New research has revealed the brutal feeding behaviours of golden ghost crabs, which prey on loggerhead turtle hatchlings on Australia’s Ningaloo Coast.
The study, led by Edith Cowan University (ECU) and the Department of Biodiversity, Conservation and Attractions (DBCA), sheds light on how these crabs – which are endemic to the west coast of Australia – threaten the survival of the endangered loggerheads.
Loggerhead turtles already face numerous threats, but this study provides rare insight into one of their most gruesome challenges – predation by ghost crabs shortly after hatching, says Dr Casper Avenant, lecturer at ECU and author of a follow-up paper published in the journal Food Webs.
These hatchlings must scramble from their nests to the sea, often under the cover of darkness, where ghost crabs (Ocypode convexa) lie in wait.
Ghost crabs on the hunt
Using infrared videography, researchers were able to observe ghost crabs' behaviours in the wild. This technology allowed them to document the moment the crabs seize hatchlings by the neck with their large claw, then use their smaller claw to sever or partially sever the head before feeding.
"In two of the feeding assays, the hatchlings' heads were completely separated from their bodies within less than 2 hours," says Avenant, "after which the crabs fed from the cavity in the neck region of the body."
These scenes had previously been difficult to capture due to the nocturnal and remote nature of the events.
The study also found that ghost crabs, which are usually omnivorous and consume brown algae, showed a clear preference for animal flesh in both natural and controlled environments. In the wild, crabs anticipate the emergence of loggerhead hatchlings, "often congregating near nests in the moments prior to emergence," explains Avenant.
Professor Glenn Hyndes from ECU, adds: "On beaches where ghost crab densities are high, multiple crabs can feed on hatchlings emerging from nests over several nights, often resulting in partial destruction of turtle clutches."
Avenant’s earlier work found that up to 80% of loggerhead turtle eggs were predated within a single rookery at Ningaloo. Even among hatchlings that made it out of the nest, 45% were still targeted and eaten.
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This research not only highlights the scale of ghost crab predation but also underlines the importance of understanding predator-prey dynamics in managing and protecting endangered turtle populations, says Avenant, who suggests that the findings could help inform conservation strategies for loggerhead turtles along vulnerable coastlines.
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