Limpets exhibit an extraordinary clamping force between the pedal foot and adjoining substrate to prevent dislodgement during predatory attack and high energy breaking waves. Maintaining clamping tenacity when challenged by such external forces is essential for survival on intertidal rocky shorelines. Localised fuel spills present a risk to limpets and similar intertidal species reliant on tenacity. In this study Cellana tramoserica showed a 50% dose-response decrease in tenacity following 24 hour exposure to the water accumulated fraction of diesel (EC50 14.8% diesel WAF) in seawater. The pedal sole of the foot displayed histological evidence of ecdysis of the epithelial cell layer following 40% diesel WAF exposure. However, absence of a dose-response in histological alteration to muscle fibres and side-wall of the pedal foot indicates a rapid onset of a necrotic response inhibiting muscle contraction resulting in loss of foot rigidity essential for maintaining tenacity, more so than a morphological alteration inhibiting foot rigidity and adhesion. Understanding the likely tenacity response of limpets to diesel offers a rapid, quantifiable in situ biomarker of effect on limpet health following coastal fuel spills.