Download - The Rock-Pools of Bundoran

The Rock-Pools of BundoranAuthor(s): J. E. DuerdenSource: The Irish Naturalist, Vol. 4, No. 1 (Jan., 1895), pp. 1-7Published by: Irish Naturalists' Journal Ltd.Stable URL: http://www.jstor.org/stable/25584877 .

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Vol. IV. JANUARY, 1895. No. 1.

THE ROCK-POOI,S OP BUNDORAN. BY J. E. DU3RDEN, A.R.C.SC. (London).

I^A$T summer, in connection with the Royal Irish Academy Fauna and Flora Committee, I had the opportunity, in com

pany with Prof. Johnson and Mr. Mitchell, of spending a little over a week in and around Bundorau, a delightful watering place, much frequented by people from the North of Ireland.

My object was to collect representatives of all the Zoophytes, embracing under this popular term the Hydroids, Sea anemones, andPolyzoa, at the same time not neglecting other forms of life which I might chance to come across,

Bundoran lies at the south-east corner of Donegal Bay, about four miles from the historically interesting town of

Ballyshannon. Taking the former as our centre, we made

collecting excursions to different parts of the bay, and so ob tained a good idea of the resources of the locality.

West of Bundoran, cliffs of Carboniferous limestone face the

sea, dipping to the south at an angle varying from five to ten degrees; but at low water a considerable extent of shore is laid bare, diversified by numerous rock-pools, caves, and

narrow inlets of the sea, the happy hunting-grounds of the

naturalist.

In the rock-pools the first object which attracts one is the

Purple Sea-urchin Strongylocentrotus lividzcs, I^amk., occurring in great numbers in little hollowS> their dark colour con

trasting strongly with the light rosy-pink calcareous alga Lithothanmion fiolyniorfthimfl, which lines most of these pools. This interesting sea-urchin is one of the most striking faunal

features of various localities along the west coast of Ireland, 1 For the name of this alga, and also for the others mentioned, I am

indebted to Prof. Johnson and to Mr. Mitchell,



2 The Irish Naturalist.

from Donegal Bay to Queenstown Harbour. It occurs nowhere else in the British Isles, but turns up again in the Channel Islands. It is capable of boring holes, probably by means of its teeth, in the soft limestone to a depth of one-half or more of its own height; where, however, the rocks, as at

Dog's Bay in Connemara, consist of the harder granite, the urchin is incapable of boringinto them, and simply rests upon the bottom of the pools. Many of them are partially covered

by empty shells, such as those of Patella, Purpura, ondLittorina.

Considering the spiny nature of their skeleton it is very diffi cult to conceive that this feature can be in any way concerned

with protection to the individual. Again, they are almost

invariably associated in the pools with luxurious growths of the light pink encrusting Lithothamnion polymorphum, to

which they offer the strongest contrast, almost suggestive of a

warning combination.

In some of the shallow pools, some distance above low water mark, we found numbers of the sea-slug Aplysiapunctata, Cuv,, their dark olive-green colour also contrasting strongly

with the light Lithothamnion. A few minutes sufficed to obtain two or three dozen, many of them in the act of laying their strings of brown-pink spawn.

On this part of the shore, and still more so on the rocks and cliffs north of Bundoran, are to be found more or less firm

masses of sand and fragments of shells built into tubes by the worm Sabellaria alveolaia, I4nn., and almost resembling a

honey-comb in appearance. These masses, no doubt, exer cise a preservative geological influence on the rocks, the hollows and irregularities about forming also a protection for various forms of life.

In one of the caves with a smooth floor covered by water, and with stalactitic and stalagmitic masses further in, we came across quite a crowd of small hermit-crabs, Pagurus, and very interesting it was to watch their little battles over the bodies of some of their unfortunate companions who had been torn from their protective gastropod shell. Here also I

met with a few specimens of Anemonia sulcata (Anthea cerms), Penn., of the variety with iridescent green tentacles tipped with red. This species, not so abundant in Donegal Bay, I have

met with in great numbers in Roundstone Bay, giving to the

beds of Zvstera there quite a flowery appearance. Actinia



The Rock-pools of Bundoran. 3

equina, lyinn., of the varieties hepaiica, rubra, olivacea, and

viridis was present everywhere. Under one of the ledges of

rock I met with a large group, thirty or forty individuals, of

the pretty little Corynactis viridis, Allm. This anemone varies

much in colour, although those belonging to the same colony are generally alike. In the present case the column was of a

light brown colour, the margin a rich bright orange, and the

tentacles green at the base, with greenish-brown stems and

white knobs. At Roundstone I have met with colonies of the

more typical green form. Specimens of Heliaeiis hellis, E). and S. were present in the cavities of the rock-pools, and also

the large Tealia erassicomis, Mtill. in considerable variety of colour. A single example of Cylista undata, Mtill. was

also obtained.

