TL:DR – Short news article from 2006 about salamanders. The headline alludes to a lyric from a song by the band Genesis, The Carpet Crawlers.
Salamanders can transform from an aquatic juvenile form into their terrestrial, adult form only if the stream bed on which they develop is of the right nature. A study published today in the journal BMC Biology reveals that the Oklahoma salamander Eurycea tynerensis metamorphoses into a terrestrial adult form in streambeds composed of fine, tightly packed gravel but stays in the juvenile form in loosely packed streambeds composed of large particles.
The study by Ronald Bonett and Paul Chippindale from the University of Texas at Arlington, Texas, USA, exemplifies how small habitat differences can influence developmental patterns and morphology, they also suggest that such microstructure changes could influence a species’ evolution too.
Bonett and Chippindale explain that large gravel creates porous streambeds with large spaces between particles, where aquatic paedomorphic salamanders can access sub-surface water during dry months. However, if these spaces are filled in by small particles, metamorphosis is the only way they can survive when surface streams dry-up.