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.
By P. H. GOSSE, Esq., F.R.S., A.L.S.
The summer was over, but I still lingered at Weymouth. Spring tides came and went with tantalizing regularity; but, though the sea receded far below the lowest level reached in summer, it was almost unavailable to me. Day after day I used to go down and look upon the ledges, but fierce autumnal gales blew with characteristic violence and pertinacity, and huge seas rolled in, sweeping over the flats, shooting up in forcible jets from the fissures, and laying bare for a moment large tracts of inviting seaweeds, only to cover them the next a fathom deep.
In a brief interval of gentleness, however, I found an animal which had long been an object of desire to me, a normal form of the genus Lucernaria. The small, aberrant, vase-like species, L. cyathiformis, I had taken already; but I wished to see the more elegant sorts, which resemble in figure the trumpet-shaped flower of a Convolvulus, representations of which by the pencil of Mrs. Johnston I had been in the habit of admiring, in her husband's admirable ''History of British Zoophytes."
It was on the 3rd of October that I detached, at that sort of little natural pier that I have described under the Nothe cliffs, a frond of Fucus serratus, with a bushy tuft of Rhodomela subfusca growing parasitically on it. To one of the branchlets of the latter plant a little mass of jelly was adhering, which, on my dropping the branch into a phial of water, presently expanded, and I had the pleasure of seeing the bell-like form of Lucernaria auricula. It was a very young specimen, not much more than one-eighth of an inch in height; but I had got a clue to the search, and I subsequently obtained, through the month of October, many more. In spite of the gales and seas, I managed to drag up a good deal of the Fucus which is hereabout profusely fringed with Rhodomela, and also with Ceramium rubrum; and on these, as also occasionally on the Fucus itself, and once or twice on Padina, I found the Lucernariae.
My mode of examination was as follows. Collecting a basketful of the tufts at random, I brought them home; then one by one I waved them to and fro, in the tank of water, between my eye and the light, whereby the animals became distinctly discernible, and were easily detached. Sometimes four or five were scattered over one tuft of the parasitic plant, and it was rare to find a Rhodomela of any size, without one at least.
The specimens were evidently the young of the season; many were no larger than I have named; but some were as much as one-third of an inch in diameter. They were very beautiful, closely resembling a bell, or trumpet-mouthed monopetalous flower, with a short flexible footstalk, and a small, expanded, sucking-disk at the base. The substance was clear, transparent, gelatinous; the flower-like expansion thin and filmy, with the margin projecting into eight equi-distant points. From each of these points radiated about twenty slender tentacular threads, bearing at their extremities orange or yellow globules. The ovaries radiated in eight irregular bands from the centre of the flower to the marginal points, and from the centre itself projected a little, protrusile, four-cleft mouth; closely like the peduncle of a Thaumantias. Indeed I was strongly struck with the resemblance which the creature bore to a small Medusa, and I consider it as a link that connects the normal Actiniae with the Acalephae.
In some specimens there were eight little oval warts, which hung from the outside of the margin, placed midway between the angles or points. Montagu has made these warts the distinctive character of this species; but I think they are not to be depended on; for many of my specimens, not at all to be distinguished from these in form, colour, or habit, were destitute of the least trace of the warts. It is possible that it may be a distinction of sex.
The specimens were very difficult to preserve alive. The beautiful groups of globe-headed threads soon contracted and agglutinated into shapeless masses, the hold of the foot loosened, and the animal dropped helpless to the bottom, and decayed. Indeed, I found that the hold was very readily let go, even in health; the little animal travels quickly, causing itself to adhere to any substance, either by the contact of the tentacles, of the marginal warts, or of the foot-disk.
From what O. Fabricius says of the food of this species, - "vescitur oniscis," - I presented to one a little Gammarus locusta ; the Lucernaria strove to take in the prey with its mobile mouth, and succeeded in partially embracing it, holding it for several hours, after which it dropped it. The shrimp was early rendered powerless.
In colour these delicate creatures vary much. The expanded membrane is usually colourless ; but the mouth, the ovaries, the edges of the disk, and the foot display colour. This may be grass-green, olive, drab, whitish, or various shades of rose-pink. The warts are commonly whitish, and the tentacle-globules pale orange yellow. In some specimens, opaque-white specks were scattered over the disk, which in others were absolutely wanting. The nature of these I cannot conjecture.
In February of the present year (1854) Mr. Thompson of Weymouth was so kind as to send me up several specimens of what I take to be a distinct species, L. campanulata. It is less elegant, more cup or bell-shaped, with scarcely any perceptible stalk. These specimens were about an inch in height, more dense in texture, of a dark dull green hue.
My friend has favoured me with the following notice of the habits of this species. "The Lucernariae I find as follows: at extreme low water, beds of sea-grass (Zostera marina) are exposed; on some of these, little pools, four or five feet across and eighteen inches deep, are formed, the matted roots of the Zostera having been washed away. The bottom of the pools is of clear sand, with innumerable broken tubes of a species of Sabella (Terebella) and a few Pagurus bernhardus, all small specimens ; also Venus striatula and Mactra sultorum. On the surface of these little lakes, and round the edges, float the leaves of the Zostera which grow nearest the margin; and attached to these leaves on their under-sides, with the mouth and tentacles downwards, rests the Lucernaria on the watch for prey; at times in a state of rest, at others in constant motion. The heads of the tentacles possess great power of adhesion, and I expect you will find the filaments or threads highly developed."
The accompanying plate represents two specimens of Lucernaria auricula attached to a pendent thread of seaweed. In the foreground is that fine bivalve (Pectunculus glycimeris), which is taken in deep water in this Bay; its summit is covered with the common Acorn-shell (Balanus balanoides); on which rests the scarlet-lined Aesop-prawn (Pandalus annulicornis). Behind this spring two fronds of the Ladies' tresses (Laminaria phyllites). From the rock above the Lucernariae is growing a bushy tuft of a coarse but curious Alga (Ceramium echionotum); and below is seen a plant of exquisite structure, one of the most simple, but one of the most lovely of seaweeds, the Bryopsis plumosa.
