Among millions of insect species known in the world only five species of Halobates (Heteroptera: Gerridae) are able to live in the high seas. The general public is probably not aware that there are insects living on the open ocean and even most marine scientists have never seen a live or preserved specimen with their own eyes. The genus Halobates was first collected during a Russian oceanographic expedition around the world between 1815 and 1818.

The sea-skater Halobates was collected in eastern Indonesian waters during the SNELLIUS II Expedition in August 1984 (SE monsoon) and February/March 1985 (NW monsoon).  About 200 specimens were caught in 18 tows at offshore sites in August, in the upwelling season, but more than 1,000 in 18 tows in February, when the mixed layer was nutrient depletedand chlorophyll-poor. The Indo-Pacific species H. germanus predominated in thecatches during both cruises, its density being inversely related to surface chlorophyll concentration.  Reproductive activity of H. germanus was highest in oligotrophic conditions, the relative abundances of nymphs and of cast skins being much higher in February than inAugust. Shifts in the population structure in February suggested a development time of about 7 days or less per stadium at a surface seawater temperature of 29°C. The cosmopolitan H. micans and the coastal H. flaviventris and H. princeps were absent or rare in August but present in most catches in February; some specimens of the latter two species were found at stations more than 150 km from the nearest shore.