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On the Origin of Species: Lileep and Cradily

1 byte added, 08:39, 10 August 2010
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So, if most ancient crinoids remained fixed in one place with their stems, and most modern crinoids can move around freely, what might have prompted this change? Well, first we have to consider why a creature might choose to be immobile in the first place. Sedentary crinoids are descended from free-living animals, and indeed, their larvae are able to swim before attaching themselves to the sea floor. So at some point, it must have been beneficial for these creatures to take up this particular lifestyle. Why might this have happened? Well, we only need to look at nature to see that staying still can actually be an excellent strategy. It certainly works for plants and fungi. As long as food is always within reach, staying still means that an organism doesn't have to expend energy on movement, or waste resources on making complicated muscular systems that it doesn't need to use. It can simply stay where it is, and put all of its excess energy into reproducing. This was evidently a successful strategy for the prehistoric crinoids, because 300 million years ago they were thriving, with countless species colonizing the sea floor at a wide range of depths.
 
One big disadvantage to staying still, however, is that you become an easy target for predators. Fossil evidence shows us that creatures such as {{wp|sea urchin}}s began to view the stationary sea lilies as an easy meal: maymany crinoid fossils from the {{wp|Triassic period}} show evidence of teeth-marks! It seems that this is why some crinoids became motile again. Some, such as the feather stars, have become reasonably adept swimmers: not especially quick or graceful, but enough to make a break for it if things seem to be getting dangerous. Other species have been seen to slowly walk along the sea floor using their multiple arms. This gradual progression towards motility seems to be referenced in the Pokédex entries of Lileep and Cradily, too... while Lileep is stated to be immobile, numerous references are made to Cradily moving around (albeit inelegantly).
 
It was recently discovered that even crinoids with stems - that usually remain fixed to their spot no matter what - can move if it becomes necessary. [http://www.youtube.com/watch?v=7V_px48dob8 Archive footage taken from a submersible] shows a crinoid with a snapped stem inching its way along the sea floor on its arms. Perhaps this is how the ancestors of modern motile crinoids started out, before doing away with their stems altogether. Either way, it's a powerful reminder that though they may look like plants, these lilies are indeed animals: animals that can eat, think and move... if the mood takes them.