. Bulletin. Science; Natural history; Natural history. 1975 MITES ON AM PHI PODS t 30 20 — 10-1 N=275 III! 0 2 4 6 8 10 12 14 16 18 "32 34 No. of mites per host Figure 3. Degree of infestation with mites of all O. coniiculata examined. The average size of the mite population on individual infested hosts increased slightly with host body size (Fig. 2). This is not surprising since larger hosts have more room for parasites, and have had a longer time in which to acquire them. One male in the largest size class carried 33 mites. Among those O. cornicidata which were infested, small mite load
. Bulletin. Science; Natural history; Natural history. 1975 MITES ON AM PHI PODS t 30 20 — 10-1 N=275 III! 0 2 4 6 8 10 12 14 16 18 "32 34 No. of mites per host Figure 3. Degree of infestation with mites of all O. coniiculata examined. The average size of the mite population on individual infested hosts increased slightly with host body size (Fig. 2). This is not surprising since larger hosts have more room for parasites, and have had a longer time in which to acquire them. One male in the largest size class carried 33 mites. Among those O. cornicidata which were infested, small mite loads were more com- mon than large loads (Fig. 3). Dislrihiition anil attachment of mites on the host body.—When live hosts were examined, unattached mites occasionally were observed crawling on the ventral or dorsal side of the host. or on its appendages. This probably explains why mites were sometimes found detached from their hosts following preservation in alcohol. Attached mites, however, when observed on hosts preserved in alcohol, were found only ven- trally on the amphipod body; here they ranged longitudinally from the area between the first gnuthopods to a position directly above the first picopods. Mites were found in every possible position on this flat, thin skinned surface, and also on sites on the five pairs of gills (Fig. 4). The ventral surface forms part of a protected and probably humid chamber when the amphipod curls its body and crosses its gnathopods and peraeopods across its ventral side during its daily resting period in its sand burrow. The number of mites on the ventral surface was greater anteriorly on the hosts while the number on the gills was higher posteriorly, where the gills are larger. In heavily infested hosts, mites tended. Ventral surfoce position E .= 40- " g 20- LL R. Gill pair Figure 4. Positions on host body at which attached mites were found in a survey of 275 amphipods. An O. cornicidata (male) is shown with appendages of the left
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