Why Do Venomous Animals Live In Warm Climates?

As a Canadian-Australian, I have always wondered why it is that Australia has so many venomous animals that can kill you while Canada has virtually none.

But it's not just Australia - it seems like all beautiful, warm places are cursed with venomous native species. So I set out to find the truth: why have all these venomous species evolved in the world's best holiday destinations?

I asked chemists, visited the zoo, interviewed entomologists and snake experts. The answer I found was complicated:
1. The majority of venomous species are ectotherms, cold-blooded creatures whose internal temperatures are governed by their surroundings.
2. This means they have limited periods of activity - mainly while it's warm out, and can only exert short bursts of energy, so they are generally "sit and wait" predators. This may explain why they, more than mammals or birds, evolved venom.
3. It also explains why there are more of these species in warm climates. There are more of all species in warm climates, but this trend is especially pronounced for ectotherms.
4. So there are a greater number of venomous species in warm places, simply because there are more species in warm places. Cold climates still have venomous creatures, like the rattlesnakes of Canada and European vipers.
5. But history also has a role to play. In Australia, there were no snakes until 20 million years ago when a venomous sea snake from Asia encountered the land, sending venomous species to all corners of the continent. Later non-venomous arrivals have done well in the tropics but not as well in Australia's colder climates, so venomous types still dominate there. Hawaii has no venomous land snakes and nor does Jamaica.
6. The recent ice age also would have driven ectotherms from the northern parts of the Northern Hemisphere. This is why there are no snakes in Ireland, for example.

Special thanks to Prof. Rick Shine, Prof. Dieter Hochuli, Prof. Roger Lowe, Prof. Martyn Poliakoff and Taronga Zoo, especially Joe Haddock and Dean Purcell.

Cinematography by Charles Clement

[kilgoretrout]

I've spent years trying to unpack a totally irrational fear of spiders. Somehow, hearing the phrase "all spiders live on soup" has undone all of that work in mere seconds.

[hawkanhawks]

11 years old and I barely noticed. Insane consistent high quality!

[ALBINOD]

"I found this Reddit thread on the topic, though it really didn't explain why that was the case"

He must never have been on Reddit before.

[zappin]

I like to imagine that Australian professor does in fact enjoy venom with his scotch, and that’s how he knows.

[Ometochtli]

I'm up in Canada and always wondered this. We do have some venomous spiders up here. But their venom is generally only toxic to other insects. We don't really have any venomous creatures that can produce a venom strong enough to pose a threat to humans. It seems like colder climates not only get fewer venomous creatures. But the venom also gets less deadly. Maybe it has to do with the fact that most venomous creatures are cold blooded, and there are extremely few venomous mammals.

Australia : Watch out! That spider's venom is deadly enough to kill 10 men with a single bite.

Canada : Watch out! That spider's venom will give you a mild rash for about a day.

[scavi]

1:40 ah, the good old times, when Sudan had no south and Germany had a wall

[CrimsonHelldrake]

2:15 *the most stereotypical, cliche fitting of the role looking professor I have EVER seen*

[paco_rms]

"The country with the most venomous species is Mexico"

Me, a mexican: ... Wait, WHAT?

[ameliabrittain]

I noticed you say “Australia” in an Australian accent! It also sounds like you are fighting yourself not to lean into the Aussie accent on certain words even tho it’s clear you want to, which as a southern from a big city, happens to me EVERY TIME I talk to my rural grandparents. I don’t have much of an accent, but when I talk to them I go into a full drawl. It’s crazy how much the people we talk to affect our own speech.

[arsaeterna]

I LOVE how you speak to my inner child
the questions I had as a kid
so important to understand how the world really works

[karlhiscock]

"Ireland has no snaked because of an Ice age"
St. Patrick is typing...

[TheBoomamatic]

3:17
closethelid
CLOSETHELID
CLOSE THE LID
CLOSE THE LID
CLOSE THE LID
CLOSE THE LID
CLOSE THE LID
FOR THE LOVE OF GOD CLOSE THE LID

[arsaeterna]

St Patrick banishes the snakes from Ireland

Veritasium Derek: ICE SHEET

[aaronrdaniels]

Favorite part about this channel is the quality was so good 8 YEARS AGO! The mic quality is the only noticeable real change over the years.

I can continue to re-visit videos to learn the same thing I learned years ago :)

[SevyDevi]

Thank you so much for clarifying the difference between "venomous" and "poisonous".

[zolfirthedragon]

the UK has a grand total of 1 venomous reptile. We love you, Adder

[GS-tdyc]

He: "Modern Snakes are losing venom, which is important for their survival."
Me: "Because snakes know human kills venomous snakes."

[keep_walking_on_grass]

3:02 my gosh, I would not feel safe while he is talking to me..holding that vessel in his hand...

[helicrashproprocrasher]

Just wanted to throw this out there. I had a clutch of copperheads born in captivity unexpectedly. Copperheads like most vipers do not lay eggs but have "live birth" (Ovoviviparity). Before the 14 babies where able to be separated, about 1/3 where dead due to bites from their litter mates. They where very nippy at anything that moved and being in such close proximity to one another, they where nipping each other and envenomating each other. One might think that a snake is immune to its own venom but that is not the case. This might be the reason snakes have evolved away from having venom, it can also be dangerous to the animal carrying the venom. Brings a whole new meaning to biting your lip. While other snakes like King Snakes have evolved immunities to venomous snakes so they can prey on them, yet are not venomous themselves.

[BeastGuardian]

I love that this video does such a nice job of illustrating that correlation does not necessarily imply causation.