244 



THE BIOLOGY OF MARINE ANIMALS 



Finally we may note a few examples of sedentary benthic forms which 

 lie and wait for prey to approach. Perhaps the best-known is the angler-fish 

 Lophius piscatorius, which simulates the bottom on which it lies remarkably 

 closely in shade and pattern. The first dorsal spine of the angler consists of 

 a movable spine with a bait-like tag at the end, and this can be erected as a 

 fishing lure. When a fish is attracted by the lure, this is cast down in front 

 of the mouth, and as the fish follows it the angler opens its mouth and 

 takes in its victim with a sudden gulp. Angler-fish feed preferably on gadoids, 

 clupeoids and other soft-finned fishes. Of a similar nature are the habits of 

 stargazers Uranoscopus. The mouths of these creatures open towards the 

 dorsal surface of the head and they bury themselves to a large extent in 

 the sand, with only the mouth and eyes at the surface. At intervals a small 



Fig. 5.29. Trigla lucerna Feeling its Way along the Sea Floor by 

 means of Long Pectoral Filaments. (From Steven (93).) 



lure is protruded from the mouth and caused to wriggle on the sand so as 

 to simulate a worm or other small invertebrate, and thus attract small 

 prey to within reach of the stargazer's jaws. The electric fish Torpedo, 

 which is an inactive benthic form, is believed to stun or kill other fish by 

 means of electric shocks. This animal captures round fishes, some of them 

 of fair size. Individuals, observed in captivity, respond only to living prey. 

 At the approach of a fish the electric ray leaps upwards and attempts to 

 envelop it with its pectoral fins and snout. Galvanometer recordings 

 obtained during this manoeuvre show that the ray discharges an electric 

 shock at the moment that it folds its head and wings over the prey. The 

 shock apparently is used to stun the prey while it is being swallowed (82, 

 104, 107). 



Marine Birds. Marine birds can be grouped into several communities : 

 as littoral species confined to shores and beaches, e.g. plover, sandpipers; 

 inshore species which do not range beyond sight of land, e.g. cormorants, 



