Unexpected venomous animals | Venom: The secrets of nature’s deadliest weapon

By Jesse Hawley

10 November 2017

An array of venomous creatures covered in ‘Venom’. Top left: blue-jeans frog (Daniel Solabarrieta), Top middle: blue-ringed octopus (Noodlefish), Top right: Hammerhead worm (Vengolis), Bottom left: slow loris (Dick Culbert), Bottom middle: blue dragon sea slug (Sylke Rohrlach), Bottom right: platypus (Matt Chan)

Venom: The secrets of nature’s deadliest weapon is out now from CSIRO Publishing. To celebrate, we’ve concocted a deliciously toxic blog to get into your system.

What’s the first image that strikes you when we say ‘venom’?

Thanks to evolution building personal alarm mechanisms over countless generations, it’s likely snakes. After snakes, probably spiders, bees and wasps spring to mind. But the world of venom is so much more than these animals — there are over 200,000 species of venomous creatures. A lot, huh? And they’re spread all over the animal kingdom. This blog we’re going to cover some of the less spoken about venomous animals, the sly ones. Before that, though, let’s talk about venom itself.

What is venom?

There are venoms, there are poisons, (there are toxins), and there are differences. Let’s start with venom; it’s topical. Venom is made by animals for animals. Not just that, but venom needs to be injected by striking, spearing, or penetrating flesh. This is the primary definition of venom: creating a tear in the temple that is your body with fangs, claws, stingers, harpoons, etc. to administer venom into your system — just think ‘intravenous’. Since it has to be injected, we weren’t being strictly accurate when we said ‘venom is topical’.

The blue-jeans frog or strawberry poison-dart frog; not a venomous animal, but a poisonous one, meaning any ‘strawberry kisses’ are going to land you in some hot water. Image: Daniel Solabarrieta/Flickr/CC

Beyond the fact that venom is made by animals to be injected into other animals, venom is also complicated. Venom molecules are often highly specialised cocktails of toxins (by the way, toxins are anything toxic: poisons, venoms, late night TV). When we say ‘complicated’ or ‘specialised’ we mean evolution has been tinkering at the molecular structure for some time, crafting a masterful skeleton key to unlock and disrupt your body’s functioning.

In a lot of cases, venom had harmless origins and was co-opted, hired for a different job than it had before. Consider our cells, which are held together by a jelly network of collagen and other gloopy proteins. Naturally this jelly network called connective tissue needs to be broken down to heal wounds and even for growth — from a foetus to the lovely specimen reading this article. We and other animals have special enzymes that do this job. But what has the king cobra done? It’s only gone and evolved a duplicate of these normally constructive enzymes and used them to inject into other animals. After the prey cops a dose of this turn-coat venom, the enzymes go about doing their job, dissolving tissue, eating through cells, creating a follow-through path at the bite-site for yet more venom to flow. Nasty.

And consider this — we humans eat starchy vegetables, breaking them down for a sugar hit. Starch is composed of building blocks called amylose that need to be broken down, digested, by complicated enzymes. It just so happens that we’ve evolved those starch-destroying enzymes in our saliva. So, when you bite into, say, a roast potato, your saliva is ‘pre-digesting’ the starch before it gets to your stomach. This makes you a type of pacifist vegetable envenomator. This is exactly what many snakes have done with their saliva, turning it into an out-of-body digester, saliva that gets into your system, bursts your cells, rots your flesh, and clogs your blood before you’ve even been eaten! It’s rough being a sentient potato.

Platypus diving

Not all venom is used for killing prey and traumatising us squeamish humans; male platypus have venomous spurs on their hindlegs which they use for sexual jousting with other males. They’re the only mammals that stab venom into their target, (excepting certain twisted humans). Some evidence suggests that male platypus may also use their spurs to injure recently copulated with females to stop them from mating with other males, a type of monotreme munchausen by proxy. Not so cute now. And talk about a toxic relationship. Image: Matt Chan/Flickr/CC [featured]

In order to perform these impressive functions, like turning your blood into jelly, kick-starting cardiac arrest, and other more stand-up effects (we’re looking at you, Brazilian wandering spider), venom must be necessarily sophisticated or intricate to mimic and disrupt the body’s natural rhythm. This makes venom ‘delicate’ in structural terms. And since it’s so delicate, it’s easy to destroy. This is one reason why venom has to be injected into your blood to function, a marked difference from poisons. If venom were swallowed, your stomach acid would destroy the delicate molecules and leave you with nothing more than placebo-induced paranoia for a few hours. That is, of course, unless you have cuts along your digestive tract…

That’s it for our introduction on venom itself, let’s talk about some venomous creatures.

