Terrestrial ophiuroids
Introduction:
 The brittle star Amphipholis squamata. |
The aim of this project is to create my own army of predatory terrestrial brittlestars to carry out my bidding. While echinoderms are notoriously salinity-restricted when compared with many other marine invertebrates, I believe that we will eventually be able to produce ophiuroids that are fully capable of living only on land and looking appropriately creepy while traveling in herds.
biology brittle-star evolution marine ocean ophiuroid organismal-biology
#Comments: 2
I'd like to join this project!
I think Amphipholis squamata might be a good choice to start with because 1) it doesn't have a larval stage, so it wouldn't have to run back to the ocean to breed (and you wouldn't want your brittlestar army limited to walking distance from the ocean), and 2) since it lives in Argyle Creek (in San Juan Island) it is probably exposed to a fair range of salinity variation, so it should be okay at dealing with water balance. It's rather small, but that should mean short generation times, which would be good.
One thing I like about this project (aside from just wanting there to be terrestrial ophiuroids) is that it gets at some deep evolutionary and physiological questions. For example, why did some animal groups diversify on land and in freshwater, whereas others stayed strictly marine?
Echinoderms do not generally have high tolerance for salinity variation, and typically they do not regulate cell volume (as far as I've read). However those are also true for at least some species in taxa (e.g. mollusks and arthropods) that have diversified on land. The tube feet that many echinoderms use to move may not be great for terrestrial locomotion, but some echinoderms use spines to move, and brittlestars use their arms, which are supported by a hard skeleton. My guess is that there is no single factor that prevented echinoderms from colonizing land, but perhaps many factors together.
A short term artificial selection experiment (e.g. for tolerance of low salinity or aerial exposure) might tell one something about what factors are easier to change.