Amidst life’s profligate swapping and sharing and collaborating, one union stands out: the symbiosis of spotted salamanders and the algae living inside them.

Their uniqueness is no small matter. After all, mutually beneficial relationships between species are legion. Our own genomes are suffused by DNA from other organisms—not inherited from common ancestors, but picked up through the drift of DNA across species. There are cellular mitochondria, the power-generating product of some long-ago meeting, and of course microbiomes, those microbes that account for 90 percent of the cells in animal bodies, and aid in all sorts of physiological processes. Walk through a forest and the trees’ roots are intertwined with co-evolved fungi. A symbiotic carpet lies underfoot.

There’s no end to it, yet the spotted salamander—Ambystoma maculatum, to be exact, common to eastern North America—displays something unique. You can see it for yourself: Should you be so fortunate to find spotted salamander eggs in a vernal pool this spring, take a close and gentle look, and note the tiny flecks of green. That’s the algae, Oophila amblystomatis. No other vertebrate has an endosymbiote—an organism living inside it—that is visible to the naked eye*.

One of the first scientists to notice was biologist Henry Orr, who in the late 19th century surmised that the algae did something for embryonic salamanders, though he didn’t know what. By the mid-20th century, researchers had expanded on Orr’s speculations, hypothesizing that algae perhaps fed on cellular waste and in return provided cells with oxygen generated during photosynthesis.

more

http://nautil.us/blog/the-salamander...ning-inside-it