© The Authors, 2016. Journal compilation © Australian Museum, Sydney, 2016 
Records of the Australian Museum (2016) Vol. 68, issue number 1, pp. 23-30. 
ISSN 0067-1975 (print), ISSN 2201-4349 (online) 
http://dx.doi.Org/10.3853/j.2201-4349.68.2016.1656 
First Records of the Invasive 
“Upside-down Jellyfish”, Cassiopea 
(Cnidaria: Scyphozoa: Rhizostomeae: Cassiopeidae), 
from Coastal Lakes of New South Wales, Australia 
Stephen J. Keable and Shane T. Ahyong* 
Marine Invertebrates, Australian Museum Research Institute, 
1 William Street, Sydney, NSW 2010, Australia 
stephen.keable@austmus.gov.au • shane.ahyong@austmus.gov.au 
Abstract. Scyphozoans of the genus Cassiopea (Cassiopeidae) are notable for their unusual benthic 
habit of lying upside-down with tentacles facing upwards, resulting in their common name, “upside- 
down jellyfish”. In Australia, five named species of Cassiopea have been recorded from the tropical 
north. Cassiopea are frequently noted worldwide as invasive species and here, we report the first records 
of the genus and family from temperate eastern Australia on the basis of specimens collected from two 
widely separated coastal lakes, Wallis Lake and Lake Illawarra; these specimens represent southern 
range extensions of the genus by approximately 600 km and 900 km, respectively. Cassiopea from Lake 
Illawarra and Wallis Lake appear to represent different species, which we assign to C. ndrosia and C. cf. 
maremetens , respectively, noting morphological discrepancies from published accounts. 
Keywords. Introduced species, coastal lake, Cassiopea , Wallis Lake, Lake Illawarra, New South Wales 
Keable, Stephen J., and Shane T. Ahyong. 2016. First records of the invasive “upside-down jellyfish”, Cassiopea 
(Cnidaria: Scyphozoa: Rhizostomeae: Cassiopeidae), from coastal lakes of New South Wales, Australia. Records of 
the Australian Museum 68(1): 23-30. 
The medusa stage of the scyphozoan, Cassiopea (Cassiope¬ 
idae), is a distinctive marine or estuarine jellyfish, notable 
for its unusual, inverted, largely sedentary and benthic 
behaviour, imparting the common name “upside-down 
jellyfish”. This lifestyle typically involves the jellyfish 
lying in sheltered, shallow water with the aboral surface of 
the exumbrella facing downward onto sediments and the 
oral arms above. This posture and niche provides sunlight 
to algal endosymbionts (zooxanthellae) within the tissues 
although the jellyfish are also suspension feeding carnivores 
(Verde & McCloskey, 1998; Schembri etal. , 2009; Marsh & 
Slack-Smith, 2010). The severity of stings to humans from 
Cassiopea has been variably reported from mild or absent 
to severe (Southcott, 1982; Marsh & Slack-Smith, 2010). 
Although Cassiopea is readily recognized, the species 
level taxonomy is confused and requires reappraisal (Holland 
et al., 2004). Worldwide, at least 11 species are currently 
recognized: Cassiopea andromeda (Forskal, 1775), C. 
depressa Haeckel, 1880, C. frondosa (Pallas, 1774), C. 
medusa Light, 1914, C. maremetens Gershwin, Zeidler & 
Davie, 2010, C. mertensi Brandt, 1838, C. ndrosia Agassiz 
& Mayer, 1899, C. ornata Haeckel, 1880, C. xamachana 
* author for correspondence 
