Photograph © by Penny Martin (Orkney)
12 July 2011, Birsay, Orkney Islands
is a bioluminescent
True jellyfish are in the class Scyphozoa.
Aequorea are widely found around the British Isles with records washed up on the shore from Cornwall and Suffolk as well as the Orkneys. However, the records are not complete at the moment because the genus is often not recognised and any reports are welcome. Aequorea species need experts to distinguish between them. Aequorea forskalea has been positively identified and recorded from around the British Isles. The two reports of Aequorea I have received have both been in July 2011.
There was a large stranding of jellyfsh-like Aequorea forskalea on Treyarnon Beach, North Cornwall coast.
Jellyfish & related Medusa
- The Dutch Aequorea specimens emit light because they have
caught/eaten micro-organisms ("zeevonk"=Dutch name) that lighten up when
- The observation that medusae with retracted tentacles brightly emit
light and those with elongated tentacles do emit light at all, supports the
hypothesis that the medusae retract their tentacles when they have a full
- The Dutch Aequorea specimens, moreover elongate all their tentacles
in order to catch their food. When they have caught enough food they retract
- No support was found for the hypothesis that the Dutch Aequorea
specimens have a limited number of specialised elongated tentacles.
- When a tentacle is retracted, it is curled, shortening this tentacle
From: Dhugal J. Lindsay [EMail:email@example.com]
Sent: Monday, July 24, 2000 3:36 AM
Subject: Re: tentacle elongation in hydromedusae 2
I know it's not a hydromedusa but just thought that while we were on
subject of elongated tentacles...
Most people probably know by now the observation that the coronate
scyphomedusan Atolla is pretty much always seen in vivo with one elongated
hypertrophied tentacle and only one. We recently observed it to catch
Nanomia bijuga using this tentacle. Any interested people should refer to
Hunt, J.C., and D.J. Lindsay, 1998. Observations on the behavior of
(Scyphozoa: Coronatae) and Nanomia (Hydrozoa: Physonectae): use of the
hypertrophied tentacle in prey capture. Plank. Biol. & Ecol., 45(2):
or drop me a line for a reprint.
Subsequent SEM has identified the presence of nematocysts on the distal
of this tentacle although we'll have to catch another before we can better
characterize the morphology and distriution.
Can't say I've ever seen Aequorea in the mesopelagic with some but not
tentacles elongated. I do have at least one new species of Aequorea from the
Indian Ocean south of Mauritius if anyone is interested in giving the genus
Ciao for now,
Dr. Dhugal J. Lindsay
Marine Ecosystems Research Department
Japan Marine Science and Technology Center (JAMSTEC)