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.

A basic key to UK stauromedusae with images
Please note that because of the number of images on this page the images may be initially slow to load.

A basic key to assist with the identification
of stauromedusae found in the UK

The following is a basic key that can be used in the field to identify species of stauromedusae. The key divides UK stauromedusae into three sections, the species in each section may be unrelated, but all will possess a character or characters that can be used to best determine the species in the field using techniques that will be described further down this page. It must be noted that although Stalked jellyfish may appear quite similar there are often quite marked differences between intertidal species, so there is often no need to remove of collect specimens for the purpose of identification. See notes on "Stauromedusae as FOCI species" at the end of the key.

Section One includes species that possess primary tentacles (anchors) - Haliclystus.

Section Two includes species with no primary tentacles (anchors), but possess white nematocysts (stinging cells)
- Lucernariopsis and Lucernaria.

Section Three consists of species that are generally found without primary tentacles (anchors) and much reduced amounts of oral spotting (nematocysts). Craterolophus convolvulus juveniles and adults may be found to possess small peg-like primary tentacles or residual stumps of ones, as seen in the image Craterolophus convolvulus with residual primary tentacles. There may also be some white spotting on the gonads and tips of the arms in Craterolophus convolvulus, the spotting is never as pronounced as as defined as other species, which is why the species has been placed in this section.
- Craterolophus and Depastrum.

Section One
Species with obvious primary tentacles (anchors).

1. Nematocysts usually many, but as few as 1 in juveniles, present on arms or between arms of bell, anchors sub-globular or globular knobs.
............. Haliclystus octoradiatus
2. No nematocysts present, anchors longer than wide, coffee bean-shaped.
............. Haliclystus auricula

Section Two
Species with no anchors, possessing nematocysts (white spotting).

3. Nematocysts irregularly arranged on bell face. Aboral papillation giving bell a granular appearance.
............. Calvadosia campanulata
4. Nematocysts +/- symetrically arranged forming a Maltese cross on bell face, arms short, usually maroon.
............. Calvadosia cruxmelitensis
5. Nematocysts generally aligned around edge of cruciform-shaped bell, arms short, arranged in four pairs.
............. Lucernaria quadricornis

Section Three
Species generally without primary tentacles (anchors) and much reduced amounts of oral spotting (nematocysts).

6. Bell with no arms, stalk as long as bell .............8
7. Bell with arms, short stalked.........................9
8. Arms absent, gonads horseshoe shaped, stalk as long as bell, bell <10mm diameter, thistle-like in ventral view.
............. Depastrum cyathiforme
9. Bell elongated, goblet shape, short stalked, arms short, tentacles short.
............. Craterolophus convolvulus

The key here has been written by the author of this site, and may need a little tweaking to get it just right. Any comments on the key will be greatly appreciated as it is something I'd like to get right as it is perhaps one of the most important features of this website. E-mail Dave Fenwick

Please refer to ''Species Accounts'' for more information.
Please note that because this website is largely still under construction, some species accounts may be incomplete.

Various texts were checked in compiling the above key, but reference must be made to "Handbook of the Marine Fauna of North-West Europe". Edited by P.J. Hayward and J.S. Ryland.

Photography has a very important role in determing species in the field, and especially where people do not have the facilities or time to keep stauromedusae alive, or have time for their later release and transfer to a suitable algae. Collection and transfer can be done quite successfully for a number of species, but not all, and given the digital technology that is now available, and with some patience, all but the smallest juvenile stauromedusae can be identified using a reasonably priced digital compact camera with good macro facility.

See "Photographing stauromedusae" for tips on using cameras to identify species.

Stauromedusae as FOCI species

Potentially four species of stauromedusae are being used at the current time as FOCI species in relation to the proposed Marine Conservation Zones in the UK. Collection for the purpose of identification or photography is frowned upon, especially in relation to photography, as images / evidence, needs to be provided of species in-situ. So where possible a suitable amount of time needs to be paid to getting the photography just right and and so that species can be identified using images.

The four FOCI species include Calvadosia cruxmelitensis, Calvadosia campanulata and Haliclystus auricula. Of course this makes three, but the latter, Haliclystus auricula, contains Haliclystus octoradiatus, which was resurrected in 1997; but its resurrection has only been recently applied. Haliclystus octoradiatus is an extremely variable species and there may be problems in separating it in the field from Haliclystus auricula. Haliclystus octoradiatus is likely to be a much more common species than H. auricula and should probably be considered first in terms of identification in the UK.

There is only one other confirmed report, of another Haliclystus species in the UK, Haliclystus salpinx, and from near John O' Groats in Scotland. It is therefore unlikely that this species will be confused with either of the other Haliclystus here. Therefore if Haliclystus auricula and Haliclystus octoradiatus are considered together as a single FOCI species; and where an identification cannot be made to species level, but only to genus, because of the presence of anchors (primary tentacles); then records should be accepted for Haliclystus sp., and to lessen the need for collection to determine identification, afterall these species are in need of conservation which is why they are FOCI species in the first place, and collection cannot be justified for such a potentially sensative species.

