Halobates

Abstract: Among the million or so insect species known, only a few thousand are found in marine habitats. The genus Halobates is almost exclusively marine and is unique in having the only known species to live in the open ocean. Of the 46 Halobates species described, only five are completely oceanic in habitat, with the majority of species living in coastal areas associated with mangroves or other marine plants. This review presents a brief historical account of the genus and provides information on various aspects of its life history, ecology, special adaptations, distribution, and biogeography. Distribution maps of the five oceanic species as well as several of the more widely distributed coastal species have been updated. The phylogeny and evolution of Halobates based on morphology and recent molecular data are also discussed. A key to all known species of Halobates and related genera and a checklist of all species and their distributions are included as appendices.

Abstract: Author(s): Cheng, Lanna | Abstract: Until about 10 years ago Halobates was probably known to only a handful of entomologists; outside this segment of the entomological world it was generally unknown. However, during the last 10 years there has been a great deal of research on various aspects of the biology of this unique insect genus. It has now become a well-known organism among marine biologists; ironically though, it is still not well-known among entomologists. Recent findings on this unique genus of insects are reviewed, with additional information from unpublished personal observations.

Abstract: Relatively few insects have invaded the marine environment, and only five species of sea skaters, Halobates Eschscholtz (Hemiptera: Gerridae), have successfully colonized the surface of the open ocean. All five species occur in the Pacific Ocean, H. germanus White also occurs in the Indian Ocean, whereas H. micans Esch- scholtz is the only species found in the Atlantic Ocean. We sequenced a 780 bp long region of the mitochondrial cytochrome oxidase subunit I gene (COI) for a total of 66 specimens of the five oceanic Halobates species. Our purpose was to investigate the genetic variation within species and estimate the amount of gene flow between populations. We defined 27 haplotypes for H. micans and found that haplotype lineages from each of the major oceans occupied by this species are significantly different, having sequences containing five to seven unique base substitutions. We conclude that gene flow between populations of H. micans inhabiting the Atlantic, Pacific, and Indian Ocean is limited and hypothesize that these populations have been separated for 1 to 3 million years. Similarly, there may be limited gene flow between H. germanus populations found in the Pacific and Indian Ocean and between H. sericeus populations inhabiting the northern and southern parts of the Pacific Ocean. Finally, we discuss our findings in relation to recent hypotheses about the influence of oceanic diffusion on the distribution and population structure of oceanic Halobates spp.

Abstract: TRACHAETE arthropods, notably insects, are almost totally absent from the open ocean for various reasons which are still largely speculative1–3. Halobates (Heteroptera) is an exceptional insect genus which is exclusively marine, with several open-ocean species that spend their entire lives thousands of miles away from land. It is a member of the family Gerridae, which includes the common pond-skaters or water-striders. Although species of Halobates have been known for more than 150 yr, there is little information about their biology and about specific adaptations which might enable them to live in the oceans where all other insects have failed4.