322 OUT OF DOORS. 



Calm and peaceful as is the grotto, it can at once be 

 transformed into a scene of the wildest excitement. At 

 a sign from Mr. Lloyd an attendant disappears, and 

 presently a shadow is seen on the surface of the water, 

 and a small white object — a morsel of whelk — falls from 

 the shadow, and sinks slowly through the water. At 

 first no notice is taken, but in a second or two a prawn 

 leisurely crosses the track of the still sinking morsel. 

 Instantly it scents its food, starts into sudden activity, 

 and follows on the scent just as a hound follows a fox. 

 Another and another succeed, and it is remarkable that 

 while the prawns seem to let the food pass before their 

 eyes without taking any particular notice of it, no 

 sooner do they perceive the scent of the water through 

 which it has sunk than they are after it at once. Now 

 comes a whole shower of chopped whelk or mussel, and 

 in a few seconds the tank is filled with prawns, all in 

 busy excitement, some tucking up, or rather, down, 

 their food, and others carrying ofi" the white morsels 

 to a quiet resting-place where they can eat in peace. 

 Much the same habit distinguishes the whelks them- 

 selves and other carnivorous molluscs, which can be 

 allured out of their retreats by trailing a morsel of 

 food near them. They do not see the food, but they 

 smell it, and forthwith set off in search of the expected 

 banquet. 



The reader will have probably remarked that we have 

 only noticed a few of those marine animals who act as 

 food. There are plenty of others, including the 



