Monthly Archives: March 2010


Say what you will, but jellyfish, a.k.a ‘jellies’ a.k.a. ‘true jellies’ a.k.a. ‘medusae from the phylum Cnidaria’ (trans. ‘jellyfishes’) have done quite well for themselves in spite of their obvious limitation of lacking any brains.

This is not to be confused with the colloquial expression ‘he/she has no brains’ – meaning that he/she has a physical brain present, yet said brain is a Raiders fan, or said brain is sure it found a system for winning at Keno, or said brain got kinda drunk and argued somewhat convincingly to itself that it was okay to eat a bacon-wrapped hot dog from a street vendor in Tijuana1.

Rather, jellyfish literally have no brains. At all.

‘Hey, I just had an idea. Wait…no…it’s gone.’

Yet succeed they have. Comprised of about 95% water (and 0% brain) jellyfish can be found in stable populations throughout the world’s oceans, from top to bottom and also in freshwater. And there are at least 2,000 different species.  And they accomplished all of this without the benefit of an iPad. Impressive.

Not only have they traveled the world and done fairly well despite their brainlessness, jellyfish also manage to kill and devour their prey and deter predators.  Now, one probably wouldn’t be very afraid of a shark that didn’t have a brain. Or a snake without a brain. Or a bear. Indeed, it might be entirely hilarious if a brainless bear was trying to attack you. There’d surely be a website called and it would be ‘dedicated to providing the most recent videos of brainless bears trying to do things.’ But yet we all intuitively sense that a jellyfish – even a brainless one – is a different matter altogether. And that intuition turns out to be completely correct.

One of the hallmark features of Cnidarians (and therefore jellyfish) are tiny organelles called nematocysts, which are specialized stinging apparatuses that have been described as miniature ‘cocked guns.’ Embedded in the tentacles (and requiring much less maintenance in salt water than actual cocked guns), nematocysts contain tiny, coiled, often-barbed, poisonous threads that plunge venom into the skin of anything unfortunate enough to brush up against a jellyfish. This effectively paralyzes small prey and has ruined many an impromptu skinny dipping session.

Now I remember. I was going to kill you and eat you. I knew it started with a K.’

Perhaps not so surprising for an animal lacking a brain, the jellyfish developed only one gastrovascular opening for both the mouth and the anus2. Known in the jellyfish community as ‘The Great Mistake,’ the mouth/anus serves to devour plankton, fish, crabs, barnacles and sometimes other jellyfish. And then to poop same meals back out later. Adorable.

The Great Mistake aside, jellyfish reveal one of nature’s nasty little paradoxes: Successful evolving – being the fittest and thus ‘the best’ and going on to make a decent living – does not require a brain. However you turn that over in your massive neural network, it surely must diminish the relative standing of humans in nature. And then when we consider that some people (with brains) on our planet actually consider jellyfish a delicacy (even after being informed that there’s no jelly in them), it only takes us and our giant brains down several more pegs. Which is certainly not anything we look for, but something that still has the benefit of reminding us not to spend so much time wondering 24/7 how we’re doing vis-à-vis everyone else, what it all means, what should we really be doing with our lives, is now a good time to buy a condo, et cetera.

Thanks, jellyfish.

Grade: C-

1 Or said brain works in the local coffee shop and when an Animal Reviewer ordered a ‘half decaf,’ said brain asked the Animal Reviewer what he wanted as the other half.

2 This is why the curriculums of jellyfish dentistry schools are virtually identical to those of their proctology programs. Same book and everything.


Dear readers, fans, friends, and our mothers,

The Animal Review book is soon upon us. Featuring some of your favorite posts from this blog (updated) and new reviews of many surprise animals, The Animal Review: The Genius, Mediocrity, and Breathtaking Stupidity That Is Nature is, as far as we can tell, really a beautiful book, full of full-color photographs and new features galore. We also hope it’s funny. We spent so much time on it that we can’t really tell anymore.

If you’re so inclined, it can be ordered now at Borders, Barnes & Noble, Amazon, Target, or an independent bookstore.

It makes a great gift, even for kids (there’s nothing in it you wouldn’t want them to see), as well as a great way to sound smart and well-informed at any public gathering.

Many thanks to all the readers of this blog for their support and to the people at Bloomsbury USA for theirs.

Kindly yours,

Jacob Lentz & Steve Nash