The exact rules on this are currently being clarified by Natural England and DEFRA, but it is very likely that Haliclystus sp. will be accepted for the reporting of Haliclystus as a FOCI species, and so lessen any impact from the "need to identify", which is potentially an issue. The FOCI species status somewhat places a burden on species involved, for the risk is that sensative species will be singled out for the sake of recording.

Articles on Morphological Variation

On the occurence of twin-headed specimens of stauromedusae by David Fenwick
(On Stauromedusae UK)

On the Variation of Haliclystus octoradiatus
by Edward T. Browne, B.A., University College, London.
Quarterly Journal of Microscopical Science 1895. s2-38:1-8.

(External weblink)

Anatomical images of species found around the UK

Calvadosia cruxmelitensis
(Click on image link to view larger 1200 x 800 images)

Calvadosia cruxmelitensis oral surface of bell close-up
Calvadosia cruxmelitensis gonadal sacs close-up
Calvadosia cruxmelitensis manubrium (mouth) closed
Calvadosia cruxmelitensis manubrium (mouth) open -1
Calvadosia cruxmelitensis manubrium (mouth) open -2
Calvadosia cruxmelitensis secondary tentacles -1
Calvadosia cruxmelitensis secondary tentacles -2
L. cruxmelitensis arm with nematocysts in parallel rows

Haliclystus octoradiatus
(Click on image link to view larger 1200 x 800 images)

Haliclystus octoradiatus lateral view of bell
Haliclystus octoradiatus oral surface
Haliclystus octoradiatus side view of oral surface
Haliclystus octoradiatus manubrium (mouth) 1
Haliclystus octoradiatus manubrium (mouth) 2
Haliclystus octoradiatus manubrium (mouth) 3
Haliclystus octoradiatus manubrium (mouth) 4
Haliclystus octoradiatus anchors (primary tentacles) 1
Haliclystus octoradiatus anchors (primary tentacles) 2
Haliclystus octoradiatus anchor (primary tentacle) 1
Haliclystus octoradiatus anchor (primary tentacle) 2
Haliclystus octoradiatus white nematocysts 1
Haliclystus octoradiatus white nematocysts 2
Haliclystus octoradiatus white nematocysts 3
Haliclystus octoradiatus white nematocysts 4
Haliclystus octoradiatus basal disk
Haliclystus octoradiatus gonad
Haliclystus octoradiatus gonadal sacs
Haliclystus octoradiatus lateral surface of bell
Haliclystus octoradiatus stalk and basal disk
Haliclystus octoradiatus secondary tentacles 1
Haliclystus octoradiatus secondary tentacles 2

Variation in anchor (primary tentacle) morphology
in Haliclystus octoradiatus

Haliclystus octoradiatus anchor (primary tentacle) 1

The next three images are of anchors from a single individual. Image 2 shows an anchor with no tentacle protruding, commonly seen in the species; image 3 shows the tentacle head protruding through the anchor, not uncommon in the species; and image 4 shows the heads of two tentacles protruding through the anchor, which is less common.

Haliclystus octoradiatus anchor (primary tentacle) 2
Haliclystus octoradiatus anchor (primary tentacle) 3
Haliclystus octoradiatus anchor (primary tentacle) 4

Haliclystus octoradiatus anchor (primary tentacle) 5
Haliclystus octoradiatus anchor (primary tentacle) 6
Haliclystus octoradiatus anchor (primary tentacle) 7

Anchor morphology in Haliclystus octoradiatus is therefore variable from specimen to specimen but also highly variable within certain individuals. Keys and descriptions describing a distinctive anchor shape for Haliclystus octoradiatus may not be relied upon.

Above images taken using either a Canon 5D MkII or 550D DSLR camera, MP-E 65mm lens, MT-24EX Twin Flash, a full set of Kenko extension tubes and 1.4x Kenko TelePlus Pro 300 teleconverter. Camera setup.

Images of additional species will be added on obtaining or finding suitable specimens to photograph during 2014.

Comparative Images

Image comparing bell shapes of Craterolophus convolvulus, Calvadosia campanulata, Calvadosia cruxmelitensis and Haliclystus octoradiatus

Larger images for printing

Guide to compare the four most common species of stauromedusae / Stalked jellyfish found around the coasts of Devon and Cornwall. Calvadosia campanulata, Calvadosia cruxmelitensis, Haliclystus octoradiatus and Craterolophus convolvulus. (jpg file, 200Kb)

A basic key to assist with the field identification of stauromedusae found around the coast of the UK
(jpg file, 274Kb)

Anatomical images Key UK species Stauromedusae