About This Project

Hammerhead sharks are obligate ram-ventilator, needing constant motion to breathe. Recent studies on S. mokarran and S. lewini reveal they can reduce energy by swimming sideways, showing a rhythmic rolling behaviour. This behaviour hints at possible circadian control, suggesting microsleep cycles during the day and navigation recalibration at night. The SCUBA project aims to understand these rhythms through tracking and manipulation, offering insights for conservation strategies.

Ask the Scientists

What is the context of this research?

Hammerhead sharks, including the critically endangered species Sphyrna mokarran, S. lewini, and S. zygaena, face numerous threats such as overfishing and habitat destruction. Conservation efforts are gaining momentum, driven by global initiatives like the European Green Deal and UN Goal 14. Understanding their biology, including circadian rhythms, is crucial for effective conservation. While most organisms have evolved circadian clocks to adapt to Earth's rotation, sharks in constant environments or with unique behaviors challenge conventional understanding. Research on their rhythmicity and clocks is incomplete, raising questions about their necessity and function in these species.

What is the significance of this project?

Hammerhead sharks (HS) are semipelagic obligate ram ventilators, requiring constant motion to oxygenate their gills. Recent findings suggest they minimize energy expenditure by using their dorsal fin and swimming on their sides. Despite their perpetual activity, they exhibit rhythmic rolling swimming behavior (RSB), particularly pronounced during the dark phase. Understanding the regulation and significance of this ultradian rhythm is crucial for appreciating their ecological role and susceptibility to environmental changes, informing effective conservation strategies.

What are the goals of the project?

Under the mentorship of Prof Nicholas Payne from Trinity College Dublin , Dr Mark Royer from the Hawaiʻi Institute of Marine Biology and Prof Emilio Sperone from the University of Calabria, I aim to explore the biological basis of the rhythmic rolling swimming behavior (RSB) in the Scalloped Hammerhead Shark (Sphyrna lewini). Through an interdisciplinary approach blending chronobiology, experimental biology, telemetry, and population genetics, the research will elucidate the function of RSB, identify circadian influences, and uncover genetic markers driving phenotype plasticity.