Venomous globiferous pedicellariae of eastern Australian Tripneustes sea urchins contain a rich diversity of cathepsin, lectin, and phospholipase A2 family proteins

Sea urchins (Echinoidea) are a class of echinoderms that are known to harbour diverse defensive traits, including long spines and pincer-like appendages called pedicellariae. Pedicellariae of the venomous globiferous type are particularly well developed in the Family Toxopneustidae. However, there is a significant lack of data on the identity of pedicellarial toxins, which is needed to characterise their function, generate insights into venom evolution and explore bioprospecting potential. In this study, we performed a transcriptomic assessment of the pedicellariae from the two toxopneustid Tripneustes species that occur in eastern Australia, both of which are suspected to possess a pedicellarial venom gland system. The pedicellariae were found to express a rich diversity of gene transcripts encoding proteins that match to known putative venom-associated proteins, particularly those of cathepsin, lectin, and phospholipase A₂ families. This study provides a foundational basis to advance discovery of sea urchin venom toxin candidates, filling a void in a field of research that has been neglected.