[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.

Species in order Conophoralia tend to have larger sperm than those in Sceloperalia.

Bursovaginoids mostly live in oceans near the coasts, in depths of under 500 meters (1650 feet), most commonly around 300.