480 NATURAL HISTORY OF HAWAII. 



they so very seldom reach the sea-shore that their presence in the islands would 

 be unknown 1iut foi- th(^ work of such expeditions as that of the Albatross. 



Jellyfish. 



Those who have been boating on the beautiful Peai-1 Harbor lochs are 

 almost sure to have seen large numbers of the curious swimming-bells of the 

 jellyfish •^•'' floating gracefully about through the water. If one is captured it 

 will sting the hands like a nettle. For this i-eason the pololia. as it is known 

 to the Hawaiian fishermen, is let severely alone by those who have once expe- 

 rienced the stinging, itching sensation, which is the result of a poison injected 

 by myriads of little stinging cells. These stinging cells or lasso cells are 

 common to many forms of Coelenterata, and are very effective in protecting these 

 apparently helpless animals from their enemies. Other species of large jelly- 

 fish are occasionally seen as they slowly swim at the surface of the ocean, or are 

 rarelv found stranded on the shore bv the receding tide, but not more than a half 

 dozen species all told ai'e known from tlie islands. 



Hydroids. 



The Hi/(]n))n( (Instep resemble the members of the foregoing family, differing 

 mainly in being smaller in size, and in the fact that the medusie or heads found 

 floating at the surface, in most cases, are in reality budded off from small 

 animals,-"'*"' which form colonies and are permanently fixed at the bottom of the 

 sea. The young medusa^ after leaving the hydroids or stems, begin an indepen- 

 dent free-swimming career. In the course of growth they pass through a 

 series of stages and finally become sexually adult. The eggs of the female 

 medusa do not, as a rule, develop into meduste. ])ut into hydroids, so that there 

 is an alteration of generations. As the hydroids seldom grow in water more 

 than a few hundred fathoms deep, the medusip are usually found in shallow 

 water offshore, though there are pelagic forms that are exceptions to the rule. 

 Only a few species of the free-swimming forms have so far been reported from 

 Hawaii. The common form.-'^' a new species, is a very small bell-shaped animal 

 with from twelve to foui'teen lash-like tentacles suspended from the edge of 

 the bell. 



Dr. Nutting visited the Hawaiian Islands on the cruise of the Albatross, 

 and subsequently devoted much time to a study of the hydroids collected 

 about the islands. He found the fauna very rich, varied and interesting, but 

 as the material examined was that secured in water from ten to five hundred 

 fathoms deep, the littoral fauna is yet to be studied. His list enumerates fort.v- 

 nine species, twenty-nine of them proving new. As the species are placed in 

 twenty-seven genera belonging to eleven families, the great variation in the 

 forms will be apparent. The shore species are often called moss animals,^'^ 

 since many of them ai-e pretty feathery, i)luni('-like creatures, so closely re- 



s''' Sryphomediisa'. ^6 Zo<)jtl;ytp/i or Hi/dr'iidx. ^' Soliiinris irisculiitii. 

 »" This name is more properly applied to the Polyzoa. 



