272 



THE INHABITANTS OF THE SEA. 



Poulp (Octopus). 



orders, Octopods and Decapods, the former having only eight 



sessile feet, while the latter possess 

 an additional pair of elongated ten- 

 tacles, which serve to seize a prey 

 that may be beyond the reach of 

 the ordinary feet, and also to act as 

 anchors to moor them in safety during 

 the agitations of a stormy sea. 



Both the arms and tentacles are 

 furnished with suckers disposed along 

 the whole extent of the inner surface 

 of the former, but generally confined 

 to the widened extremities of the 

 latter, where they are closely aggre- 

 gated on the inner aspect. 



In all the octopods the suckers are 

 soft and unarmed. Every sucker is 

 composed of a circular adhesive disk, which has a thick fleshy 



circumference and bundles of mus- 

 cular fibres radiating towards the 

 circular orifice of an inner cavity. 

 This widens as it descends, and 

 contains a cone of soft substance, 

 rising from the bottom of the cavity, 

 like the piston of a syringe. When 

 the sucker is applied to a surface 

 for the purpose of adhesion, the 

 piston, havingpreviously been raised 

 so as to fill the cavity, is retracted, 

 and a vacuum produced, which may 

 be still further increased by the 

 retraction of the plicated central 

 portion of the disk. So admirably 

 are these air-pumps constructed, and 

 so tenacious is their grasp, that, 

 when they have once seized or fixed 

 upon a prey, it cannot possibly dis- 

 engage itself from their murderous 

 Caiamary. embrace. 



In many of the decapods, who, generally seeking their prey in 



