North Pacific Ocean m.v. Main Express Captain K Owen. Kaohsiung to Oakland. Observers. the Master, J Dixon. 1st Officer, R Walker, 2nd Officer. R. Walker. 3rd Officer.
12- 15 May 1985. Whilst on passage, sightings of numerous ‘Men-of-War’, were an every day occurrence’'. At first sighting, what appeared to be a patch of decoloured water, approximately 15 m, by 30 m, was seen. this was a yellow greenish colour, and looked to be smooth, as though a film of oil was on the surface. As the vessel closed on this patch it could be seen that it was a shoal of ‘Men-of-War’ (which we subsequently decided were Velella ) so dense that no water could be seen between them. Similar sightings took place all day, and in the afternoon, long wind blown steaks of yellowy green, could be seen stretching for thousands of metres. consisting of million upon millions of organisms.
On closer inspection from the main deck, the colour of the patches was the same, but when the vessel passed through a patch and scattered individual bubbles the usual deep could be seen around the clear bubble. The average size was about 4-5 cm but varied greatly as there were such vast amounts.
The following day, these observations took on a different appearance. Vast numbers were still seen, but were not observed as discoloured patches as it was now overcast, whereas the previous day had been sunny. It was assumed that the diffusion of light through the millions of bubbles was responsible for the yellowy green appearance.
We travelled through the Velella for five days, by which time they had thinned out considerably from the solid patches observed on the 12th and 13th, but they were still visible in large numbers.
We had covered over 2,000 nautical miles since the first sightings on the 10th and were constantly intrigued as to how far this solid mass stretched.
A specimen , small in size unfortunately (originally packed in a container of spirit which was smashed and replaced with one containing gin) was obtained.
Whilst the colour of the Velella was originally an azure blue, it changed to a brown/ yellow colour shortly after immersion in the gin. It was oval in shape, and measured about 2cm by 1cm. Beneath the raft were short tentacles surrounding a central mouth. There was a clear sail, roughly triangular in shape, set at an angle across the raft. The sail was about 2cm high and 2cm wide across the oval. Also visible when viewed from above was a series of concentric rings.
Position of ship 38 deg 00’ N 179deg 54’W
Dr F Evans of the Dove Marine Laboratory, University of Newcastle on Tyne comments:
The specimen included with this report was the skeletal remains of Velella velella, or ‘By-the-wind-sailor’ confirming the shipboard identification in the best possible way, by the forwarding of the actual animal.
I have never seen a report of such truly astronomical numbers, and find it quite awe -inspiring.
The intense blue is characteristic of many animals that live right at the surface in warmer seas, presumably a camouflage. Polewards such animals may appear greener. In the case of Velella, this blue colour appears to be soluble in alcohol, hence the decolourisation when immersed in gin!
Velella is an animal whose anatomy and so on is very well known, but whose life history is not. We even lack even knowledge of how long it lives, whether it is a few months or many years.
May I point out once more that without the Voluntary Observing Fleet, this immense outburst could well have gone unnoticed.