THE GROWTH OF JELLY-FISHES. 



741 



The hydra which hatches from the Qg^ of the Cunina is free, 

 like the hydra-larva of Liriope. It has a short globular body, and 

 an enormously elongated proboscis, at the tip of 

 which the mouth is situated (Fig. 10). It has four 

 short tentacles which are turned backward away 

 from the mouth, and are terminated by round 

 knobs, which are used for clinging to the body of 

 the Turritopsis, for as the parasitic larva sucks its 

 food out of the stomach of its host, it does not 

 need to use its tentacles for capturing living ani- 

 mals. As soon as it finds its way into the bell of a 

 Turritopsis it fastens itself securely by its tentacles 

 to its inner surface in the angle at the base of the 

 stomach, where it is in no danger of being swept 

 away by the current which the Turritopsis produces 

 while swimming, and, once securely fastened, it 

 bends down its long proboscis, passes it up through 

 the mouth of the Turritopsis into its stomach, and 

 sucks out the digested food. 



Turritopsis is shown at K in Fig. 15 ; and Fig. 11, 

 which I have copied from McCrady, the discoverer 

 of this remarkable case of parasitism, shows the 

 outline of the inner surface of the bell, and of the 

 stomach of Turri- 

 topsis, with three 

 of the parasitic 

 Cunina larvse in 

 place, fastened by 

 their tentacles, 

 and with their 

 mouths inserted 

 into the stomach 

 of their host. 



Thus protect- 

 ed by the bell, 

 and supplied with 

 abundant food, 

 which it neither 

 captures nor di- 

 gests, but sucks, 

 all ready for as- 

 similation, into its own stomach, the larva has a very "soft 

 thing,^^ and is naturally in no hurry to complete its development 

 or to seek its fortune in the open water. It grows rapidly, ac- 

 quires more tentacles, and, as its stomach grows larger, and it 

 becomes able to suck in and to assimilate more food than it needs 



Fia. 10. 



The Hydra, which hatches from the ege of Cunina ocionaria, 

 drawn from nature by W. K. Brooks : o, body ; p, month ; /, 

 tentacles. 



