On starfish (and whether they are zombies).

juanCaptureAgainst all odds, N. fell soundly asleep at seven last night.  In celebration, I slapped together a pizza; K. and I watched “Juan of the Dead.”  Well, the first two-thirds… then we got tired and fell asleep.  But the first two-thirds was pretty good!  And it was enough to make me want to write a little bit about starfish and zombies.

I’m sure you’ve seen one of those embryology pictures before, the things that compare an early-stage human fetus to a developmentally-equivalent mouse, and, hey!  They look very similar!  Well, if you look a little earlier, you’ll notice that there’s a developmental stage where human and starfish embryos look very similar, too.  Squirmy little tadpole-like things, early on.

devbioMy college roommate’s Taiwanese mother used to tell her, “We all come into the world looking like little hamburgers,” implying that all human babies look pretty much the same.  I think.  My roommate’s mother was somewhat eccentric.  But I’m pretty sure it was meant to be a nice, inclusive message.  And you could embrace a little more of the animal kingdom (not that they’d understand what you were talking about) by saying, “We all come into the world as potbellied little fish.”

You’d still be leaving out some critters, stuff like clams, and ants, and crabs, but come on; what fun are clubs if you’re not going to keep anybody out?

Our club is called “Deuterostomia.”  It refers to the way we develop shortly after an egg cell is fertilized; the egg goes through a bunch of divisions to become a discoball of cells called a “blastocyst.”  The cell ball invaginates to form an anus, then it starts to form a mouth at the other end.  That’s what we look like early on.  Humans, mice, starfish.  Sphere with an ass then a mouth.  In contrast to insects and such, whose cell ball starts by forming a mouth, which means they get called “Protostomia,” Greek for “mouth first.”  And I guess “mouth second” seemed like a classier way to describe ourselves than “Protoproktos.”  (To suss that out, think “proctologist.”)

And starfish continue to resemble human embryos for a while.  Bilaterally symmetric tadpole-like larva.  They have a structure called the ciliary band that, in terms of cell localization and gene expression, is highly reminiscent of the developing mammalian central nervous system.  Which is to say they’ve got something quite brain-like.

But then the starfish goes berserk.  Here’s where our zombie action kicks in.  The starfish jettisons its brain.  Re-absorbs it.

I suppose it’s a stretch to say that our developing starfish eats its own brain, although that is the language a lot of people use to describe Tunicate metamorphosis (i.e. sea squirts, which are slightly more related to us humans than starfish [in the phylum Echinodermata] are), and it is an accurate English translation of the scientific term for what happens. “Autophagy,” self-eating.

Serpiente_alquimicaSo, here we are.  With a young starfish going berserk.  It eats its own brain.  It eats its own everything, all except its mouth.  It does this through proteolytic cellular degradation, not spiraling self-consumption like Ouroboros, although that myth is a pretty dramatic evocation of why the mouth might eventually be all that remains.

From that mouth, arms emerge radially outward.  The starfish develops an endoskeleton, but its outer flesh is thin and soon dwindles, leaving behind a hardened spiny exterior, taut epidermis barely covering its bones.  And (let’s refrain from thinking about why this was tested and written up in a scientific publication) starfish can sustain major injuries like repeated stabbing or limb-yanked tearing and will keep shambling along.  And, right, over time, missing limbs regenerate.  Or sometimes a limb fragment alone can spawn a whole new starfish.

We’re getting pretty zombie-like here, in my opinion.  And then there’s the way their nervous systems work.  Since they’ve already eaten their own brains, starfish have no centralized decision-making capacity.  They’re spurred on by desire, by hunger primarily, this way or that.  If a foot senses food to the east, east it goes!  The rest of the starfish is dragged along until the whole organism starts cooperating on that single, mindless goal.

Just like you would’ve expected (if you’ve been training yourself by watching zombie movies, that is), when fighting an army of starfish your best bet is to sacrifice a friend in order to create a diversion.  Or, wait, I meant “Valiantly charge forward in order to distract them all and save your friends.”  Don’t worry, friends!  I’m not planning to sacrifice you in order to save my own hide!

Of course, starfish aren’t exactly like human zombies.  Like, okay, most zombie movies have a scene where the protagonists are trying to slam a door shut, but the zombies are grasping through with their arms, clutching at the air and trying to force their way in.  Starfish wouldn’t bother doing that.  If the zombies were like starfish, they would simply yaw wide their jaws and spew their own stomachs through the crack in the door, engulfing and digesting the doomed protagonists at a distance.  After a few minutes they’d retract their stomachs, slurping up the slurry of proteolysed flesh, and leave behind a pile of bones in the otherwise empty house.  Time to find new victims!

But, right, except for the minor difference of starfish being more horrifying than what we’ve come to expect from movies, starfish are basically zombies.