418 EIGHTH PACIFIC SCIENCE CONGRESS 



The Holothurian Fauna of the Different Provinces 



OF THE InDO-PaCIFIC OcEAN 



Table I lists many of the known littoral holothurians reported 

 from the different provinces of the Indo-Pacific Ocean. The Indo-West- 

 Pacific area has related and almost identical species of Holothurioidea. 

 The explanation of the close relationship and similarities of the aspi- 

 dochirote holothurian fauna of this particular area is the proximity of 

 the different provinces with their continental shelves almost connecting 

 with one another. The Indo-Malayan region (Indian Ocean, West 

 Pacific and Southwest Pacific provinces) has its faunistic centre in the 

 Malay Archipelago. The Indo-Malay Archipelago is the world's great- 

 est archipelago containing large water areas less than 200 meters in 

 depth. There is no other region in the world richer in species than 

 this particular area, and it is considered to be the "hotbed" of echino- 

 derms including all other marine life. Farther eastward the number 

 of known species of Holothurioidea lessens due apparently to the ab- 

 sence of more records of species from the place. Various investigators 

 report that the marine life toward the east is poor compared with that 

 of the westward side of the Pacific, although others believe the contrary 

 with regard to fishes. One of the reasons advanced for this finding is 

 the direction of the main currents, which are from east to west. 



The Hawaiian echinoderm fauna, according to H. L. Clark and 

 W. K. Fisher, is closely related and identical to those of the isolated 

 oceanic islands the farther to the east they are situated. The affinity 

 of Hawaii's fauna with the American shelf fauna, to which the fauna 

 of the Galapagos Islands belongs, is the same as with that of the Poly- 

 nesian fauna. The fauna of the Galapagos has been grouped with that 

 of Hawaii and outer Polynesia as "Eastern Polynesian" fauna. 



The tropical and partly subtropical faunistic region of Australia 

 is contrasted with a temperate one. The number of species is not as 

 large in the tropical shelf region of Australia as in the Indo-Malayan 

 region but many species are nevertheless common to both. Many spe- 

 cies of Holothurioidea are endemic in Australia, but they belong as a 

 whole to genera which are also represented in the Indo-Malayan fauna. 



The Atlanto-East-Pacific is the second great warm-water region of 

 the warm-water fauna of the shelf. Table I also lists many species of 

 holothurioidea common to both the tropical East Pacific and the West 

 Atlantic Ocean. Ekman considered the two fauna as a faunistic unit, 

 in spite of the presence of physical barrier, the isthmus of Panama. The 

 affinity between the two marine regions is shown not only by the holo- 

 thurian fauna but other marine life including the fishes. To explain 

 the close faunistic resemblance between the two coastal regions which 



