Issue 29 December 2002 ( PDF )

Platypus poison

by Vivienne Baillie Gerritsen

Platypuses (Ornithorhynchus anatinus) are the only mammals that squirt venom. They do this from a mobile calcaneus spur situated on the inside of each hind limb. It is a sophisticated system. The spur itself is attached at its base to a small bone which can articulate; when needed it moves at a right angle to the limb ready to fire. Strangely, only male platypuses have spurs; female platypuses lose theirs during development. Platypus venom has been under close scrutiny since 1895 when two naturalists Charles J. Martin and Frank Tidswell made their first account. We know today that platypus venom is a cocktail of toxins, most of which is a mixture of proteins which resemble no other to date. These have been named the defensin-like proteins, or DLPs, because their three dimensional structure resembles that of an antimicrobial peptide known as beta-defensin.

Venom is not the only feature which makes the platypus a unique mammal. Amongst the most noticeable are its duckbill and unique orifice for both excretion and reproduction – a reptilian trait. The first specimen of a platypus was sent to England in 1798. No one could make…bill or tail of it. Chinese taxidermists had been tricking European navigators for ages with mermaid figures which were in fact the trunks of monkeys stuck to the ends of fish. So when the first platypus arrived in England, the naturalist George Shaw described it as a possible fraud.

Another peculiar characteristic of platypuses is their ability to lay eggs. Such a skill – or indeed lack of skill – lay at the heart of heated discussions amongst illustrious 19th century scientists such as Johann Friedrich Meckel, Richard Owen, Jean-Baptiste Lamark and Etienne Geoffroy Saint-Hilaire. To calm the storm, they sent a young naturalist, W.H. Caldwell, to Australia to find a few. With the help of 150 aborigines and vicious colonial behaviour, Caldwell did end up discovering some though it was not an easy task since platypus eggs are usually only laid in pairs and are no longer than 2cm.

[ Ornithorhynchus anatinus (1863), John Gould ]

Ornithorhynchus anatinus (1863), John Gould

When a platypus feels inconvenienced, it digs its spur into its victim and releases its venom. Since it is only the male platypus that has the use of such artillery, it is thought that the spurs are probably used as an offensive weapon to assert dominance during the mating season and to lay down territorial boundaries. Venom production does indeed increase during the mating season, which sustains the theory. The venom has probably a defensive role too though the aim seems less to kill than to induce intensive pain. Human poisoning is not rare and results in excruciating pain accompanied by massive swelling. Snake venom and platypus venom do seem to cause the same physiological discomforts though snake venom is far more virulent. However, it has been shown that platypus venom can kill dogs when injected intravenously.

Four major toxins make up the protein components of platypus venom, three of which are unique to platypuses: the defensin-like proteins (DLPs). Named after a class of antimicrobial peptides – the mammalian beta defensins – DLP only seems to share a comparable three dimensional structure. They are small, compact, globular proteins packed with beta-bulges, hairpin loops and beta-sheets. The fine detail of the three dimensional structure is very different though, hinting that the two types of protein do not share the same biological activity. Indeed, neither an antimicrobial nor a myotoxic activity has been detected to date. However, these compact molecules do present a structural core which could support different functional groups and hence exhibit different pharmacological and physiological activities. One possible role of DLP may be to produce – in unison with other venom components – the pain so characteristic of platypus poisoning.

Platypus toxins must participate in the activation of pain receptors, be it indirectly or directly. That is why they – like all toxins – are of particular interest in the understanding of pain-inducing effects. Ultimately a finer knowledge of what pain actually is, and by what it is caused, can lead to the development of drugs such as painkillers, which could be used to inhibit chronic pain states. Some animal synthetic analogues of animal toxins have already entered clinical trials for the treatment of neuropathologies for instance. The interest in platypus venom is that the pain is long lasting and particularly intense. And if DLPs do have a role in triggering off pain, it could lead to the discovery of novel pharmacological targets where common analgesics are ineffective.

