Connected Microscopy to Characterise the Dermal Denticle of Raja clavata, the Thornback Ray

Thornback ray, Raja clavata, have multiple dermal denticles positioned on the dorsal side of their bodies. These dermal denticles are formed through the deposition of minerals by the epidermal and dermal cells, and their structural makeup is a dentine protrusion with vitrodentine on the outside (1,2). The possible function of dermal denticles across different species has led to debate, ranging from protection of predators and mechanical abrasion, to enhanced swimming performance, or deterring attachment of ectoparasites (3). The dermal denticles found on skates are larger, therefore the widely accepted function is defence (3). Biological materials and biomineralisation is dependent on the environment, utilising moisture, temperature fluctuations, loading, and chemistry to create complex chemical and biological structural relationships with often enhanced structural integrity (4). Analysing and understanding the complex ways the microstructure is arranged to achieve stiffness, strength and toughness can be used for bioinspiration (5).