Alison Cawood Staurozoans Taxonomy and Relationships to Other Scyphozoans Staurozoans are sessile stalked jellyfish In other words they look like a cross between an anemone and a medusa This has lead to confusion about their position within the phylum Cnidaria and as to whom they are most closely related Descriptions and placement of this group have changed several times since it was first recognized The group of stauromedusae was first designated by Ernst Haeckel 1881 in the Challenger Reports It was one of four orders in the class that Haeckel referred to as Acraspedae The other orders were Peromedusae Cubomedusae and Discomedusae Acraspedae were defined as possessing no velum lobes on the umbrella gastric filaments and often had life histories that involved an alternation of generations between benthic polyps and pelagic medusae Order Stauromedusae was defined as an acraspedid medusa with eight principle tentacles possibly with secondary tentacle bunches on the ends of the primary tentacles and possessing a stomach and genitalia divided into four segments Haeckel did not include the stalked adults as part of the order description Two families were identified Tesseridae and Lucernaridae The Tesseridae were first described by Haeckel They were said to be free swimming medusae with an apical elongation The family Lucernaridae had first been described in 1847 by Johnston but had not been part of a separate order In Haeckel s redescription of the family he does not mention that they are benthic The only mention of the benthic lifestyle is one phrase when describing the peduncle what was referred to as an apical elongation in Tesseridae of the newly described species Lucernaria bathyphila In 1910 Mayer summarized what was known about the world s medusae He discussed the class Scyphozoa the class that Haeckel referred to as the Acraspedae The term Scyphozoa was first used by Lankester in 1881 The description of the scyphozoans was very similar to the description given by Haeckel for the acraspedans According to Mayer the class Scyphozoa contained five classes Stauromedusae Carybdeidae referred to as Cubomedusae by Haeckel Cornatae referred to as Peromedusae by Haeckel Semaeostomeae and Rhizostomae together comprised the Haeckel s Discomedusae Mayer described the Stauromedusae as primarily sessile possessing eight tentacles with clusters at the ends and having non ciliated planula larvae Mayer said that stauromedusae were the most degenerate of all scyphomedusae He described the same two families that were mentioned by Haeckel but said that Tesseridae were known only from Haeckel The first volume of Libbie Hyman s treatise of the invertebrates was published in 1940 Hyman listed class Scyphozoa as containing five orders similar to those described by Mayer Cubomedusae Stauromedusae Cornatea Semaeostomeae and Rhizostomae She describes all staurozoans as being sessile and attached by a stalk She does not discuss Tesseridae or any exception to the sessile lifestyle In 1961 Kramp reviewed the medusae of the world He described the same five families of Scyphozoa as Hyman His description of order 1 Alison Cawood Stauromedusae was similar to that of Hyman He discussed two families of staurozoans Eleutherocarpidae and Cleistocarpidae Lucerenariinae Lucernaridae is listed as a subfamily of Eleutherocarpidae A few years later Thiel 1966 reviewed the evolution of scyphozoans He listed the same five orders as Hyman and Kramp However he grouped the Cubomedusae and the Stauromedusae into subclass Scyphostomidae saying that they comprised the base of the Scyphozoa In 1973 a jellyfish symposium was held in Japan During this conference results were presented suggesting that cubomedusae were significantly different from other scyphozoans and should therefore be placed in their own group class Cubozoa Werner 1973 The cubozoans were placed at the base of the medusa like organisms Uchida 1973 examined the systematic position of the stauromedusae He disagreed with Thiel and other authors who believed that staurozoans were near the base of the scyphozoans and were most closely related to cubomedusae Uchida argued that based on their distribution and morphology Stauromedusae was a more advanced order than Cornatae and were most closely related to Semaeostomeae He also discussed several versions of the families of stauromedusae and determined that there were four valid families Lipkeidae Kishinouyeidae Haliclystidae Lucernaridae from Haeckel and Cleisocarpidae During the late 1990 s the staurozoans were back to being considered the most basal scyphozoans Bridges et al 1995 discussed four orders of scyphozoans Stauromedusae Cornatae Semaeostomeae and Rhizostomae and placed the staurozoans at the base of the scyphozoans In 1997 Arai also placed the stauromedusae at the base of the scyphozoans She mentioned two families Cleistocarpidae and Eleutherocarpidae the same families described by Kramp in 1961 In 1998 Lutz et al discussed stauromedusae in the deep sea They found Lucernaria a genus discussed by Haeckel at hydrothermal vents This study was a return to some of the work done by Haeckel which had been largely ignored for over 100 years In 1999 Claudia Mills started a website with a list of all of the currently recognized species of staurozoans This list was compiled because there were no reliable references containing this information Mills listed 50 species in five families Depastridae Kyopodiidae Lipkeidae Kishinouyeidae and Lucernariidae She considered the two families listed by Arai Cleistocarpidae and Eleutherocarpidae to be suborders This was the classification system that she used in her gelatinous zooplankton guide published in 2003 Wrobel and Mills In 2004 Marques and Collins took the first serious look at scyphozoan phylogenetics They determined that the stauromedusae along with the extinct Conulatae were molecularly and morphologically distinct enough to warrant their own class Staurozoa They argued that the medusa like organisms were more similar to one another than any of them were to the Anthozoa corals and anemones Based on this they created the subphylum Medusozoa containing the classes Staurozoa Cubozoa Scyphozoa with three orders and Hydrozoa The staurozoa were the base of the medusozoan lineages 2 Alison Cawood Collins and Daly described a new species of Lucernaria from the deep sea in 2005 Molecular studies were done to determine where the new stauromedusae should be placed within class