Abstract/Summary

As we, humans, charge through the twenty‐first century with our pioneering technology and global interests, we threaten to destabilize Earth’s natural processes and destroy biodiversity before fully understanding what is being lost. New species are still discovered, even as thousands go extinct, and science is in a race to deliver crucial knowledge that can inspire conservation. This thesis explores ecological aspects of a recently described sea snake Hydrophis platurus xanthos. Given its vibrant canary coloring and unusual behavior, xanthos, as it’s come to be called, is sure to spark curiosity and wonder in readers. Chapter 1 of this thesis provides an introduction that chases the evolutionary trail from the emergence of reptiles in the Carboniferous to the first diving elapids of the Miocene before detailing the physiological and ecological characters of H. platurus and its journey across the vast Pacific Ocean, eventually giving rise to a xanthic (all‐yellow) population in Golfo Dulce, Costa Rica. Chapter 2 combines survey sightings with bathymetric data to investigate the geographic partitioning of xanthos from its pelagic relatives. Chapter 3 considers several hydrographic conditions that govern habitat suitability for xanthos and measures its range. Chapter 4 looks at the taxon’s behavioral patterns and activity cycle, revealing yet another remarkable example of divergence. Chapter 5 applies distance‐sampling techniques to compute the first total population abundance estimate for xanthos from which future trends can be assessed. Finally, Chapter 6 explains the comprehensive value of our findings, which confirm the Golfo Dulce yellow sea snake to be a unique evolutionary organism. This work provides evidence to promote protection of Costa Rica’s endemic marine reptile as a biological treasure, and going forward, has set us on course to examine whether xanthos is a separate species.