Adaptations to Environment 119 



tition but all the endeavours which secure the welfare of the 

 offspring, and give them a good send-off in life. So it is without 

 a jolt that we pass from struggle for food and foothold to 

 parental care. The marine leech called Pontobdella, an interest- 

 ing greenish warty creature fond of fixing itself to skate, places 

 its egg-cocoons in the empty shell of a bivalve mollusc, and guards 

 them for weeks, removing any mud that might injure their 

 development. We have seen a British starfish with its fully- 

 formed young ones creeping about on its body, though the usual 

 mode of development for shore starfishes is that the young ones 

 pass through a free-swimming larval period in the open water. 

 The father sea-spider carries about the eggs attached to two of 

 his limbs; the father sea-horse puts his mate's eggs into his breast 

 pocket and carries them there in safety until they are hatched; 

 the father stickleback of the shore-pools makes a seaweed nest 

 and guards the eggs which his wives are induced to lay there; 

 the father lump sucker mounts guard over the bunch of pinkish 

 eggs which his mate has laid in a nook of a rocky shore-pool, and 

 drives off intruders with zest. He also aerates the developing 

 e gg s by frequent paddling with his pectoral fins and tail, as the 

 Scots name Cock-paidle probably suggests. It is interesting that 

 the salient examples of parental care in the shore-haunt are mostly 

 on the male parent's side. But there is maternal virtue as well. 

 The fauna of the shore is remarkably representative from 

 unicellular Protozoa to birds like the oyster-catcher and mammals 

 like the seals. Almost all the great groups of animals have ap- 

 parently served an apprenticeship in the shore-hunt, and since les- 

 sons learned for millions of years sink in and become organically 

 enregistered, it is justifiable to look to the shore as a great school 

 in which were gained racial qualities of endurance, patience, and 



alertness. 



II. THE OPEN SEA 



In great contrast to the narrow, crowded, difficult conditions 

 of the shore-haunt (littoral area) are the spacious, bountiful, and 



