How Do Sea Urchins Work?

Spiny on the outside and gooey on the inside, sea urchins are a weird and wonderful animal -- and delicacy. Learn more about them in this episode of BrainStuff.

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Episode Transcript

Speaker 1 (00:01):
Welcome to brain Stuff production of I Heart Radio. Hey
rain Stuff, Lauren voc obam here. Whoever it was that
first came upon the sharp, spiny body of a sea
urchin and said, Hey, let's crack this bad boy open
and see if the orange goo inside tastes good. Deserves
a gold medal in bravery and sheer determination. The sea

(00:23):
urchin is a small, spiny sea creature called a kindaderm.
Sea urchins, along with all members of the Philomicina dermata,
are found only in the ocean, a particularly unusual quality
as a large number of aquatic animals tend to take
up residents in lakes and streams as well. Sea urchins
most often can be found in shallow water and even
carpet the sea floor in some areas. Commercial sea urchin

(00:46):
fishing began in Japan soon after World War Two, before
spreading to the entire Pacific rim by the nineteen seventies,
and within two more decades the practice would spread to
the Atlantic region. We spoke with Bob Stenic, professor of oceanography,
marine biology, and marine policy at the University of Maine.
He said the global peak and sea urchin harvests occurred
around and has declined ever since. In many places, it's

(01:10):
a poster child example of over fishing. In the year
two thousand, twenty million pounds that's about nine million kilos
of sea urchins were harvested in California and sold to
markets in Japan. But if you've never tried it, you
might be curious about what all the fuss is about.
We also spoke with David Glass, accomplished dessert chef, self
described sea urchin fanatic and father to the author of

(01:33):
today's episode. He has a few choice words, but it
comes to consuming these bizarre little creatures. Quote the brilliant
orange color, slightly fermented, aroma, and solidity, suggesting a catastrophic
explosion of flavor in your mouth. Proceed your first taste.
That first taste is sticky, oceanic, sweet and fermented, and
everything else that makes up the taste, known as umami.

(01:55):
Poetry starts to flood your brain. In Layman's terms, see
chin called uni in Japanese, tastes weird but fine. It's gooey, runny, funky, savory,
but with a hint of sweet and salt, with a
texture somewhere between an egg yolk and jello. It is
a very very unusual taste, but when prepared right provocative

(02:17):
after humans, The sea urchin's second biggest predator is one
of its own fellow aquinoderm that we're all familiar with,
the starfish. If you think starfish are beautiful, get ready
to be kind of horrified with this graphic nugget. The
starfish will wrap itself around the sea urchin, then evert
their stomach out of their body onto the sea urchin
in order to dissolve the shell with their gastric juices

(02:38):
and eventually get to the tasty flesh within. And sea
urchin's own eating habits are just as fascinating. It has
a circle of five sharp teeth on the bottom of
its body and yes, this looks like something out of
Stranger Things that it uses to scrape algae and collect
kelp off of the rocks it lives on, and can
even use them to burrow into the rocks for a

(02:59):
better hold on the ocean floor or to make itself
a little hideaway. But they're not vegetarians. They'll eat other
animals or each other if they get the chance. Scientists
also believe that some species of sea urchins don't age,
meaning they don't die unless they're killed by something, and
they don't lose the capacity to reproduce. Stenic said, a

(03:19):
sea urchin's body plan is pretty unique. One could say
it's a hollow limestone sphere made out of numerous hexagonal plates,
sort of like a geodisc dome, with spines that make
it look like a pincushion. They move slowly using numerous
small tubular section devices called tube feet. These tube feet
are strong muscles the protrude from the ends of the spines,

(03:40):
which they can attach to rocks or coral, allowing them
to move over the sea floor and those little spines.
Think of them as sharp feet that are just achin
to pierce your skin. While it's certainly not pleasant, Stenic
assures that stepping on a sea urchin is not deadly,
and he has to date never heard of a fatal
case to an accidental trampling. Still, if you're worried about

(04:03):
stepping on one of these guys, well maybe wear rubber
soled shoes and try not to prick on the feet
by one of these spines can cause damage to the
skin and sometimes even the bone inside a few species.
Spines can be venomous, but not so much that it
would be fatal to humans. The worst that can happen
is a potential allergic reaction or further injury from trying
to remove the spine. Instead of tugging at it, use vinegar,

(04:26):
which will dissolve the spine and leave behind only the
distant memory of that time that you stepped on a
living pin cushion. So, whether you accidentally come upon these
spiny marine creatures on the sea floor via your foot,
or take a bit of its insides brushed with soy
sauce over rice, you really have to appreciate the sea
urchin for its unbroken commitment to staying weird. Today's episode

(04:52):
was written by Jeremy Glass and produced by Tyler Clang.
Brain Stuff is a production of I Heart Radio's How
Stuff Works. For more in this and lots of other
weird topics, visit our home planet, how Stuff Works dot com,
and for more podcasts for my heart Radio, visit the
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