- Gnathostomulid
Taxobox
name = Jaw worms
regnum =Animal ia
subregnum =Eumetazoa
branch =Bilateria
superphylum =Platyzoa
phylum = Gnathostomulida
phylum_authority = Ax, 1956
subdivision_ranks = Orders
subdivision =
*Filospermoidea
*Bursovaginoidea Gnathostomulids, or jaw worms, are a small phylum of nearly microscopic marine
animal s. Most measure between 0.5 and 1 mm long. Like flatworms they have a ciliated epidermis, but are unique in having but one cilium per cell. [Ruppert, Edward E., Fox, Richard S., Barnes, Robert D. (2004) "Invertebrate Zoology" (7th ed.). Brooks/Cole-Thomson Learning, Belmont, USA] They have nobody cavity , and no circulatory or respiratory system. Each gnathostomulid is simultaneously hermaphrodite, possessing an ovary and a testis. They are characterized by a specialized, muscular jaw, which they use to scrape smaller organisms off of the grains of sand that make up their anoxic seabed mud habitat.Barnes, R.F.K. et al (2001). "The Invertebrates: A Synthesis". Oxford: Blackwell Science.] This bilaterally symmetrical pharynx with its complex cuticular mouth parts make them appear closely related torotifer s and their allies, together making up theGnathifera .There are approximately 100 described species and certainly many more as yet undescribed. The known species are grouped in two orders. The filospermoids are very long and are characterized by an elongate rostrum. The bursovaginoids have paired sensory organs and are characterized by the presence of a penis and a sperm-storage organ called a bursa.
Gnathostomulids have no fossil record.
References
*ITIS|ID=57405|taxon=Gnatostomulida
* [http://tmcr.usuhs.mil/tmcr/chapter46/gnathostom.htm Tropical Medicine Central Resource - Gnathostomiasis]
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