Thirdly, the scientists believe that as predation ramped up, the hunters themselves were increasingly vulnerable to their own enemies, such as crabs and fish. Pursuing small, easy prey might have lessened the threats posed by these other predators.
Humans are part of the equation now, but the researchers are not yet certain what affect we are having on the escalation hypothesis.
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“Marine predators, especially big ones, have been particularly vulnerable to human exploitation, including many large predatory fish and multiple groups of crustaceans, however, how these threats impact drilling predators such as moon snails is more difficult to evaluate,” co-author Michal Kowalewski of the Florida Museum of Natural History said. “In fact, it is possible that the decline of higher level predators, some of which prey on predatory mollusks, may benefit drilling predators.”
“On the other hand,” he added, “many recent environmental changes negatively affect all benthic organisms, so the long-term impact of humans is difficult to predict.”
Co-author John Warren Huntley of the University of Missouri said that in future, he and his colleagues hope to expand their database of information gathered on drill holes to refine their estimates of long-term trends in marine predation intensity. The researchers are also analyzing parasite-host interactions dating back to the Cambrian Period.
“Initial results suggest contrasting temporal trends between parasite prevalence and predation frequency,” Huntley said.
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