Day 281. The caterpillar and the cocoon

In May 2013 on May 20, 2013 at 9:03 pm

butterflies copy

Tonight’s bedtime story was Eric Carle’s The Very Hungry Caterpillar.


“But how did he get inside that cocoon?”

asked my preschooler.

“He’s too fat to fit inside there!”

I couldn’t make him understand that the caterpillar actually constructs a temporary house around himself; it is a perfect fit.

Just last week at Not Exactly Rocket Science Ed Yong posted a beautiful article on the transformation from caterpillar to butterfly that takes place inside a cocoon (also referred to as a chrysalis).

“Within the chrysalis, an inching, cylindrical eating machine remakes itself into a beautiful flying creature that drinks through a straw,”

writes Ed.

The article was prompted by the recent work from two groups of scientists that utilised micro-CT scans to create 3-dimensional images of what actually goes on inside a living chrysalis (one of the studies is described in this paper). 

The images show that the structure of the insect gut changes very early in the process of metamorphosis, and is followed at later time points by a reorganisation of the tubes which deliver oxygen around the body. The technology is not yet good enough to track how structures such as muscles and nerves are remodelled.

But the images are beautiful nonetheless. Check them out at Ed’s post here.

  1. […] Dr Andy Warren on viewing the limited specimens I’ve managed to catch in my back yard (shown here in an image from Day […]

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