A stalked jellyfish Stenoscyphus inabai (Kishinouye, 1893) (Stauromedusae), found at The Jawbone, Port Phillip Bay, Victoria.
I have recently taken an interest in Stauromedusae, having collected two single specimens over the last 10 years. I have corresponded with Claudia Mills at the University of Washington (Mills 2012) and examined the small collection of Stauromedusae available in Museum Victoria. I was therefore delighted when, on 11 April 2012 on a Field Naturalists Club of Victoria (FNCV) Marine Research Group excursion, I collected 11 specimens of S. inabai that were living on Zostera muelleri, Irmisch ex Ascherson 1867 at The Jawbone, Williamstown. The 11 specimens were of a range of sizes, including juveniles from 3.5 mm to 8 mm, two specimens (15 mm and 17 mm) being mature with visible gonads, and a third specimen of a mature size (15 mm) which did not exhibit developed gonads. Ten of these specimens (Fig. 1) were retained for photography; as the eleventh was damaged, I released it where it was found.
Robert Burn collected a twelfth specimen some 10 metres away, also on Z. muelleri (Fig. 1). This was a 20 mm specimen with a much greener colour and a much greater number of anchors and secondary tentacle groups (16 instead of 8) and rows of gonads (8 pairs instead of 4) (Fig. 2 A, B). The presence of this specimen gave rise to discussion that could be resolved only by examination of further material.
Accordingly, on 7 July 2012 a second visit was made to the Jawbone by Robert Burn, Melanie Mackenzie, Leon Altoff and the author, with the intention of finding more of these animals. It was a cold clear sunny day with an excellent low tide, and the Stauromedusae could be seen easily in the shallow still water, attached to Zostera muelleri (Figs. 3 and back cover). In total, about 25 specimens were found, almost all adults with gonads. The colour of specimens varied considerably more than in those seen in April and it was agreed that the bright green specimen from April fell within the colour range of the species.
Fifteen specimens (Fig. 4) were selected to be examined more closely. A range of colours was selected, as were the only two juveniles (8 and 9 mm, with no visible gonads) seen and all adult specimens (14-24 mm), which appeared to be 'fatter' than normal. Of the 15 specimens, 12 had 8 anchors and tentacle groups, the 9 mm juvenile (Fig. 2 G, H) had 9 anchors (which were very small and difficult to count), and appeared to be recovering from damage with a missing peduncle and a slit down one side of the umbrella. A 22 mm specimen had 10 anchors and tentacle groups (Fig. 2 E, F) and a 20 mm specimen had 12 anchors and tentacle groups (Fig. 2 C, D, Fig. 6).
A final visit to the Jawbone on 4 August 2012, in poor weather, yielded a 12 mm juvenile specimen, which was used for live nematocyst observations.
In total, 38 specimens have been seen and three of them (7.9%) have clearly visible additional anchors and tentacle groups, matched with additional rows of gonads, giving perfect pentamerous, hexamerous and octamerous symmetry.
Zagal (2008) observed that of the 3790 specimens of the stauromedusa Haliclystus antarcticus Pfeffer, 1889 [as Haliclystus auricula (Rathke, 1806) (Miranda et al. 2009)] she examined, 16 specimens (0.4%) exhibited pentamerous or hexamerous symmetry. She has suggested that the cause may be either environmental or due to a lack of genetic diversity in the population.
Interestingly, immediately next to the somewhat sparse beds of Zostera muelleri, in slightly deeper water, there were luxuriant beds of Heterozostera nigricaulis (Kuo 2005) which seemed to be completely devoid of Stauromedusae.
One final observation from this day was of one specimen of the sessile ctenophore, Coeloplana willeyi Abbott, 1902, observed in the field on the same seagrass as the Stauromedusae. A second, partially digested, specimen was found inside the umbrella of one of the Stauromedusae. Also found in the collecting jar were two small crustacean carapaces. This suggests that C. willeyi, in addition to small crustaceans, is a potential food source for Stauromedusae.
These animals have all been identified as S. inabai (Kishinouye, 1893) and not Depastromorpha africana Carlgren, 1935, since all specimens lack the remnant primary tentacle and glandular cushions on the outer tentacles.
Examination of discharged live nematocysts and comparison with the table of undischarged nematocysts published in Zagal et al. (2011) is not inconsistent with this identification.
