|
||
 Marine InsectsAbstract: We hope the symposium will evoke more interest in the uniqueness of marine and intertidal insect species, including the great diversity of their habitats, which range from saturated salt ponds to the open ocean. My own study of insects dates to research I conducted at the University of Singapore, where I studied a remarkable group of insects called pond skaters, known for their ability to "walk on water." Few entomologists at the time had heard of marine insects, and even fewer oceanographers were aware of such creatures living on the open ocean. When I came to Scripps, I soon discovered that there are at least a few hundred insect species belonging to many different orders that live in various marine environments. I began studying sea skaters (Halobates), a group of wingless insects that can "skate" on ocean water at a speed as fast as one meter per second.
Think of animal life in and around the oceans. Most people think of fish, whales, dolphins and sea gulls. How many people think of marine insects? For the past 30 years, I have studied this little- known but tremendously fascinating aspect of the ocean world. Insects comprise more than 75 percent of all described animal species. Some 25,000 to 30,000 insect species, about 3 percent of all insects, are aquatic, or have aquatic larval stages, and live in all sorts of watery habitats. But only relatively few are found in the sea or around seacoasts. Certain marine insects are economically or medically important. Biting midges and salt-marsh mosquitoes have prevented coastal development in several Caribbean islands and parts of Florida. They are irritating biters and may also carry infectious diseases. In many ways, marine insects have slipped through the cracks of both entomological and marine studies. One step to help shed light on this subject will take place in San Diego Dec. 12 during the annual meeting of the Entomological Society of America (ESA). For the first time, the ESA has devoted one of its major symposiums to marine insects. Together with Wyatt Hoback of the University of Nebraska, I will chair a session on insects of marine and saline habitats. It will cover a variety of topics, including insects of coastal habitats and inland salt lakes, ocean skaters, environmental effects and control of coastal mosquitoes, and health and nuisance factors associated with biting midges in southeastern United States. We hope the symposium will evoke more interest in the uniqueness of marine and intertidal insect species, including the great diversity of their habitats, which range from saturated salt ponds to the open ocean. My own study of insects dates to research I conducted at the University of Singapore, where I studied a remarkable group of insects called pond skaters, known for their ability to "walk on water." Few entomologists at the time had heard of marine insects, and even fewer oceanographers were aware of such creatures living on the open ocean. When I came to Scripps, I soon discovered that there are at least a few hundred insect species belonging to many different orders that live in various marine environments. I began studying sea skaters (Halobates), a group of wingless insects that can "skate" on ocean water at a speed as fast as one meter per second. Sea skaters feed primarily on zooplankton trapped at the sea surface, grasping their prey with their short front legs and sucking them dry. While members of the coastal species deposit their eggs on fixed materials such as mangrove tree trunks or rocks, open-ocean species lay eggs on just about anything that floats, including empty seashells, wood, feathers, seeds and even lumps of tar. Among the most interesting aspects of Halobates is how they manage to walk or skate across the surface of the ocean. The secret is the tiny water-repellent hairs on their legs and feet that allow them to "tiptoe" across the surface of the water. These hairs also help to spread the insects' weight over a larger surface area, preventing them from sinking. The surface tension of the air-sea interface allows them to stand or move on the water. As long as the surface tension is maintained, sea skaters are able to move normally. If the surface tension is lowered by pollutants or detergents, they flop on the surface and eventually sink. Even tinier hook-shaped hairs, about 1.5 microns long, also cover the sea skaters' bodies. These trap a layer of air surrounding the insect, making them buoyant. Thus, they are basically enclosed in an air bubble; if they are pushed under the water, they quickly pop up again. If sea skaters are caught in rough seas and trapped beneath the surface for short periods, this jacket of air provides them with enough oxygen to survive. Twenty-five years ago, I edited and had published the first reference book on marine insects. It remains to this day the only comprehensive book on the subject. Needless to say, there is a lot more to learn. We hope that the dozen or so scientists presenting papers on marine insects at the ESA meeting in San Diego will help generate new interest and ideas about these unique creatures. The text of the above
article originally appeared in the San Diego Union-Tribune on Nov 28,
2001. Useful websites: Marine Insects Home Page Halobates, Zoological Museum of Copenhagen, Denmark |
Marine Insects:
|
|