The coast to the north of Bundoran is varied by steep

precipices and sandy shores. Around Claddaghlagan not

much was obtained, nor along the beach in front of the east

portion of the town. Rogy Bay, a narrow inlet, was the best

locality for material washed up from the sea. Here were

obtained stems of Laminaria with quite thick forests of

Seriularia operculata, L,inn., growing on them, presenting almost the appearance of a fox's tail. The roots of the

Laminaria also yielded several species of encrusting Potyzoa. I may here record one fact in which I have always found the

west coast of Ireland to differ from the east coast, namely, in

the amount of material from considerable depths washed

ashore by storms. On such occasions we find suitable places on the east coast literally strewn with zoophytes and other treasures from the deep. Tangled masses are rolled about on

the sand}*1 shores, composed largely of Hydrallmania falcata, I4nn., Seriularia abietina, Iyinn., Eudendrium ramosum, I/inn.,

various species of Flustra and Crista, Vesicularia spinosa, T^inn., and heaps of other smaller forms along with them or growing upon them, the whole forming a very rich and easily obtained harvest. On the west coast, however, I have never found any of the species mentioned above washed ashore. It has often been disappointing upon going to some strand, where, under

similar conditions along the east coast, I should have obtained in a few minutes thirty or forty different species of zoophytes, to find practically nothing. Tullan Strand, extending a dis

tance of nearly two miles from the Fairy Bridge to the mouth A2




of the river Erne, was a good example. Even after a consider able storm during the night there was nothing washed ashore to rejoice the collector. The Rev. W. S. Green, to whom I have remarked this difference, considers that it may be largely due to the fact that on the east coast the greater amount of

trawling in the deeper parts disturbs and tears up the objects

growing upon the sea-bottom, and then during storms they are washed up on the shore.

The limestone forming the cliffs is very fossiliferous, this

feature attracting even the most casual observer. The rock seems in parts entirely made up of crinoid stems, some oi them exceptionally large in diameter. Other portions are almost entirely composed of Productus giganteus, while various fossil corals are in many places important components of the rock. In the limestone on the north side of Rogy Bay, towards Aughrus Point, the rock-pools are mostly deep vertical hollows, always full of water, and crowded at the surface with a great variety of red, brown, and green sea

weeds. On pulling these aside one is rewarded with a most

lovely sight of variously and richly-coloured sea-anemones,

covering the sides and. crevices of the rock. Especially abundant were

" the Orange Disc Anemone," and

" the

Snowy Anemone," now both regarded as varieties oi'Heliactu

venusta, Gosse; also Bunodes gemmacetis, E* and S., and in the darker corners large specimens of Tealia crassicornis, Mull

A few examples of Aplysia punctata, Cuv. were obtained here also in the shallower pools.

The rocks from Aughrus Point to the Fairy Bridge are toe

precipitous for any work to be done upon them ; but in the latter place one can easily collect along the base at low water

and also enter the Cathedral Cave near. We found -this.

exposed to the full force of the waters of the bay, to be an extremely rich locality. The sand-tubes of Sabellam

aheolata, I^inn. form, with the rocks, small hollows in whiel are little forests of zoophytes, such as Tubularia larynx^ E. and

S., Obelia flabellaia, Hincks, Campanularia flexuosa, Hincks and Plumularia setacea, Ell., and numerous smaller forms

growing upon these. Here was obtained the rare Halecium

tenellum, Hincks, the first undoubted record for Ireland, The surface of the rock also serves for the attachment oi

crowds of Mytilus edulis, I/inn., and a search amongst these



The liock-pools of Bundoran. 5

well rewarded us. On one of the ledges overhanging a pool, on the floor of which were abundant Plaice, almost undistin

guishable from their resemblance to the colour of the sand, we came across hundreds of the lovely Meiridium {Actinoloba) dianthus, Ell., of the brown and white varieties. Exposed at

low water they hung vertically almost like so many shapeless masses of mucus, each with a drop of water at the distal end,

Iyooping about amongst the Hydroids were numbers of the

Amphipod Caprella linearis, lyinn. Tubularia larynx, E- and S., was especially the home of the Nudibranch Bolts coronata,

Forbes, its rosy hues harmonising well with the light red

colour of the polypites. From the Fairy Bridge, Tullan Strand stretches for nearly

a couple of miles to the mouth of the Erne, and yielded very little to us, but the sand-hills overlooking it would well repay the entomologist. The shore towards Itildoney Point we

found unproductive, and then took our way to Coolmore, a

place from which accounts of collections in other branches

have already appeared in this Journal. Descending the Blue

Stairs we were disappointed to find the shore composed

largely of sandstone and limestone boulders derived from the

cliffs, and presenting a very meagre fauna. Going a little to

the south-west, however, we were again amongst the lime

stone rock-pools with a great abundance of life. The con

trast was most striking. Where the rocks were principally sandstone they presented quite a barren aspect, and life

appeared impoverished, while a few yards further when we

got on to the limestone, the rock-pools were replete with a

luxuriance of animal and plant life, much as we had found

west of Bundoran.

