Author: David Bradley

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.

Hunger for protein and salt, and a fear of cannibalism, drives the
mass migration of Mormon crickets across western North America, says Stephen Simpson of the University of Sydney, Australia. Mormon cricket swarms, sometimes millions strong covering more than 50 miles in a season. They destroy vegetation in their path and are a severe hazard to drivers.

Locust plagues of Biblical proportions have been with mankind, since, well, Biblical times, at least(!) and usually these creatures swarm in response to a shortage of food. The precise nutritional triggers for the migrations of Mormon crickets though have remained a mystery. Now, field observations by Simpson and his colleagues offer an explanation.

It seems that total starvation is not the driving force, rather migratory crickets preferentially feed at experimental protein-rich and salt rich sources. In the field, crickets were frequently observed feeding on carrion and on each other. When the movement of crickets was experimentally impaired (immobilized by gluing and/or tethering), these insects became targets for cannibalism by neighbouring crickets. These results thus reveal a different model for collective motion, with the crickets’ migration in effect a forced march, the researchers say. The constant threat of cannibalism from the rear appears to push the crickets’ movement as much as the need to find protein and salt pulls it.

Simpson and his colleagues publish further details of their findings today in the online edition of PNAS.

According to The Register, levels of the “satisfaction” hormone prolactin do not reach as high a peak following manual stimulation in men as they do after purportedly procreational activity with a partner.

The original research published in Biological Psychology could explain what The Register describes subtly as a “niggling dissatisfaction” following the former approach to gratification. Needless to say, the remainder of their article is anything but subtle and the link above should only be followed if you’re feeling up to blatant sexual innuendo.