STAUROMEDUSAE UK

An online guide to the Stalked jellyfish (Stauromedusae) found
around the coastal waters of the United Kingdom and Ireland.
Includes notes on their identification, and where and how to find them.

Site profile for Long Rock reef, Long Rock, Cornwall.
Long Rock Reef, OS Grid. Ref. SW 4985 3082, is a long, but narrow, intrusion of granite, the reef running north-east to south-west from the lower part of the shore. On the lowest tides the reef extends to a rock called Ryeman. The granite is particularly obvious on the eastern side of the reef, the harder rock, and large blocks, affording protection from south-easterly winds.

On the western edge of the reef there is a considerable amount of degraded Mylor slate running down a large part of the reef. The degraded Mylor slate here helps support a diverse range of fauna and flora and runs parallel to an Eelgrass bed that is exposed on low spring tides.

Anyone reading this that unaware of the importance of Eelgrass beds, as a habitat, should be made aware of their importance and understand that the habitat is protected. So care should be taken if planning a visit, or when dog walking in the area on low tides, and so as not to damage the habitat. This is especially important at the moment as the Eelgrass bed is in quite a vulnerable state after the 2013/14 winter storms, and the habitat has been significantly reduced in size.

The following short article was sent for inclusion in the Seaquest South West Newsletter.

David Fenwick has been assessing the damage caused by the recent storms in Mounts Bay, and largely to see how the storms might have affected the local stalked jellyfish populations. A night time visit was made on 01.03.14 to assess the state of the Long Rock Eelgrass bed, the inspection so worrying, that a visit was made in daylight the following day to confirm what had been seen. The Eelgrass bed was seriously damaged, and possibly up to 50% had been lost. On examining images, local geologist Peter Ealey stated the damage is a good example of contemporary wave quarrying, an apt name for such a devastating loss of habitat. At the north end of the Eelgrass bed, which was previously exposed above the water line, there is now a large intertidal lagoon separating the beach from the Eelgrass bed itself (see night image); the bed has also suffered gouging, especially in its center. Soft Mylor slate bedrock that was once under the Eelgrass, has in places been smashed into blocks, and in places the original ground level has decreased by over two feet. The site is well known for its stauromedusae populations and three BAP species have been recorded there. On 7th May 2012 hundreds of Haliclystus octoradiatus were recorded on Eelgrass, Zostera marina, at the site. The site is also known for its populations of rock boring piddocks, with a 200m long colony of Common and Little piddock being seriously affected. Given the extent of the damage, the Eelgrass bed may take some time to recover, especially because it is now even more vulnerable to the affects of the south-westerly winds it faces.

Before and after storm damage at Long Rock

Images of the devastation at Long Rock can be found on the APHOTOMARINE website.

Records with images

02.04.14. Long Rock, near Penzance, Cornwall. 48 specimens. 7 Calvadosia cruxmelitensis and 41 Haliclystus octoradiatus. Small lowershore reef with pools drainining into one another, area NW of the main Long Rock reef, approx. SW49753092 (Memory Map Grid Ref.). Stalked jellyfish mostly on Chondrus crispus, Gracilaria gracilis and other species of red algae. Six Haliclystus octoradiatus specimens found feeding, five on amphipods and one on a small Sea spider. Overcast weather, extra low spring tide, higher than predicted because of wind direction and low pressure. Considerable storm damage and sediment removal seen on shore as a result of 2013/14 storms, especially the Valentine Storm. Gracilaria gracilis seen recolonising new areas of shallow rocky pools that have been created further up the shore as a result of storms and sediment removal. Haliclystus octoradiatus seen taking advantage of this and moving further up the shore where the algae occurs. No stauromedusae were observed on the west side of Long Rock reef on Chondrus crispus, which is now sparse as a result of wave quarrying, or on the Eelgrass bed, probably as a result of extensive damage to the habitat. David Fenwick.

