32 



Table 7. Number of reported species of the superfamily Phronimoidea inhabiting different 

 depths in the Canary Islands regions' (from Thurston, 1976b) 



Depth, m 



Number of species 



% 



of total number 



Number of recurrent 





found 





of species 



species 



0-200 



16 





100 



16 



200-500 



7 





44 







500-750 



5 





31 







750-1,000 



3 





19 







' Sixteen species are considered, for which more than two specimens were found. The 

 results of diurnal and noactumal catches have been combined. 



few species have obligate links with specific deepwater medusae. Thus, 

 one of the most deepwater Phronimoidea — Hyperia spinigera, associated 

 in the North Atlantic with the medusa Periphylla periphylla — inhabits 

 mostly depths of 600-900 m (Thurston, 1977). In the Sea of Japan the 

 population of Parathemisto japonica inhabits not only surface and inter- 

 mediate waters, but penetrates to depths of 2,000-3,000 m, which in this 

 basin comprise cold subsurface waters (Vinogradov and Sazhin, 1978). 



Unlike epipelagic species, usually distributed circumtropically, most 

 species with a wider range of vertical distribution have either a 

 panoceanic range or their range is confined to temperate-cold-water and 

 cold-water oceanic regions. Thus, in the family Hyperiidae only the genus 

 Hyperiella and the species Hyperia macrocephala are adapted to waters 

 of the high Antarctic latitudes. Only species of the genus Parathemisto 

 (subgenus Euthemisto) inhabit the coldest waters of both hemispheres. 

 At the same time, among eurybathic species, some have adapted to warm 

 waters {Hyperia leptura, Hyperoche mediterranea, H. picta) or even to 

 tropical regions {Hyperia crassa, H. bowmani, Hyperoche martinezi). But 

 these are less numerous, even rare species, known from a few specimens. 



Eurybathic members of the families Phronimidae {Phronima 

 atlantica, P. sedentaria) and Phrosinidae {Primno niacropa) on the other 

 hand, are widely distributed, inhabiting tropical and temperate-cold-water 

 regions of the oceans. With respect to population density, they occupy 

 first place among hyperiideans of the mesopelagic (200-800 m). 



Special mention must be made of the lone representative of the aber- 

 rant genus Bougisia of the family Hyperiidae. Judging from its structure, 

 it possibly inhabits deep waters, though it has also been found in surface 

 waters. 



Because of the above two ecological groups of species (epipelagic 

 and eurybathic), great diversity of area of distribution is characteristic of 

 this family (Table 8). But since the entire superfamily Phronimoidea is 



