Fig. 15. Ncniatocysts, the stinging cells of jellyfish. 



1-3 from the small jellyfish Siinia; i, undischarged; 2 and 3, two stages of penetration; 4-6 from 



the large stinging jellyfish Cyaiica; 4, undischarged; 5, discharged; 6, as 5 but at a reduced scale 



to show the length of the thread. All after Russell, partly from the Journal of Marine Biological 



Association, and partly from The School Science Review. 



Amelia (Plate XIII and Fig. 16) sometimes called '88' because of the four 

 horseshoe shaped gonads so readily visible in its very transparent jelly. It has 

 four 'arms' hanging from the centre of the disc — the umbrella as it is called. 

 This is not a stinging jellyfish to the bather as its stinging cells are not power- 

 ful enough to penetrate the skin of even a 'fair blonde' though it does live by 

 paralysing its prey. Strangely enough when quite small, about an inch across, 

 it can paralyse and eat small fish almost its own size, but as it grows its 

 mouth capacity shrinks so that as a full grown jelly of 6 inches or i foot in 

 diameter it feeds entirely on small planktonic animals. 



The big stinger Cyaiica (Fig 16. and Plate II) — which may be a yellow- 

 brown, C. capillata, or a blue colour, C. laiiiarcki — is usually much bigger, 

 often 2 feet and occasionally nearly 3 feet. It has a thick set of very long 

 trailing tentacles which can extend in the water as much as 30 feet. These 

 are liberally provided with powerful stinging cells which can indeed be 

 unpleasant, not only to the tender skin of a bather but to the horny hands of 

 a fisherman, and extremely nasty if the eyes are affected. Big stinging 

 jellyfish nevertheless do form a protective umbrella to schools of small fish 

 about I to 2 inches long, especially young whiting and rockling. They 

 do not seem to suffer from the jellyfish and use the umbrella for a sunshade 

 on bright days; no doubt they are safer there from some of their own 

 predators and they may be feeding to some extent on 'crumbs from the jelly's 

 table', or on crustacean parasites of the jellyfish. 



51 



