Beyond Venom and Constriction: Bite Performance and Trophic Ecology in the Genus Drymarchon

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  Beyond Venom and Constriction: Bite Performance and Trophic Ecology in the Genus Drymarchon Abstract Snakes exhibit extreme cranial kinesis that facilitates ingestion of prey with large cross-sectional area, but this ability is widely predicted to reduce bite performance due to decreased structural rigidity. Consequently, most large-bodied snakes rely on envenomation or constriction to subdue prey prior to ingestion. Species within the genus Drymarchon represent a notable exception: these large, non-venomous, non-constricting snakes routinely consume a wide range of prey, including large and potentially dangerous vertebrates, using only simple seizing and pinioning behaviors. Here, we quantify bite performance in three species of Drymarchon ( D. corais, D. couperi, and D. melanurus ), examine morphological predictors of biting performance, compare biting pressure to constriction pressure in similarly sized snakes, and synthesize dietary records across the genus. Our results sh...

Senecioylcholine in Heterometrus spinifer scorpion venom activates vertebrate nicotinic acetylcholine receptors

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Senecioylcholine in Heterometrus spinifer scorpion venom activates vertebrate nicotinic acetylcholine receptors

Abstract


Introduction:

Scorpion venoms are natural sources of neurotoxins that primarily modulate the properties of neuronal ion channels, particularly voltage-gated sodium and potassium channels. However, they also contain a variety of small bioactive molecules that have been largely neglected in the omics era of toxinological research.


Methods:

In the present study, we employed a high-throughput FLIPR screen of arthropod venoms against nicotinic acetylcholine receptors (nAChRs) expressed in the human SH-SY5Y neuroblastoma cell line.


Results:

The venom of the Malaysian forest scorpion Heterometrus spinifer (family: Scorpionidae) proved to be an agonist of nAChRs, and the small choline ester senecioylcholine was identified as being responsible for the observed effect. Synthetic senecioylcholine and its isomers tigloylcholine and angeloylcholine were not insecticidal when injected into sheep blowflies.


Discussion:

Based on previous reports of senecioylcholine being toxic to vertebrates along with the agonistic effect we observed on human nAChRs, we postulate that senecioylcholine in scorpion venom is likely to assist with vertebrate prey capture and defense against vertebrate predators. Since senecioylcholine has only been previously reported in marine gastropods and moths, its presence in scorpion venom seems to represent an unusual case of convergent evolution.


Prahl, R. E., Neupane, P., Salim, A. A., Lewis, R. J., Vetter, I., Capon, R. J., King, G. F., & Herzig, V. (2026). Senecioylcholine in Heterometrus spinifer scorpion venom activates vertebrate nicotinic acetylcholine receptors. Frontiers in Arachnid Science, 5, 1888189. https://doi.org/10.3389/frchs.2026.1888189