Mild-stinging jellyfishes reported off coastal waters of Sri Lanka

Abstract

Cnidarian jellyfishes (medusae) are reported to have both positive and negative impacts on ecological and socioeconomic aspects throughout the world. However, knowledge on the jellyfish in Sri Lankan waters is poor due to lack of literature. A systematic jellyfish survey was carried out in the coastal waters of Sri Lanka from January 2017 to April 2018, and samples were collected using commercial beach seins, scoop nets and zooplankton nets and preserved in 5% formalin/seawater. Meantime, few samples collected by some other local researchers were also received to the Museum of Department of Aquaculture and Fisheries, Wayamba University of Sri Lanka. Non-hazardous species morphologically identified using standard guides and keys are reported here. During the study, Aequorea pensilis (n=104), Cassiopea andromeda (n=23), Crambione mastigophora (n=4), Eirene ceylonensis (n=30), Eirene hexanemalis (n=80), Liriope tetraphylla (n=11), Lychnorhiza malayensis (n=25), and Olindias singularis (n=4) were reported. Moreover, Cephea cephea (n=1) was reported for the first time in Sri Lankan waters from Great Basses. It was identified with the aid of taxonomic features including the bell of 300 mm in diameter, a large dome at apex, the dome covered with about 30 large, pointed warts, in each octant 8 large velar lappets between two very small ocular lappets, hundreds of long, tapering filaments, and 3 inter-rhopalar canals per each octant. Furthermore, an Aurelia sp., two Malagazzia spp. and another two Eirene spp. were identified only up to the genus level. Findings warrant further studies on socio-economic aspects of mild-stinging jellyfishes off the coastal waters of Sri Lanka.