The music video for Britney Spears' hit Toxic would have been so much better with truly toxic creatures in starring roles. Can you imagine the pop star serving drinks to newts, dancing with a pufferfish, and finally, of course, succumbing to the deadly embrace of a blue-ringed octopus?
When I wrote about the toxicity of flamboyant cuttlefish a few entries back, a thoughtful commenter linked to a journal article about cephalopod toxins, and a popular news story covering the findings. The study is interesting, to be sure, but I disagreed rather strongly with some of the authors' assertions.
I didn't have time then to look at the pop-sci story, but now I have, and I find it has similar holes. It hypes "the discovery that all octopuses, cuttlefish and some squid are venomous," which is not a "discovery" that I had seen anywhere in the original paper. They published on samples from two species of octopus and one species of cuttlefish. That's it. They may have data from more animals, but they don't even mention them in the paper.
Fry says although the blue-ringed octopus (Hapalochlaena sp.) remains the only cephalopod species dangerous to humans, it does not make the deadly toxin. Instead it is produced by endosymbiotic bacteria, which live in a symbiotic relationship within the tissues of the invertebrate.
This assertion is in the paper too, and I would just love to know where the data are coming from. The postdoc in my lab who studies TTX (tetrodotoxin, a rather nasty neurotoxin found in animals as diverse as octopuses, pufferfish, and newts) tells me that no one is really sure how any of these animals produce their toxins. It's just one of those yet-to-be-figured-out scientific questions.
But this is by far best part of the news story:
Really? There are no coincidences in nature? Is that a fundamental principle of biology that I somehow missed learning?
Because "there are no coincidences in nature", Fry says the universal presence of these proteins suggests they have structural or chemical properties that make them predisposed to be useful as toxins.
It's not that I disagree with the conclusions being drawn. If you discover (as they did) that very similar proteins have been co-opted as toxins in a variety of different organisms, it does seem reasonable to look for some fundamental structural or chemical characteristics that might have facilitated such evolution.
But there could be a more scientifically rigorous way of stating it.