The IOI-MOC team at the University of Malta said it recently observed underwater the jellyfish strobilation process.
The team explained that Jellyfish demonstrate a highly convoluted underwater life cycle, in which small planula larvae released by the adult jellyfish medusae develop into polyps (similar to the ones in coral) which attach to and settle on hard substrata, before undergoing divisions into multiple small jellyfish known as ephyrae, which eventually develop into adult jellyfish themselves. Hard substrata, such as concrete jetties or wharves, or even the surface of organisms, like jellyfish, are settled upon by the polyps. Hence, each planula larvae can give rise to several medusae and the upsurge in concrete wharves and jetties are partly responsible for the current upsurge in jellyfish numbers.
Currently, jellyfish sightings being submitted by the public refer to just two species – the mauve stinger (Pelagia noctiluca, accounting for over 95% of all sightings reports) and salps, which are not considered as jellyfish by biologists but are innocuous pelgaic tunicates.
Currently, the island of Lampedusa, lying just over 100km to the west of the Maltese archipelago, is bearing the full brunt of a mauve stinger jellyfish, of much higher proportions than in Maltese waters.
The IOI-MOC team is expecting the flamboyant and innocuous fried egg jellyfish (Cotylorhiza tuberculata), a favourite with people on the Gozo ferry and with divers, to make its first appearance this year in about a month's time, close to the opening of the lampuki season.
The Spot the Jellyfish initiative is coordinated by Dr. Alan Deidun, Prof. Aldo Drago and staff of IOI-MOC, and enjoys the support of the Malta Tourism Authority (MTA) and of Nature Trust, Friends of the Earth, EkoSkola, the BlueFlag Malta programme and Sharklab.
The reporting is done by simply matching the sighted jellyfish with a simple visual identification guide, giving the date and time of the sighting, and indicating the number of jellies seen. Sightings can be also reported online or submitted through an SMS on 79 222 278, or by sending an email message to ioi-moc@um.edu.mt.
Strange jellyfish not included on the leaflet should be caught and kept in a bucketful of seawater prior to contacting IOI-MOC staff for retrieval to attempt a definite identification of the species. If this is not possible, photos of the same individuals should be taken.