Saturday, January 19, 2013

Walkabout Missive #4 OR Viva La Hermit Crab Proletarian Revolution!

After all the New Zealand excitement was over, you'd think that was enough, right?  Wrong! Time for Costa Rica!  

You're in luck with respect to my Costa Rica trip:
  1. Because the camera got broke by a vicious Marbled Wood Quail (Figure 1) immediately upon taking the camera out to take the first picture of the trip, and:
  2. Because I actually saw almost no marine organisms. And I have 0 pictures of marine organisms.
Figure 1. Marbled Wood Quail.  Not my picture, because, as you can clearly tell, these birds socialize to plot the demise of tourist soul-capturing devices such as the nefarious Panasonic Lumix Zs20s. 

Oh but don't even for a second imagine that you are off the hook.  Because you are about to have to endure my amazement at seeing:

A Hermit Crab Conga Line!

Figure 2. Hermit crab conga line! At first I thought I made that term up and no one should repeat it, but now I've read it elsewhere so that's officially what this is called. Also, apologies that this picture was clearly taken by my phone. Costa Rica had its revenge however, and oxidized the contacts on my phone's charging port and now the phone won't turn off. You win, tropical humidity, you win.
Ok, so check this out (Figure 2). There are at least 4 hermit crabs (1) in order of descending size lined up trying to forcibly evict the largest hermit crab (not visible because it's hiding quaking in that luxury shell). The idea is that it's dangerous for a hermit crab to be shelllllless because the abdomen, which you typically can't see, is all gross and vulnerable (eew), and because they basically become french fries to birds when they aren't protected by their shells. So, in this efficient system, they latch onto someone who has a more spatious shell equipped with all the modcons, and wait for the bloodshed to start. No, really! Well, maybe "bloodshed" is a bit hyperbolic, but "Conga Line" is rose-tinting it for sure. This is survial on the line here and it is a scenario of a social enforcement of reappropriation/liberation of valuable goods (2)


I'd have taken a video of this, but the process takes forever, because that 1% guy in the big shell is smart and just tries to wait for the violent 99% mob to tire themselves out and get bored and go back to taking soma and watching reality TV shows.

I had totally heard of this phenomenon, it's not new to science. But I didn't really believe it could be true - sure maybe someone saw some hermit crabs in a group once somewhere and projected some story on them, but NO, this was happening ALL OVER THE BEACH. There is such a high density of hermit crabs on these black sand tropical beaches (3) that shells are likely in short supply.  

These crabs had the COOOLEST SHELLS (Figs 3 & 4), but I never saw the actual snails that made them. 

Figure 3. Turritella leucostoma (I think?).
I have got to start adding scale bars to my shell photos.  Bush league, Grason.

Figure 4. Whelk.  You'd think since I study whelks I'd be better at identifying them,
but my current resources - thanks Google images, don't really give me much to go on.

OK, that's all I have to say about hermit crabs, but check out these awesome other arthropods we saw!

Figure 5. Lady Elephant Beetle!  With finger for scale.  This one was dead at the visitors center at Corcovado National Park, but freshly dead - she had goo still all up in her.

Figure 6. STAG BEETLE (!!!). This doesn't look impressive except the nail
head is about 1cm across for reference. This guy accepted our eager invitation
to dinner one night, hence the napkin, but evidently didn't feel
welcome and took off almost immediately after.

Figure 7. Check out those sparkly baby blues!
Figure 8. Whiptail Spider (Amblypigi) This was our nighttime bathroom buddy.  Evidently he's only a little guy (though easily probably 6-8" across at those whips) because we saw several much larger on a nighttime hike.  We also had some bats take up residence in our bathroom closet each night. 

Sleep tight! Don't let the giant beetles bite!

References and miscellany:
(1) You'll recall from when you got your first pet hermit crab from that sketchy boardwalk souvenier shop that pet hermit crabs are actually not marine, they are land crabs, and will die if you submerge them in water.  Though they do require some water source to keep their gills wet so they can breathe. There are indeed marine hermit crabs, we got heaps up here in the PNW, but the ones crawling around on the beaches in Costa Rica are terrestrial.
(3) Not to make you jealous, but srsly, these beaches were tropical commercial beautiful. 

1 comment:

  1. Worlds Deadliest!