All specimens collected in April have been photographed in detail and preserved in 96% ethanol to allow for future DNA studies. They have been lodged with Museum Victoria in accordance with the FNCV Marine Research Group's collecting permit, registration numbers NMVF190059-NMVF190063.
The deformed specimens collected in July have been photographed and preserved in 96% ethanol and lodged with the Museum Victoria, registration number NMVF192289.
Dan McInnes' question as to where they go when their habitat is not present still lacks a definite answer. The full life stages of Stauromedusae remain little known and the story of the 'hydropolyp without tentacles', Microhydrula limopsicola (Jarms and Tiemann 1996) is instructive (Miranda et al. 2010). Specimens of this species, collected on living bivalve shells from the South Shetland Islands on 24 December 1991 and maintained as a live colony ever since (after asexually reproducing and migrating to glass surfaces) were shown to be only a phase of the life cycle of a stauromedusa when DNA analysis was performed and the species synonymised with Halicystus antarcticus Pfeffer, 1889 (Miranda et al. 2010).
Finally, Kishinouye (1902: 5) notes: 'As the body has adhesive apparatus at both its extremities, it can effect a locomotion very much like that of a leech' (Fig. 3, back cover and 5).
I am pleased to present here some live colour images of this species' development, behaviour, habitat and deformities.
Subsequent to the completion of this paper, a further specimen was observed and photographed by Trevor McMurrich in November 2012 at Curlewis, Outer Corio Bay, Port Phillip Bay. The specimen was found on the seagrass, Heterozostera nigricaulis (Kuo 2005) in 50 cm of water and was relocated to a rock to be photographed. It exhibited a vibrant green shade very similar to the octameric specimen collected in April 2012 at the Jawbone. This specimen exhibited normal symmetry.
I would like to thank Robert Burn and Melanie Mackenzie for their assistance with collecting specimens, Claudia Mills for the many emails about these animals, Jeanette Watson for teaching me how to examine the nematocysts, John Kuo for kindly sending me his paper on Heterozostera, Hugh Kirkman for confirming the species of seagrass present at the Jawbone and, finally, Leon Altoff for kneeling for long periods in very cold water in the middle of winter to capture images. I also thank Trevor McMurrich for his interesting observation at Curlewis.
Jarms G and Tiemann H (1996) On a new hydropolyp without tentacles, Microhydrula limopsicola n.sp., epibiotic on bivalve shells from the Antarctic. Scientia Marina 60, 109-115.
Kishinouye K (1902) Some new Scyphomedusae of Japan. Journal of the College of Science Tokyo 17, 1-17.
Kuo J (2005) A revision of the genus Heterozostera (Zosteraceae). Aquatic Botany 81, 97-140.
McInnes DE (1989) A Stalked Jellyfish (Stauromedusae) found at Black Rock, Port Phillip Bay. A first Recording in Australia. The Victorian Naturalist 106, 86-92.
Mills CE (2012) Stauromedusae: list of all valid species names. Electronic internet document available at http:// faculty.washington.edu/cemills/Staurolist.html. Published by the author, web page established October 1999, last updated 29 March 2012.
Miranda LS, Collins AG and Marques AC (2010) Molecules Clarify a Cnidarian Life Cycle--The "Hydrozoan" Micro hydrula limopsicola Is an Early Life Stage of the Staurozoan Haliclystus antarcticus. PLoS ONE 5: e10182. doi:10.1371/ journal.pone.0010182.
Miranda LS, Morandini AC and Marques AC (2009) Taxonomic review of Haliclystus antarcticus Pfeffer, 1889 (Stauromedusae, Staurozoa, Cnidaria), with remarks on the genus Haliclystus Clark, 1863. Polar Biology 32, 1507-1519.
Zagal CJ (2008) Morphological abnormalities in the stauromedusa Haliclystus auricula (Cnidaria) and their possible causes. Journal of the Marine Biological Association of the United Kingdom 88, 259-262.
Zagal CJ, Hirano YM, Mills CE, Edgar GJ and Barrett NS (2011) New records of Staurozoa from Australian coastal waters, with a description of a new species of Lucernariopsis Uchida, 1929 (Cnidaria, Staurozoa, Stauromedusae) and a key to Australian Stauromedusae. Marine Biology Research 7, 651-666.
Received 14 March 2013; accepted 4 July 2013
PO Box 3177, Murrumbeena, Victoria 3163
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|Publication:||The Victorian Naturalist|
|Date:||Oct 1, 2013|
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