyway. Video taken by Ludwik Gąsiorowski.
บรรยายกระบวนวิชาสัตว์ไม่มีกระดูกสันหลัง ZOO3401 โดย รศ. สุภาวดี จุลละศร มหาวิทยาลัยรามคำแหง
Video of an anesthetized Gnathostomulida. You can easily see the muscular pharyngeal bulb and the tip of the jaws in brown. You can also see the head and the thin tail.
Trata-se da saga de um Gnathostomulídeo que sai de sua terra natal (Baía de Kiel) e tenta realizar seu sonho no Brasil - mais precisamente na Universidade Federal Fluminense, na aula de acelomados e pseudocelomados da professora Cinthya!)
Video of a Gnathostomulida not anesthetized. These animals are usually quite slow but stressed they can have some fast movements. You can easily see the muscular pharyngeal bulb and guess where are the jaws. You can also see the head and the thin tail.
Video aula para o curso de Ciências Biológicas da Pontifícia Universidade Católica de Campinas. Com as alunas: Ana Carolina Fernanda Sana Gabriela Novaes Sirlei Marques Vídeo Usado: https://www.youtube.com/watch?v=B5f9LWhMNCU
Here is a bunch of Limnognathia from Greenland swimming under the binocular microscope. Sorry for the shaking and the bad focus, I did that with my own camera. This video is more to show how they swim. It is interesting to point out that the swimming behaviour is very similar to the one of Gnathostomulida.
SPrytna gazella ucieka swoim oprawcom i nie daje za wygraną Extra tagi: lew, antylopa, żyrafa, afryka, safari, hieny, dzięciołHipopotam Aksolot Niedźwiedź Nosorożecszympans antylopa Kolcogłowy, cierniogłowy (Acanthocephala) Kolcogłowy (Acanthocephala). Wirki bezjelitowe (Acoelomorpha). Pierścienice (Annelida). Stawonogi (Arthropoda). Ramienionogi (Brachiopoda). Mszywioły (Bryozoa). Szczecioszczękie (Chaetognatha). Strunowce (Chordata). Parzydełkowce (Cnidaria). Żebropławy (Ctenophora). Lejkogębce (Cycliophora). Szkarłupnie (Echinodermata). Szczetnice (Echiura). Kielichowate (Entoprocta). Brzuchorzęski (Gastrotricha). Szczękogębe (Gnathostomulida). Półstrunowce (Hemichordata). Ryjkogłowy (Kinorhyncha). Kolczugowce (Loricifera). Drobnoszczękie (Micrognathozoa). Mięczaki (Mollusca). N...