However, the researchers do note some differences between some of the toxins’ structures. The venom of these species may contain similar toxins because there are limited numbers of non-venomous proteins in nature that have the right structure to become venoms. The fact that snakes and platypuses produce many of the same types of venom suggests a remarkable example of convergent evolution, where the same traits develop independently in different evolutionary lineages. In contrast, snakes use their venom to kill prey and help with digestion year-round. Platypus venom is only produced in adult males, who use it to defend their territory from other males, and it is only produced during the breeding season. In some cases, pain at the site of injury can last up to several weeks.ĭespite the similarities between toxins in platypus venom and reptilian venom, the functions are strikingly different. Other reported effects on the body include nausea, cold sweats, gastric pain and lymph-node swelling. While not lethal in humans, the venom can cause immediate and severe pain that cannot be treated by strong painkillers. Of all the platypus’ obscure features, perhaps the most fascinating- and the one that hints at a relation to reptiles- is its ability to produce venom.Īlthough envenomation-by-platypus is relatively rare in humans, there have been a few isolated incidents. Recent research, however, has highlighted the evolutionary relationship between the platypus and reptiles. It’s part of an order of egg-laying mammals known as the Monotremes, the earliest group to branch away from the main mammalian lineage, a little over 166 million years ago. With its duck-like bill, beaver-like tail and otter-like body, it looks more like a jigsaw of several species.
The platypus has long held the title of being one of the strangest looking animals that nature has to offer. The identity of the venom component(s) that is responsible for the responses we have described is yet to be determined but is probably not the C-type natriuretic peptide or the defensin-like peptides that are present in the venom.The platypus, a mammalian oddity, produces venom toxins characteristic of reptiles in a surprising case of convergent evolution Thus the response appears to be dependent on calcium release from intracellular stores. The response to the venom was blocked by the membrane-permeant Ca(2+)-ATPase inhibitor, thapsigargin, and by the tyrosine- and serine-kinase inhibitor, k252a. Ion substitution experiments indicate that the current is a nonspecific cationic current. The venom activated a current with a linear current-voltage relationship between -100 and -25 mV and with a reversal potential of -11 mV. Application of the venom to small to medium diameter dorsal root ganglion cells for 10 s resulted in an inward current lasting several minutes when the venom was diluted in buffer at pH 6.1 but not at pH 7.4. Now we demonstrate that platypus venom has a potent action on putative nociceptors. We have previously shown that the venom contains a C-type natriuretic peptide that causes mast cell degranulation, and this probably contributes to the development of the painful response. However, platypus envenomation results in an immediate excruciating pain that develops into a very long-lasting hyperalgesia. Although envenomation of humans by many vertebrate and invertebrate species results in pain, this is often not the principal symptom of envenomation. The platypus (Ornithorhynchus anatinus), a uniquely Australian species, is one of the few living venomous mammals.
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