November 28, 191 2] 



NATURE 



6/ 



MINUTE LIFE ON OUR SEA-BEACHES.'^ 



IK thinking of a suitable subject on which to 

 address j'ou this evening, it naturally occurred to 

 me that the fellows of the Linnean Society and their 

 friends include both botanists and zoologists, and are 

 all of them, I hope, good field naturalists, who delight in 

 work in the open. So I have decided to talk about 



Fig. I. — .\ Lancashire mussel skear. 



what I am coming to regard as a somewhat neglected 

 field of investigation, namely the minute life of our 

 ordinary sea-beaches and the changes which that life 

 undergoes throughout the year. Many biologists are 

 inclined to regard an ordinary sandy beach as a very 

 uninteresting collecting ground, where, they would 

 say, there are but few living things to be found — per- 

 haps some burrowing worms, such as Arenicola, some 

 heart-shaped urchins, like Echinocardium, some 

 lamellibranch molluscs, Solen, Mya and the 

 cockles, and that is about all that most collectors 

 would bring back from such a beach ; and we 

 have all heard fishery experts exclaiming at the 

 poverty of such coasts in eloquent words. "Oh, 

 the barren, barren shores which might be culti- 

 vated so richly ! " is the burden of their cry. 

 There is some truth in it. But if I am able to 

 show that they are not so barren as is supposed, 

 that only makes it the more likely that the 

 beaches might be cultivated with advantage for 

 the benefit of man. 



The amount of living things, both plants and 

 animals, that can grow or may be reared in suit- 

 able localities between tide marks is astonishing. 

 Let me show you a few photographs exhibiting 

 life in profusion, both in its natural wild state 

 and also under artificial cultivation, as examples 

 of characteristic views on our coasts. Some show 

 patches of the littoral zone near low tide mark, 

 with in some cases huge colonies of the fleshy t'i 

 coral Alcyonium, and numbers of sea-anemones, 

 of worm-tubes, and of zoophytes ; in other 

 cases masses of the larger algae, Fucus and 

 Laminaria; and then again some have the molluscs. 

 Patella, Purpura, and Littorina, covering almost every 

 available inch of the ground. Other more rocky shores, 

 such as Bradda Head at the south end of the Isle 

 of Man, have the stone so closely infested with 



le T.innean Society's Reception on October 31 by 



Balanus, the acorn-shell, that for hundreds of yards 

 it looks at low tide, from a distance, as if a broad, 

 uninterrupted horizontal band of white had been 

 painted on the rock, and on going close up to such a 

 cliff one sees that for many yards in succession it is 

 difficult to find a spot of exposed stone on which to 

 put a finger. 



Then, as an example of what could be done by 

 cultivation, even of the rudest kind, we 

 may look at these photographs of the 

 mussel skears on some parts of the coast 

 of Lancashire (see Fig. i), where the 

 shellfish soon become so closely crowded 

 that, unless thinned out, they prevent 

 each other's growth by their mutual 

 pressure. 



These organisms, however, are all 

 large, common, and well known, while 

 what I desire to bring before you as a 

 neglected field is the presence of minute 

 and little-known organisms which appear 

 in profusion in some localities, at any 

 rate on certain occasions, and are prob- 

 ably of enormous importance in their 

 influence on the life of larger forms, 

 both on the shore and at sea. Probably 

 many, if not all, seashores would show 

 the phenomena I wish to refer to, but 

 the beach which I take as my example is 

 that at Port Erin, in the Isle of Man, 

 where between two rocky sides there is 

 a flat expanse of sand with the usual 

 barren appearance, and the usual bur- 

 rowing annelids and molluscs. 

 The sandy beach has a steeper slope in its upper 

 part, and at the base of this, not very far below high- 

 water mark, and just where the damper, flatter, and 

 less stony part of the sand commences, there are found 

 from time to time throughout the greater part of the 

 year larger or smaller greenish-brown patches, 

 sometimes yards in extent, such as most naturalists 

 would declare at a glance to be caused by 



NO. 2248, VOL. 90] 



accumulations of diatoms — and diatoms we at 

 Port Erin at first supposed them to be. But one 

 day last year on collecting a sample and putting it 

 under the microscope I w-as astonished to find that 

 the deposit W'as composed of an enormous quantitj^ 

 of minute, active, flagellate, 3'ellow organisms, 

 evidentlv belonging to the Dinoflagellata, and related 

 to Peridinium (see Figs. 2 and 3). 



