Cone Snails, Beauty can kill or will it save us?
She sells sea shells by the sea shore.
Some of the earliest forms of art and jewellery that the human race created were from ‘pretty’ shells found on beaches and the shells of Cone snails are among some of the most abundant, in early centuries the shells of Conus Gloriamaris were incredibly sort after. Luckily the majority of species of Cone snails are not venomous or harmful in anyway, unless of course you tread on them in bare feet! But I am here to tell you that its not all fun and games, as a few of them are incredibly dangerous and can even kill a fully grown human in a couple of hours, however they are also providing hope for the future.
First things first.
Now as I said not all, in fact only a very small percentage of Cone snails are dangerous and the first thing we have to do is try and figure out which are safe to handle and which are an absolute no no. Now with all of the advancements in biology in recent years you’d think it would be save to say that it has become easier to identify and classify species… WRONG! That is not the case for cone shells, in fact there has been a huge amount of debate as to how to precisely do this. The most recent classification sees the cone snails grouped into a single family that contains four separate genera, most of the harmful cone snails being grouped into the Conus genus.
Small, but deadly.
Despite their small size the venom of the most dangerous cone snails, such as; Conus geographus, Conus tulipa, Conus striatus, actually packs a mean kick that is powerful enough to be fatal to a fully-grown human.
Like several other cone snail species the venom used is actually an incredibly varied cocktail of different compounds and changes depending on each individual species, most contain a mix of neurotoxins, peptides that target specific pain receptors and pathways and even pain-blocking compounds.
All of these conotoxins make up one of the most dangerous venoms in the world, causing localized pain, numbness, swelling and vomiting in the best case scenarios but the larger species can cause disturbances in vision, multiple paralysis and respiratory failure resulting in death. As there is no real anti-venom to such a large, varied mix of toxins in one go, the majority of treatments involve just trying to keep the victim alive until the effects have worn off.
Weapons of the enemy.
In order to get this nasty concoction of toxins into its prey the cone snails have developed an impressive weapon; a harpoon like proboscis with a small ‘barb’ or ‘hook’ on the end that is connected to the venom sac. Once in range, the proboscis is extended rapidly, effectively ‘firing’ the harpoon at its enemy and injecting the deadly venom. Normally one shot of venom is enough to subdue any prey that the snails are hunting, all the way from other snails, molluscs and worms to small fish. Once hit the target normally enters a state of paralysis within a few seconds and with no means of escape is then swallowed whole and digested alive by the hungry cone snail. With regards to human interaction however the symptoms of a sting may not start to become apparent until a few days after depending on which species it was and where the person was sting. This makes it very tricky to treat as people can suddenly and without any apparent cause start suffering from paralysis!!
It’s not all doom and gloom though!!
As bad as all of that may sound the cone snails may actually be some of the new heroes of the medical world. The very thing that makes them so dangerous, this abundance of nasty toxins, could hold the key to curing many diseases that have been incredibly difficult to make any head way in. The reason that these toxin are so useful is the fact that the compounds they are made from target specific type of receptor cell while completely ignoring all others, meaning that they can quickly and precisely cause the desired effect with very little side effects. One such drug that has been developed from some of these toxins is Ziconotide, which was approved for clinical use in the USA in 2004 and is roughly one thousand times more potent then morphine. This is all due to the venom of the Conus magus, commonly known as the magician cone snail. The peptitdes in its venom, as well as other various cone snails, are also being studied with the prospectus that one day they will help in the development of medication that could help with conditions such as Alzheimer’s disease, Parkinson’s disease, depression, and epilepsy.