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Does the venom of the Sydney funnel web spider have to be injected into the bloodstream to have an effect? If the venom was swallowed (e.g. if a spider was eaten), would it still have an effect? Or wouldn't it be able to pass through the gut lining, or be broken down in the gut?

I understand that the funnel web's venom is different to most spiders', but would this answer apply to spider venom in general?

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  • $\begingroup$ Interesting question. $\endgroup$ – Chris Dec 23 '14 at 22:51
  • $\begingroup$ @Chris: Very interesting. $\endgroup$ – naught101 Dec 23 '14 at 23:07
  • $\begingroup$ For the above reason, I'd also be interested to know if ethanol would degrade spider venom... $\endgroup$ – naught101 Dec 24 '14 at 0:13
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    $\begingroup$ @naught101 Ethanol would not degrade this venom. In practice, it actually stabilizes protein by inactivating proteases (enzymes that degrade protein) $\endgroup$ – Luigi Dec 24 '14 at 0:37
  • $\begingroup$ I think this question is hard to answer as toxicity will depend to a large extent on the amount of toxin ingested. Even peptide-toxins normally degraded in the gastrointestinal system may eventually become toxic when enough is ingested. $\endgroup$ – AliceD Dec 24 '14 at 3:13
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The Sydney Funnel Web Spider's venom is called δ-atracotoxin and it is especially toxic to primates. It is a peptide toxin, which means that it has the potential to be digested in the stomach before having any physiological affect. However, many peptide toxins are not inactivated by swallowing--you don't want to be eating any Botulinum toxin.

Characterization of insecticidal peptides from venom Australian funnel-Web spiders (Vonorax et al. 2006) harvested venom from Hadronyche infensa, the Darling Downs funnel-web spider. This spider is closely related to the Sydney Funnel Web spider and also produces δ-atracotoxin.

An oral ingestion activity test was undertaken using crude H. infensa venom.

The ingestion test was performed with insect larvae, which are susceptible to the venom when injected. (Aside: there's a lot of interesting research on the toxin's effect in insects). They didn't find much:

Oral ingestion activity test of crude H. infensa venom

No effect was observed in this test, even though approximately 4 times the dose required for lethality by injection was orally consumed by the larvae.

I don't think anyone has performed a study of toxin ingestion in primates (if they have, I couldn't find it). The researchers don't speculate as to why the toxin has no effect when ingested. As expected, the toxin had no effect on (non-primate) mice:

Effect of atracotoxin-Hv1 on newborn mice

All mice in both test and control groups survived without apparent toxic effect beyond 24h post injection.

Whether this is applicable to other spider venom depends on the nature of the venom. A non-peptide, low molecular weight venom able to be absorbed by the lining of the esophagus could be very toxic by ingestion.


Further reading:

Scanning Mutagenesis of ω-Atracotoxin-Hv1a Reveals a Spatially Restricted Epitope That Confers Selective Activity against Insect Calcium Channels (Tedford et al. 2004)

Isolation and pharmacological characterisation of δ-atracotoxin-Hv1b, a vertebrate-selective sodium channel toxin (Szeto et al. 2000)

(for more info on peptide toxins): Cyanobacterial Peptide Toxins

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