Introduction

Since 1954, a marine research team led by Professor L. R. Richardson has investigated the benthic and pelagic fauna of Cook Strait to depths in excess of 1,000 fathoms, and of Wellington Harbour. Analysis of benthic samples revealed 235 specimens of holothurians, which represent eleven genera and eleven species, of which four species are new records for the area. In addition, there are four more species, also known from Cook Strait, but not represented in the collections. These are diagnosed and briefly discussed here.

Throughout this report, the Cook Strait region is taken to comprise Cook Strait including Palliser Bay, and Wellington Harbour.

Farquhar (1898) recorded seven valid holothurian species from the Cook Strait region. Mortensen (1925) later added four species, bringing the total to eleven. No further records were made between 1925 and the present time. It is probable that the list of species is still far from complete; the shelf fauna is as yet imperfectly known, and deeper waters should yield many more species.

Perhaps the only Cook Strait holothurian to attract the attention of the casual collector is Stichopus mollis (Hutton), known locally as the "brown sea squirt" or "sea sausage". It is by far the largest and most common shallow water form. Other intertidal species are rather more secretive in their habits, and may be found only by assiduous digging and overturning of rocks in sandy or muddy pools. The apodous species Trochodota dunedinensis (Parker) frequently inhabits tufts of the red alga Corallina. Dendy (1898) noted that the dentrochirote Ocnus calcareus occurs ". . . . not uncommonly on seaweed in Cook Straits near Wellington, where it may be collected at lowtide". Beyond the intertidal zone, the shelf and deep water species may be taken by dredging and trawling.

I am grateful to Professor H. B. Fell of this department for his careful guidance and constructive criticism throughout the course of this study. My thanks are also due to Professor L. R. Richardson for access to collections and for many valuable suggestions and discussions, and to Mr J. W. Brodie, Director of the New Zealand Oceanographic Institute, for making available to me specimens of Heteromolpadia marenzelleri (Theel) and Paracaudina chilensis (Muller).