Bursovaginoidea is one of the two orders in the phylum Gnathostomulida.[1]
Bursovaginoids are rather small, ranging from a half of a millimeter to a full millimeter in length.[2] Many species in the order Bursovaginoidea have a narrow neck, making their head stand out more than other bursovagionoids and all filospermoids.[3]
Bursovaginoids, unlike filospermoids, have paired sensory organs and a penis.[4] Also, all species in Bursovaginoidea have a sperm-storage organ called a bursa. In suborder Scleroperalia, the bursa is cuticular, while in Conophoralia it is not. Species in order Conophoralia tend to have larger sperm than those in Sceloperalia.[2]
Sightings of bursovaginoids have been reported in various parts of the world, including England and the north-western and south-eastern parts of the United States. Bursovaginoids mostly live in oceans near the coasts, in depths of under 500 meters (1650 feet), most commonly around 300.[5]
The order Bursovaginoidea contains 73 - 75 species and 24 genera in the following 10 families:[6][7]
Bursovaginoidea is one of the two orders in the phylum Gnathostomulida.