Blue-ringed octopus

The curiously named blue-ringed octopus. Image: Noodlefish/Flickr/CC

Like checking twice before crossing the road, running with scissors, and bees in opened soft drink cans, blue-ringed octopuses are in our collective consciousness as alarm triggers, tiny cephalopods coiled in rock pools biding their time before they’ve the opportunity to end our life. And perhaps, for good reason.

Quick cool fact: Not just blue-ringed, but every species of octopus, squid, and cuttlefish is thought to be venomous — that’s all cephalopods except nautilus; they can do no wrong. (It also makes the colossal squid the most colossal venomous entity, creepy.)

Yes that’s right, blue-ringed octopuses are venomous, meaning they inject you with their concoction of venom via a peck. In case you’re late to the cephalopod party, octopuses and squids have beaks for cracking shells and such. If you’re ‘pecked’ by a blue-ringed octopus you may not feel it until your arms and legs begin constricting and seizing, your heart begins to spasm, and your breathing gets tighter and tighter until your diaphragm ceases flexing your lungs and you suffocate a mere few minutes after the bite. This goes for the other 25 people a single octopus can lay to rest. Take a deep breath, you haven’t actually been bitten.

Surprisingly the octopus’s neurotoxin, known as TTX (it’s even a scary-looking acronym), isn’t actually made by the octopus, but by bacteria it carries in its salivary glands. These bacteria hang out in these salivary glands, apparently happy with their accommodation, and in terms of rent, they pay up with an extremely potent neurotoxin that the octopus uses to catch food for housekeeping. Well done, team.

Newts

Rough-skinned newt on a sawn off stump

Black on top, red on bottom says ‘I highly recommend keeping your hands to yourself’, but we’ll get to that later. Image: DSHil/Wikimedia Commons

Like frogs, newts are amphibians; and like many frogs, many newts are poisonous — that is, touching the skin of these animals and getting the poison on your ‘mucous membranes’ (your eyes, nostrils, lips) will get you awfully sick. If you think that’s a sloppy defence mechanism, when was the last time you cooked with chilies?

Newts produce toxins from glands on their skin (think about cane toads), which act as protection from being touched, especially by a mouth. One species of newt, the rough-skinned newt, produces TTX, the same toxin present in blue-ringed octopuses and many other marine creatures. Interestingly, though, TTX isn’t produced by bacteria, but by the newt itself. A self-made newt. Why in the world does this unassuming amphibian need toxins of this nuclear magnitude? Well, because its predator, the garter snake, is largely immune to it. And, going back in evolutionary time, when the rough-skinned newt had a more mild poison like its cousins, the garter snake slowly became immune to that, too, necessitating a tougher defence. And, as they say in biology, this kicked off an evolutionary arms race resulting in a modern day newt with the power to slay the queue of a newly opened frozen yoghurt parlour.

The side of P. waltl. Image: Václav Gvoždík/Wikimedia Commons

You might be thinking, ‘Hey, this is an article about venomous animals and this newt is poisonous, not venomous as per your aforementioned definitions’. Well observed, discerning and verbose reader. Let us introduce you to the Iberian ribbed newt, Pleurodeles waltl. This newt, we’ll call P. waltl has ribs tipped with pricks. And along the outside of its body, the skin, like other newts, is pocketed with poisonous glands. When a predator like a heron chomps down on P. waltl, the pressure pushes the pricked ribs through the newt’s body wall and skin, through the poison glands, and into the mouth of the horrified heron. It’s like biting into a bone shard in a chicken sandwich, except it’s laced with lethal toxins. This, by definition, makes P. waltl venomous. And don’t worry, just like Wolverine they’ve got regenerative properties and a great immune system so they’re back to eating worms in no time.

Sea slugs (the blue dragon)

The blue dragon, Glaucus atlanticus, swimming upside-down because why not. Image: Sylke Rohrlach/Flickr/CC [featured]

Like in Walking Dead when domesticated humans have their homes stripped away, casting them into the wilds where everything’s out to eat them, and in order to survive they have to steal weapons and become rather colourful characters, the blue dragon is a snail without its shell, a being without refuge.

