Morphological Evidence for a Directional Flow Mechanoreceptor in Olive-Headed Sea Snakes (Hydrophis major)

Area of Science:

• Marine Biology
• Sensory Ecology
• Herpetology

Background:

• Mechanoreception in snakes, particularly sea snakes, is understudied.
• Quantifying small, numerous scale mechanoreceptors on snake heads presents significant challenges.

Purpose of the Study:

• To comprehensively quantify the morphology and distribution of scale mechanoreceptors in the olive-headed sea snake (Hydrophis major) for the first time.
• To investigate potential functional differences of identified mechanoreceptors based on their morphology and distribution.

Main Methods:

• Utilized gel-based 3D profilometry (GelSight scanner) combined with histology and scanning electron microscopy.
• Analyzed scale mechanoreceptor morphology and distribution on the head of Hydrophis major.

Main Results:

• Identified two types of mechanoreceptors: radially symmetrical smooth domes and rarer, asymmetrical peak-shaped receptors.
• Smooth domes are abundant on the snout and labial scales, decreasing in density posteriorly.
• Asymmetrical peaks, located dorsolaterally, are larger, rarer, and possess a spatially offset dermal papilla.

Conclusions:

• Smooth domes likely function in direct touch for prey handling, avoiding venomous catfish spines.
• Asymmetrical peaks may detect water flow, aiding in sensing prey escape responses or enhancing self-motion perception.
• Further physiological studies are required to confirm the proposed functional roles of these mechanoreceptors.