Student Research Projects
Leg Injuries in the Neotropical Harvestman Erginulus clavotibialis (Opiliones, Laniatores, Cosmetidae)
|Student||John Evans, ‘13|
|Course||BIO 489: Research in Natural Sciences|
In Belize, we collected 85 individuals of the cosmetid harvestman Erginulus clavotibialis (Pickard-Cambridge 1905) including five males and one female that exhibited traumatic leg injuries (missing segments). The males had sustained damage to leg IV with the affected segments including the femur (n = 3), tibia (n = 1), and metatarsus (n = 1). The injured female had injured femur II. Comparisons of walking speeds measured on an improvised trackway revealed that males with damage to leg IV did not walk significantly slower than uninjured males, females or nymphs. We used scanning electron microscopy to investigate the microanatomy of damaged leg segments and to assess their state of healing. Of the six individuals with leg damage, the freshest (most recent) injury was to tibia IV of a male and was caused by the mandibles of an ant. This wound featured a jagged border and a scab covered by abundant bacteria. Older injuries featured scarring, a rounding of the stump, and abnormal setal growth. In the case of the metatarsal injury, the healed segment superficially resembled the distal tip of an uninjured tarsus. Although this segment lacked a tarsal process, the distal surface of the healed metatarsus featured two secondary claws as well as a dense patch of ventral setae. Wound healing in harvestmen appears to follow a pattern similar to that reported for wolf spiders. However, further research is needed to assess the duration of each stage of wound repair in these arachnids as well as the overall impact of leg damage upon an individual’s survival and reproductive success.