Hopkins Marine Station Student Paper

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(full paper is archived in the Miller Library)

Title: Infestation of the sandy beach amphipod Orchestoidea corniculata by the mite Gammaridacarus brevisternalis (Laelaptidae)
Student Author(s): Scurlock, Donna
Faculty Advisor(s): Abbott, Donald P.
Pages: 15
Location: Final Papers Biology 175H
Date: June 1972
Keywords: sandy beaches
Abstract: 1. The mesostigmatid mite, Gammaridacarus brevisternalis has been found and identified on both decomposing beach wrack and on the beach amphipods Orchestoidea corniculata and O. californiana. 2. The percentage of infestation of the host population increases with size of host and varied from 1.5% (hosts 3 - 7.9 mm) to 83.07% (hosts 16 - 19.9 mm). Mites showed no preference for male or female hosts. The number of mites per infested host increases slighly with amphipod size. 3. Mites were found attached, either by mouth parts or posterior end, exclusively on the ventral side. 4. The mites were found to leave dead hosts within 2 - 9 hours after death. 5. Mites without hosts can crawl over sand at an average rate of 3 inches per minute. 6. Gammaridacarus brevisternalis were found, after leaving dead hosts, to attach to new, living hosts. When contact between dead and living hosts was prevented, the mites traveled up to at least 30 cm in finding new hosts. Observations suggest that the mites may posses senses for locating healthy hosts at a distance.
Notes: Publ. 1975, Bull. So. Calif. Acad. Sci. 74: 5-9