36 THE SEAS 



(Plate 15), are also inhabitants of rocky shores. They are 

 covered with spines — which in allied animals from warmer 

 seas may be of great length and, sometimes, thickness — 

 and must be handled carefully. 



Some shore fishes can alwavs be found under stones. 

 The most common is probably the butterfish (Centronotus 

 gunellus), about six inches long, eel-like, flattened from side 

 to side and with nine or more dark spots edged with yellow 

 down the middle of the back. The smooth blenny (Blennius 

 pholis) (Plate 8), can withstand long periods out of water 

 and is common on the shore, as are the bullhead or father- 

 lasher (Cottus bubalis), with its large head armed with 

 four formidable spines, the five-bearded rockling (Motella 

 mustela) to be recognized by the five barbels under its 

 snout, and various kinds of sucker-fish [Lep ado g aster), 

 whose hinder (pelvic) fins are united to form a sucker by 

 means of which the fish fastens itself to rocks. 



In holes and cracks in rock live worms of various kinds, 

 also a quaint crustacean called Gnathia and the little sea 

 gherkins (Cucumaria), which can frequently only be removed 

 by splitting the rock with a crowbar. Here, too, are rock- 

 boring bivalves, especially the common Saxicava, though 

 the large " Piddock " (Pholas) and some of its smaller 

 allies are common in some parts. 



There is no more fascinating or more beautiful spot on 

 the shore than a typical rock pool. Its sides and bottom 

 are usually covered with a many-coloured carpet of weeds, 

 sponges, hydroids, sea mats and sea squirts, amongst which, 

 like flowers, glow the rich colours of anemones (Plate 16). 

 The commonest of these — by no means confined to the pools 

 but common on the higher parts of shore — is the beadlet 

 (Actinia), usually a deep red or brown, but sometimes red 

 with green spots (the strawberry variety) or, less frequently, 

 a bright green. At the base of the tentacles is a row of blue 



