As light production is efficient and the cost of web maintenance is relatively low, the energetic returns associated with continuing to glow may outweigh the costs of continuing to attract prey.Īnderson JF (1970) Metabolic rates of spiders. Thus, larvae increase their investment in light output when food is plentiful or when stressed through having to rebuild their webs.
In laboratory experiments, both elevated feeding rates and daily web removal caused an increase in bioluminescent output. These results indicate that bioluminescence itself is not energetically expensive, in accordance with our prediction that a high cost of bioluminescence would render the Arachnocampa sit-and-lure predatory strategy inefficient. The mean rate of CO 2 production ( \( \dot\)CO 2 during web maintenance when not bioluminescencing was 8.95 ± 1.78 μl h −1, a value significantly lower than that measured during trap construction by other predatory arthropods. We investigated the metabolic costs associated with bioluminescence and web maintenance in larval Arachnocampa flava. Members of the genus Arachnocampa (glowworms) use an unusual predatory strategy: larvae bioluminesce to lure positively phototropic insects into their adhesive webs. Trap-building, sit-and-wait predators such as spiders, flies and antlions tend to have low standard metabolic rates (SMRs) but potentially high metabolic costs of trap construction.
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