Zooplankton of the Atlantic and Gulf Coasts: A Guide to Their Identification and Ecology

Sea Spiders, Mites, and Insects

SEA SPIDERS, MITES, AND INSECTS This section contains two groups of primarily benthic arthropods that are occasionally swept off the bottom and then caught in plankton samples plus insects often incidentally collected at the water’s surface. These animals are particularly common in saltmarsh creeks and other shallow inshore habitats. SEA SPIDERS (PYCNOGONIDS) Sea spiders occur in high-salinity areas throughout our range, especially in saltmarsh creeks or on hard substrates such as docks, jetties, or oyster reefs. These bizarre-looking, eight-legged creatures are usually associated with hydroids or benthic fouling communities . Although they are not true spiders, pycnogonids resemble spiders sufficiently to make them recognizable. MARINE MITES (FAMILY HYDRACHNIDAE) The mites resemble diminutive (<2 mm) seagoing ticks. Unlike most terrestrial mites, the most common marine mites are predators on minute organisms rather than parasites. INCIDENTAL INSECTS Most insects in plankton collections are terrestrial insects that happened into the net before sampling. However, flying insects sometimes land on the surface film and are caught as nets are deployed or retrieved. Among the more common insects are various dipterans and their larvae. We show an adult ceratopogonid, one of the more common biting “nosee -ems,” or gnats, found on salt marshes. Midge (chironomid) larvae are swept into the plankton on occasion. SEA SPIDERS, MITES, AND INSECTS 265 pycnogonid or sea spider marine mite winged insect 1 mm 100 µm 1 mm 266 IDENTIFICATION AND BIOLOGY OF COMMON ZOOPLANKTON SUGGESTED READINGS Biology and Identification References Arnaud, F., Bamber, R. N. 1987. The biology of Pycnogonida. Advances in Marine Biology 24:1–96. Child, C. A. 1992. Shallow-water Pycnogonida of the Gulf of Mexico. Memoirs of the Hourglass Cruises 9(1):1–86. McCafferty, W. P. 1998. Aquatic Entomology: The Fisherman’s and Ecologist’s Illustrated Guide to Insects and Their Relatives. Jones & Bartlett, Boston. 448 pp. (Information on identification and the biology of marine mites and midge larvae.) McCloskey, L. R. 1973. Marine Flora and Fauna of the Northeastern United States: Pycnogonida. NOAA Technical Report NMFS Circular 386. 12 pp. Newell, I. M. 1947. A systematic and ecological study of the Halicaridae of eastern North America. Bulletin of the Bingham Oceanographic Collection 10:1–266. Weiss, H. M. 1995. Marine Animals of Southern New England and New York. State Geological and Natural History Survey of Connecticut, Department of Environmental Protection, Hartford. 344 pp. (Contains an illustrated guide to identification of marsh and beach insects and to sea spiders, with some notes on ecology and habitat.) ...