By Christopher Kemp
In the 2004 Discovery Channel docu- mentary “Killer Jellyfish,” Australian toxinologist Jamie Seymour is stung by an Irukandji jellyfish. A box jellyfish, the Irukandji is pea-sized and transparent. It drifts through the water like a ghostly
mushroom. For hours after he is stung, Seymour writhes on a hospital bed, his chest
covered with EKG leads. His legs tremble.
His agony lasts for 50 hours. In others it
lasts longer—2 weeks or more. And, sometimes, it’s fatal.
An evolutionary biologist at the University of Hawaii, Christie Wilcox studies the
evolution of toxins in lionfish, scorpionfish, and species like the Irukandji jellyfish.
With Venomous, she takes us on a biochemical tour of the natural world, examining
how certain species have evolved the ability
to defend and kill with venom.
The honey bee uses a toxin called melit-
tin. Both the blue-ringed octopus and the
pufferfish use tetrodotoxin—a potent neu-
rotoxin that inhibits the firing of action
potentials in nerves. The male duck-billed
platypus unleashes venom from 1-inch-
long toxic spurs on its ankles; its produc-
tion requires 83 different genes. Covered
in bristles, the Lonomia caterpillar delivers
a substance that begins with hemorrhagic
shock and ends with organ failure. Vipers
use hemotoxins: the body bleeds to death
inside. The cone snail—Conus geographus—
doesn’t sting many people, but it kills 70%
of those it does. Generally, bites are offen-
sive and stings are defensive.
Despite all of our best efforts, writes Wilcox, the effects of bites and stings are still a
problem worldwide. In India alone, the four
most venomous snake species—the Russell’s viper, the saw-scaled viper, the spectacled cobra, and the common krait—still
manage to kill tens of thousands of people
every year. Usually, they kill poor people in
remote places. The antivenom exists, but it
Interestingly, the diversity of venomous
strategies across species is not as great as
one might at first think. Some very different
species have evolved identical toxins, acting
on the same internal systems and cellular
pathways. Snakes, jellyfish, and spiders all
produce tissue-destroying phospholipase
A2. Snails, corals, and worms all produce
Kunitz-type peptides, which prevent other
proteins from functioning properly. Some
species, particularly the cone snails, recruit
a cocktail of hundreds of venomous com-
pounds, but, even then, many of them are
the usual suspects.
From an evolutionary point of view, if an
idea is good enough, more than one species
will have it, and some species will have the
same idea again and again. Reptiles have
recruited phospholipase A2 at least four dif-
ferent times in their evolutionary history.
As Wilcox explains all this, she travels to
Tasmania to observe a duck-billed platypus;
treks into the Peruvian jungle to find the
dreaded Lonomia caterpillar; and flies to re-
mote Indonesian islands to observe the Ko-
modo dragon, whose venom acts as a potent
anticoagulant and causes a rapid decrease in
blood pressure that induces shock. We meet
toxinologists who study venoms and also
self-immunizers—a small group of laypeople
who willingly inject themselves with diluted
snake venom, reporting that cobra venom
gives them a high that is better than cocaine.
The subject matter Wilcox is writing
about sits at a fascinating intersection be-
tween the human and the natural worlds.
We are interested in these deadly ani-
mals—the jellyfish in the water; the cam-
ouflaged scorpion beneath the rock, poised
to strike—precisely because of what they
might do to us. The idea of being bitten
by a rattlesnake in the desert, miles from
anywhere, fills us with dread.
Wilcox tells us that thousands of people
are bitten and stung each year. So, where,
I wondered, are the testimonies of the
snakebitten? Where is the desperate and
dry-throated rush across state lines for a
vial of antivenom as the bitten hand turns
into a shiny red balloon? For a subject with
such a human impact, I was constantly
wondering: Where are all the people?
Our understanding of the biochemistry
of venoms, and how they evolved, is still incomplete. The field of venomics, the study
of naturally occurring venoms as a novel
drug discovery platform, is in its infancy,
too. Wilcox does a good enough job of introducing us to them both. But the dread—
the leg-trembling agonies Jamie Seymour
endured after his Irukandji sting—must be
looked for elsewhere.
An insider’s guide to venomous creatures delivers on the
science but is short on tales of the bitten and stung
How Earth’s Deadliest
Straus, and Giroux, 2016.
The reviewer is at the Department of Translational Science
and Molecular Medicine, Michigan State University, Grand
Rapids, MI 49503, USA. Email: email@example.com
BOOKS et al.
A potent combination of anticoagulants
and vasodilators amplifies the
lethality of the Komodo dragon’s bite.