Calvadosia cruxmelitensis 1
Specimen on Chondrus crispus in pool at SW 49743 30967.
Calvadosia cruxmelitensis 2
Specimen on Polyides rotundus in pool at SW 49741 30966.
Calvadosia cruxmelitensis 3
Specimen on Gracilaria gracilis in pool at SW 49735 30968.
Calvadosia cruxmelitensis 4
Specimen on Polyides rotundus in pool at SW 49718 30952.
Calvadosia cruxmelitensis 5
Specimen on Chondrus crispus in pool at SW 49718 30952.
Calvadosia cruxmelitensis 6
Specimen on Chondrus crispus in pool at SW 49802 30910.
Calvadosia cruxmelitensis 7
Specimen on Chondrus crispus in pool at SW 49789 30908.
Haliclystus octoradiatus 1
Specimen on Chondrus crispus in pool at SW 49744 30964.
Haliclystus octoradiatus 2
Specimen on Chondrus crispus in pool at SW 49741 30966.
Haliclystus octoradiatus 3
Specimen on Chondrus crispus in pool at SW 49741 30966.
Haliclystus octoradiatus 4
Specimen on Chondrus crispus in pool at SW 49738 30966.
Haliclystus octoradiatus 5
Specimen on Polyides rotundus in pool at SW 49738 30966.
Haliclystus octoradiatus 6
Specimen on Gracilaria gracilis in pool at SW 49732 30968.
Haliclystus octoradiatus 7
Specimen in pool at SW 49728 30953.
Haliclystus octoradiatus 8
Specimen on Polyides rotundus in pool at SW 49726 30954.
Haliclystus octoradiatus 9
Specimen feeding on amphipod at SW 49726 30954.
Haliclystus octoradiatus 10
Specimen on Polyides rotundus in pool at SW 49727 30954.
Haliclystus octoradiatus 11
Specimen feeding on amphipod at SW 49723 30950.
Haliclystus octoradiatus 12
Specimen feeding on amphipod at SW 49710 30947.
Haliclystus octoradiatus 13
Specimen on Chondrus crispus in pool at SW 49709 30944.
Haliclystus octoradiatus 14
Specimen feeding, Chondrus crispus at SW 49727 30938.
Haliclystus octoradiatus 15
Specimen on Chondrus crispus in pool at SW 49735 30955.
Haliclystus octoradiatus 16
Specimen on Chondrus crispus in pool at SW 49735 30955.
Haliclystus octoradiatus 17
Specimen on Chondrus crispus in pool at SW 49735 30955.
Haliclystus octoradiatus 18
Specimen on Chondrus crispus in pool at SW 49735 30955.
Haliclystus octoradiatus 19
Specimen on Chondrus crispus in pool at SW 49735 30955.
Haliclystus octoradiatus 20
Specimen on Chondrus crispus in pool at SW 49802 30910.
Haliclystus octoradiatus 21
Specimen feeding on amphipod in pool at SW 49802 30910.
Haliclystus octoradiatus 22
Specimen on Chondrus crispus in pool at SW 49802 30910.
Haliclystus octoradiatus 23
Specimen on Chondrus crispus in pool at SW 49802 30910.
Haliclystus octoradiatus 24
Specimen on Chondrus crispus in pool at SW 49802 30910.
Haliclystus octoradiatus 25
Specimen on Chondrus crispus in pool at SW 49802 30910.
Haliclystus octoradiatus 26
Specimen on Chondrus crispus in pool at SW 49802 30910.
Haliclystus octoradiatus 27
Specimen on Chondrus crispus in pool at SW 49802 30910.
Haliclystus octoradiatus 28
Specimen feeding on amphipod in pool at SW 49802 30910.
Haliclystus octoradiatus 29
Specimen on Chondrus crispus in pool at SW 49802 30910.
Haliclystus octoradiatus 30
Specimen in pool at SW 49802 30910.
Haliclystus octoradiatus 31
Specimen on Chondrus crispus in pool at SW 49800 30906.
Haliclystus octoradiatus 32
Specimen on Chondrus crispus in pool at SW 49800 30906.
Haliclystus octoradiatus 33
Specimen on Chondrus crispus in pool at SW 49788 30909.
Haliclystus octoradiatus 34
Specimen on Chondrus crispus in pool at SW 49790 30906.
Haliclystus octoradiatus 35
Specimen on Chondrus crispus in pool at SW 49784 30908.
Haliclystus octoradiatus 36
Specimen on Chondrus crispus in pool at SW 49784 30908.
Haliclystus octoradiatus 37
Specimen on Chondrus crispus in pool at SW 49784 30908.
Haliclystus octoradiatus 38
Specimen on Polyides rotundus in pool at SW 49735 31006.
Haliclystus octoradiatus 39
On Gracilaria gracilis in new pools at SW 49735 31006.
Haliclystus octoradiatus 40
On Gracilaria gracilis in new pools at SW 49736 31014.
Haliclystus octoradiatus 41
On Lomentaria articulata at 50 07 33.09N 05 30 9.942W

Images of habitat for above record.

Lowershore rocks NW of Long Rock reef -1
Lowershore rocks NW of Long Rock reef -2
Lowershore rocks NW of Long Rock reef -3
Lowershore rocks NW of Long Rock reef -4
Lowershore rocks NW of Long Rock reef -5
Lowershore rocks NW of Long Rock reef -6
Lowershore rocks NW of Long Rock reef -7

Moderate risk of damage to habitat, Eelgrass (Zostera marina) and BAP species of stauromedusae, by dogs and dog walkers. Long Rock is very popular with dog walkers. This needs to be addressed, either through education (publicity or signage) or prohibition (a year round ban), and whether or not the area is included within proposed MCZ or not.

This part of the website is "UNDER CONSTRUCTION", details and text may be unchecked. Adding profiles and records for each site can be quite time consuming, especially during periods of recording.

Stauromedusae Site profile Long Rock reef Cornwall uk