1. Torres A.M., de Plater G.M., Doverskog M., Birinyi-Strachan L.C., Nicholson G.M., Gallagher C.H., Kuchel P.W.
Defensin-like peptide-2 from platypus venom: member of a class of peptides with a distinct structural fold.
Biochem. J. 348:649-656(2000).
PMID: 10839998

2. de Plater G.
The venom of the platypus (Ornithorhynchus anatinus)

3. Stephen Jay Gould
'Bully for Brontosaurus: Reflections in Natural History'
W.W. Norton & Company, New York, 1991, chaps. 18 & 19.
Swiss-Prot cross references
Defensin-like peptide 1, Ornithorhynchus anatinus (Duckbill platypus): P82172
Defensin-like peptide 2, Ornithorhynchus anatinus (Duckbill platypus): P82140
Defensin-like peptide 3, Ornithorhynchus anatinus (Duckbill platypus): P82141
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Does Platapus poison have any connection with tropical sprue.......

Posted by Ameilia on Wednesday 24 November 2004 20:57 CET

I am in need of information about platypus poison's uses in pain relief. I read the Spotlight article on defensin peptides, and maybe they can help. I have a friend who has RSD, and has progressed to using a morphine pump, and must use a wheelchair. If you have any information which could help I would appreciate it. Thank you.

Posted by Dolores Fleis on Tuesday 4 April 2006 11:15 CET

As it was one of my distant relatives who initialised early research into what must be the strangest animal on planet earth can I please ask this question for general comment."Does the existence of the platapus with it's duck like bill, it,s mammal tendencies and contrasting reptilian attributes make it a walking/swimming advertisement for creationism OR evolution?"

Posted by Paul Tidswell on Wednesday 5 April 2006 8:13 CET

To answer Paul's question, I would think the case of the platypus would be more proof leaning towards the side of those supporting evolutionism. I doubt god would create a freak creature with seemingly no usefulness. On the other hand, I could be wrong.

To answer Dolores's question, I do not believe enough research has been done on any pain inducing substances let alone pain relieving substances that any research scientist could begin to even make headway with this unique venom.

I believe there is hope in pain relief for those out there and for those reading this article who have relatives and are looking for alternatives to narcotics. The hope may come in venom's and poisonous substances such as the platypus venom and various other venom's, or it may come from herbs.

To those of you in pain reading this, I suggest reading up on the plant Mitragyna speciosa (Kratom). It is a rare herb that contains a slue of chemicals which are not related to the opiate (narcotic) family yet induce pain relieving effects. The main chemical that induces the pain relieving effect is 7-hydroxymitragynine or 7-OHM. Its rare, expensive and very, VERY understudied but it works (as I have personally experienced it).

it is about 17 times more potent than morphine by weight if that helps any. Although it does have tolerance potential, the fact that it is not related to the opiate family is interesting and may lead to cheaper, easier to acquire pain medicine.

Posted by Cameron Peter (my-excuse) on Tuesday 22 August 2006 20:50 CET

This is fascinating!

Are the platypus venoms similar to those of the mouse shrew? If not, has anyone worked out _when _this might have arisen in its evolution?

Posted by Gordon Cooper on Saturday 17 February 2007 8:14 CET

is there an effective pain reliever to stop the effects of platypus poison?.....if so,what would be the chances it would work for someone suffering from shingles?

Posted by william kirchner on Thursday 17 September 2009 0:37 CET

Hi! I was wondering how long the original pain and swelling lasts, if left untended and untreated. In fact, is there any treatment?
King Regards, Nicola

Posted by Nicola Rammers on Thursday 25 November 2010 4:11 CET

Would it be possible to syhthesise and refine playpus venom, and if so, how would this be done?

I ask as research for a novel I am writing...

Posted by Jay on Monday 28 February 2011 13:40 CET

i find this VERY interesting, personally.

Posted by prilla on Friday 17 June 2011 15:26 CET

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