Hawaiian salt water gerride
Location: Maui west side
March 7, 2011 10:49 pm
These striders are out in the waves of the Lahaina area. I only see them in smooth water, they go somewhere else when the wind comes up. Those back fins are used for speed, I have not been able to get a photo of a live one. It looks like they can dive under water, but I’m not positive since they are so fast they seem to disappear. Is there an ID for ocean striders?
Signature: w
Dear w,
Thanks for sending these photos of Pelagic Water Striders found in the open ocean. Your observations are quite informative. We have located an online pdf originally published in 1937 entitled “Biological Notes on the Pelagic Water Striders (Halobates) of the Hawaiian Islands, with Description of a New Species from Waikiki (Gerridae, Hemiptera).” The article identifies the pelagic species Halobates sericeus and indicates another species Halobates hawaiiensis, which is found closer to shore, apparently in calmer waters. Here is an excerpt from this published paper by ROBERT I. USINGER : “The reputed diving ability of these bugs is a subject of considerable controversy. Thus Murray,3 Walker,4 and Henry5 state positively that these bugs dive beneath the surface, while Hay6 and Delsman7 were unable, under any circumstances, to induce them to dive. My own observations are as follows. Neither in captivity nor under natural conditions was I ever able to force Halobates nymphs or adults to dive beneath the surface. In Micronesia I have stood in shallow water amidst many thousands of these bugs and have tried in every way to frighten them or force them to dive. They jump frequently and may move in this way so quickly that they seem to disappear. On the other hand I took a glass plate and forced a number of individuals a foot or two below the surface, holding them there to observe their actions. They were able to swim with very jerky, awkward movements first downward, thence out beyond the edge of the glass and up toward the surface where they quickly broke through the surface film to freedom.” BugGuide indicates that the genus Halobates contains: “The only true marine insects. Can be found in the open ocean“, but BugGuide does not have any images.