With no shell to cover their vulnerable squishy body, the blue dragon has evolved a very unique venomous defence from the food that it eats. The blue dragon feeds on blue bottles, a.k.a. the Portuguese man o’ war — a venomous animal unto their own. If you’ve ever been to the beach and become entangled in the blue tentacles of doom from a blue bottle, you’ll know how effective these stingers are. One minute you’re flailing happily amongst the waves, the next, you’re running up the beach having strangers recommend you slather yourself in sand and urine, as if things aren’t distressing enough.

The stingers are absolutely tiny and are called ‘cnidocytes’. They’re the defining feature of a large group of animals including all corals, anemones, jellyfish, and…blue bottles.

A colourful diagram for how cnidocytes (containing cnidocysts) work. Image: Spaully/Wikimedia Commons

Cnidocytes are a particularly neat, almost industrial type of venom injector. They line the tentacles of blue bottles like harpoons on the bow of a ship. Here’s a description from Venom the book: ‘Nematocysts are essentially high-pressure, venom-filled capsules that contain a harpoon-like stylet, and a tightly coiled, inverted syringe-like filament. Upon triggering, the stylet shoots out in the fastest known motion in the animal kingdom, accelerating from 0–100 km/h in just 700 nanoseconds, with a piercing power similar to that of a bullet. Following penetration by the stylet, the filament is turned inside out in a twisting, drilling motion, reaching deep into the tissue of its victim where the toxic content of the nematocyst is released to cause paralysis and tissue destruction…it’s the oldest known venom delivery apparatus in the animal kingdom.’

Well the blue dragon sea slug eats those. And see those wonderful projections like kaleidoscopic blue flames at its side? That’s where it excretes the venomous cnidocytes, to those frills, making them more dangerous than the blue bottles they stole them from. If you can’t make weapons, eat those who can and assimilate their technology.

Flatworms

A hammerhead worm. In terms of threat level, a definite one-up from the shark. Image: Vengolis/Wikimedia Commons

Don’t worry, this isn’t a prop from Ridley Scott’s latest attempt at destroying the Alien franchise, this is a hammerhead flatworm. Free-roaming flatworms like this one are relatively harmless. They’re predators and roam around feeding on other worms, because what are you going to eat if you’re a worm? (Just kidding, some worms like nemerteans can grow up to 55 m long and eat fish whole.)

In 2014, two species of hammerhead flatworms were found to contain our old friend TTX, making them the first non-backboned animals on land to contain the deadly toxin.

You’ll notice the familiar yellow and black colouration on this individual. Many poisonous or venomous animals want your attention to say ‘back up or you’ll get hurt’. It’s warning colouration, also known as ‘aposematism’ (translating to ‘sign to keep away’) and it has evolved to advertise danger. The colours are often vibrant, jarring and contrasting, taking advantage of humans’ and similar animals’ pre-existing flags of interest. Yellow on black. Red. Blue. We’re so used to seeing every other colour in nature, these ones are fresh alarms — a visual palate cleanser. Yellow on black is used by wasps, sea snakes, the radioactive symbol, and the oddly dressed Odlaw, Wally’s mate who sticks out like a sore thumb.

Pick up a copy of Venom: The secrets of nature’s deadliest weapon

In this blog, we’ve told you about a mere handful of the hundreds of thousands of venomous species out there. We didn’t even get to the venomous crustaceans, bugs, and mammals, nor our cultural and collective awe of venom and venomous creatures. There’s so much to learn — just check out these chapter titles: Chapter 4, Dissecting the Power of Venom; Chapter 5, Evolving Venoms; Chapter 6, Cultures, Cures, Quackery and Cosmetics.

Sunda slow loris. This is the only venomous primate. Now, fellow primate, don’t get jealous. The slow loris has become the victim of pet-trading due to its adorable threat display. To ward off threats, the slow loris lifts its arms, displaying its poisonous armpits, which it can lick to arm its teeth with a venomous bite. Image: Dick Culbert/Flickr/CC [featured]

Venom: The secrets of nature’s deadliest weapon

Pick up a copy, here, and let us know what you learn!