If you're ever gambling on seasnakes, never bet on black. New research reveals that black-and-white banded turtle-headed seasnakes (Emydocephalus annulatus) out swim their pure black counterparts, thanks to a lighter burden of algae. Algal spores settle on dark covered objects and weigh down the black snakes, slowing their swim speeds by as much as 20%, researchers report  online this month in the Proceedings of the Royal Society B. The findings may explain why the majority of sea snakes are banded, whereas less than half of their land-based cousins sport bands. So why do black sea snakes exist at all? A covering of algae may benefit the snakes in some way, the researchers say, perhaps by providing a supply of oxygen through photosynthesis so that the snakes don't have to take as many trips to the surface where predators lurk.