Basking sharks are welcome visitors to the British coastline during the summer months, when they swim close to the surface straining the sea water through modified gills to collect plankton. The species is listed as endangered and the MCS promotes and collects public sightings, through the Basking Shark Watch (BSW) project to try to help us understand more about this enigmatic animal.

Until recently, while summer sightings were quite common, nothing was known about the animals distribution during the winter months. Recently (May 14 2009), however, researchers have filled in the blanks. Satellite based tracking systems have followed basking sharks as they overwinter at depths between 200m and 1km, while migrating through the tropical waters of the Atlantic. The sharks were observed to stay at these depths for weeks or months at a time, effectively vanishing from sight!

For more information:

Science News Report

To report a sighting, or for more information on basking sharks in UK waters:

MCS basking sharks reportings

Scientists around the globe are working hard to try and find out, MarineSpecies.org now have over 122 000 species, and estimate a total of 230 000. During their work, however, they have found that a lot of our ‘species’ are really only synonyms for the same organism. The leader in the synonym race is the breadcrumb sponge (Halichondria panicea). This is common on a range of substrates, and adopts a wide range of shapes and colours in different habitats – if you dive you’ve almost certainly seen it! Its predilection to changing its colour and shape have resulted in scientists giving it no less than 56 synonyms…

MarineSpecies.org is affiliated to the Census of Marine Life, which readers might also find interesting.

The full moon of late November shone down on our second sea mouse (Aphrodite aculeata) survey in Loch Fyne. There had been an unusual sighting several years ago, of 8 or 12 sea mice in close proximity and in shallow water, whilst on a weekend dive trip with Preston Sub Aqua Club. Since then we have arranged two expeditions with PSAC and our local MCS group to survey the area and look for any repetitions of this sighting.

Aphrodite is a segmented marine worm, not rare, but in our experience only seen occasionaly as solitary creatures.  To see a cluster like this is certainly unusual, and with limited information available on their life cycle, may be related to spawning activities. The creature is an unusual looking worm, about the size of a mouse, and with ‘mousy’ brown hairs (setae) on it’s back. One of the most unusual features is an array of iridescent hairs around the base of the body. These hairs are being studied with a view to developing high-tec photonic systems.

The surveys so far have only been a partial success, in that we have found sea mice, but not in significant numbers. On the Saturday we suffered severe windchill in the 2 Preston boats that were used, with rain squalls thundering up the Loch. Sunday was much more pleasant starting with flat calm water and patches of sun breaking through the cloud, though later the windchill meant that hats were still needed. One hat left in the loch-side accomodation meant that a diver who usually has more sense, had to protect his head with a borrowed white towel. It created the strange appearance of Mother Theresa cruising up the loch with her diving flock sat around her feet.

On this occasion we found three sea mice,  two of which were in close proximity, but no larger clusters. The question is wether this is significant, or would 14 divers have seen this number on any similar substrate at any time of year? One appealing option for the future is to survey the same area, at a different (warmer) time of year. Certainly the attractive accomodation and the two groups cameraderie make this a likely option for next year.

Gordon.