Dredging in Donegal Bay with the trawlers did not yield us

much* The bottom consists principally of sand, and the

dredge and trawl brought up little of what the fishermen

regard as refuse, but to the zoologist is a harvest. A day was

spent on the east coast of the promontory stretching between

M'Swyue's Bay and Inver Bay* Here the shore was again rich in deep vertical rock-pools filled with weeds, such as

Fucus, Laminaria, Ulva, Enteromorpha, Bryopsis, Codiunt,

Cladophora, Chondrus crisptis, Rhodymeniay Corallina offi

cinalis', Lithotkamnion polymorphum, and other rarer forms.

Hundreds of Metridmm (Actinoloba) dianthusyEU-> hung from




the under surface of projecting ledges, and most of the other common forms of sea-anemones flourished luxuriously, sharing the decoration of the pools with numerous brightly coloured sponges. Trawling around the shore our boatmen discovered for themselves a rich locality for Sole, Plaice, and Brill. The Laminaria brought up was coated with miniature forests of Obelia geniculaia, Iînn. and other zoophytes.

Numbers of shells of Pccten maximus, I4nu. were obtained encrusted with various Polyzoa. In returning across the bay

we were alarmed by the proximity of four or ^n^ large cetaceans following the shoals of herring along with flocks of

gulls. From the rounded head, large, high dorsal fin,, and

white uuder-surface, there is no doubt that they were speci mens of the Killer Whale (Orca gladiator, Iâcpa). In a small

interesting book on Ballyshauuou1 containing a chapter on its

Zoology and Botany, it is recorded that in the last century whales were so numerous in Donegal Bay that a whale-fishery was established, but owing to the general roughness of the sea it was unsuccessful, although aided by a grant of 500 from the Irish Parliament in 1736, and a grant of 1,500

1111763. We left Bundoran and its rock-pools feeling that our time

had been most profitably spent, and bearing away representa tives of many of its marine treasures preserved in our jars for future study. A more detailed list and description of these

Will shortly be published. Mr. Welch, of Belfast, has kindly allowed a reproduction of

one of his splendid series of photographs of the shores at

Bundoran. The portion represented on the accompanying

plate (Plate 1) is one of the rock-pools from which the water

has been removed. At the bottom are seen many examples of the Purple Sea-urchin {Strongylocentrohis lividus, Iâmk.)

bristling with spines, but all more or less sunk in their self

made hollows, and in some cases with dead shells upon them.

The pink-coloured " Nullipore," Lithothamnionpolymorphtm,

coats the remainder of the bottom, and especially in the narrow

ridges between the hollows rises into irregular botryoidal

masses, often tending to enclose the sea-urchins. To the left

of the plate are seen luxuriant bunches of another calcareous

Âllinghani: Ballyshannon, its History and Antiquities, Londonderry,

1879,



The Rock-pools of Btmdoratu y

ted alga, Cotatlina officinalis. Along the side of the pool ^re agglutinated masses of sand and fragments of shells

presenting the appearance of a honeycomb, each aperture being that of a tube, in which dwells the worm Sabellaria alveolate

I^inn. The limestone ledges above the pool (to the right) are quite light in colour owing to the great abundance, of

the common acorn-shell, Balanus. Numerous conical shapefl

limpets, Patella vulgata, Iyinn. are here present resting in the Shallow scars excavated by themselves. It has lately been showni that the limpets quit their homes in search of food

chiefly as the tide leaves them and when it is returning,, the extent of their peregrinations being evidently limited to adiSr tance of between one and two feet. Many of the limpets ^y# the exterior of their shells coated with Lithoihamnioti p?ly$

morfikum. Scattered about are also numerous specimensiof the spindle-shaped Purpura lapillus, I4mi.

THE DISTRIBUTION OF THE CHARACEiS IN IRELAND.

BY II. AND J, GROVES, tfX.S.

Tto large stretches of comparatively shallow water and;the many peat-bogs render Ireland a particularly favourable

country for the growth of Chamcea?, an4t although a consi4er|ble

extent; remains almost unexplored and but little has^i^n';;

thoroughly searched, the Chara Flora as at present known is

a rich one* During the past year another species, C canescens,

has been discovered, and there is little doubt that when the

Southern and Western districts have been more completely worked several others will be added to the list.

Every piece of water should be searched, as Charaf&Qgqqt in rivers and streams as well as in the lakes, pools, pitsf and

ditches, which are their more usual habitats. We ^pl4;

especially recommend examining small loughs and pools near

the sea, as likely to yield new species to Ireland. It is never

safe to assume that there is no Chara in any piece of water

until it has been dragged all over, as oftentimes they occur in

only one part and are not visible from the shore.

^ Nature^ vol. aqqri., p. 200, and vol 11, p. 127*



Irish

Nattraust, Vot,.

IV.] [Pi, ate t.

A ROCK-POOL AT BUNDORAN, Purple Sea-Urchins {Sfrongyheentrotus livid us) in their burrows.

From a Photograph by Mr. A*. \Vdch.\



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