Featured Image Credit: Claire Goiran
By Kira Krall
Pacific-dwelling turtle headed sea snakes were all found with bold black and white stripes as recently as 50 years ago. Now, a population of sea snakes in a polluted area near Brisbane, Australia are solid black.
This “urban melanization”, or turning black in response to changing environmental conditions near a city, is common among insects and other invertebrates. The most famous example is England’s peppered moth. While this urban melanization had more to do with blending into the soot-covered environment, our sea snakes have a different motive.
Rick Shine and his team from Queensland University knew that pollutants like lead bind easier to melanin, the pigment found in dark skin. They followed their hunch and tested 17 skin sheds left behind by the darker Brisbane sea snakes. They discovered a total of 13 trace elements. Lead, manganese, zinc, cobalt, and nickel had the highest concentrations. Shine reported that similar concentrations in domestic animals causes serious health complications.
This is an impressive pollutant regulation method even though it seems counterintuitive. Sea snakes shed their skin just like their terrestrial counterparts. As they shed their skin, the trace elements that have built up shed along with it.
Shine and his team found yet another way life on Earth is adapting to excessive pollutants. Susana Clusella-Trullas at Stellenbosch University is conducting a follow-up study that will compare survival and reproductive rates of black turtle headed sea snakes versus the traditionally striped ones. This resilience to pollutants is promising, but there’s only so much a species can take before we lose them forever.
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