The Mad Hatterpillar

June 15, 2013 5:34 PM

How to get ahead. Again and again. Moths and butterflies are just flying gonads that make new caterpillars. Caterpillars are feeding machines with one primary purpose: eating enough food to build the body of a future moth or butterfly. A caterpillar stuffs itself with food, but eventually is limited by its exoskeleton, which is rigid and can’t grow. ‘Pillars deal with this by splitting their external skin, shedding it, and making a new, bigger exoskeleton so they have room to grow. For some reason, this species of moth caterpillars keeps their heads and build themselves a strange “hat” that gets taller as they grow.
posted by srboisvert (16 comments total)

larvae of a Gum Leaf Skeletoniser moth

Most bad-ass moth name EVAR.
posted by briank at 5:39 PM on June 15, 2013 [1 favorite]

The balloon head catapillars are worth a click too.
posted by Artw at 5:51 PM on June 15, 2013 [3 favorites]

The reason for the retained heads could be an absence of selective pressure rather than a positive adaptation.

Most insect molting goes in at least two stages, with abdomen/legs being the first and head being the second. Random modifications of head capsule shape probably ended up leaving an anchor for the old head capsule, preventing it from dropping off during the normal stresses of molting. The if the interstitial fluid secreted between exoskeletons during molting dried shortly after, acting as a protein-based glue, then viola. Stacked Hats.

If there was no evolutionary disadvantage to having them there they probably just stayed. It breaks up the profile of the animal a bit, so it might make it less recognizable as prey to some other animals. Maybe.

Speaking of stacked hats, have some stacked cats.
posted by clarknova at 6:08 PM on June 15, 2013 [3 favorites]

What if the head retention evolved to mimic another creature that no longer exists? Perhaps some wildly dangerous eucalyptus resident that was wiped out by a cruel twist of fate, leaving only a faint ghost whispering in the hollow husks of caterpillar skulls...
posted by Mary Ellen Carter at 6:28 PM on June 15, 2013 [20 favorites]

The stacked hats look like miniature koalas, obviously, the natural enemy of gum leaves.
posted by Joe in Australia at 6:37 PM on June 15, 2013

That is an adorable caterpillar.
posted by medusa at 7:10 PM on June 15, 2013

Those stacked heads look like the sting of an Australian scorpion.
posted by jamjam at 7:43 PM on June 15, 2013 [4 favorites]

As I suspected, the adult of this species is quite drab. There seems to be a bias towards having spectacularly weird caterpillar stages, as in the case of the Monkey Slug or Hag Moth, and fantastically mundane adults.
Worst of all may be the rusty tussock moth, where both sexes have awesome caterpillars, but the females are wingless immobile lumps after they metamorphose. This is "worst" in the sense that you spend some time rearing the caterpillar, hoping for the elegant adult to emerge, and but no, you just get a bit of fuzzy cuticle covering an giant ovary with legs.
posted by Cold Lurkey at 7:59 PM on June 15, 2013 [8 favorites]

Monkey Slug

Is that from Earth?
posted by Artw at 8:05 PM on June 15, 2013 [2 favorites]

Moths and butterflies are just flying gonads that make new caterpillars.

Except for flying, people aren't really that different here.
posted by tylerkaraszewski at 8:22 PM on June 15, 2013 [3 favorites]

.... they pose a photographic challenge in that, undisturbed, they adopt regal poses... but with the slightest disturbance.... they either flatten out and vomit green fluid which tends to spoil the shot, or they throw themselves into space on a silk thread lifeline to resume their positions when danger has passed.

I have found my new Spirit Animal.
posted by The otter lady at 10:07 PM on June 15, 2013 [14 favorites]

just flying gonads

So, is Second Life still going?
posted by pompomtom at 10:19 PM on June 15, 2013 [6 favorites]

These caterpillars are native to Australia and eat eucalyptus trees.

How big are these things?
posted by hypersloth at 11:22 PM on June 15, 2013 [4 favorites]

Mary Ellen Carter, you deserve a ribbon for Wonderfully Eerie Thought of the Year.
posted by Anything at 12:01 AM on June 16, 2013 [4 favorites]

Have you read Dune, hypersloth? Yeah.
posted by panaceanot at 1:33 AM on June 16, 2013 [3 favorites]

I thought the heads looked like a tail that had died and dried out. As if the beast was ill. So perhaps those stacked heads look like something unsuitable for lunch.
posted by Goofyy at 10:29 AM on June 16, 2013