Algal Symbioses & Green aliens?

Molecular tools are allowing biologists to investigate more closely a a long-known symbiotic relationship between an algae and a most unusual partner, salamander eggs. As you know most amphibians lay their eggs in still water, and algae grow inside these salmander eggs making them green (the spotted salamander in N. America has eggs like this too). Metabolic waste products, carbon dioxide and nitrogenous compounds are raw materials for the algae and the photosynthesizers give off oxygen, thus the symbiosis. But how do the algae get there inside an egg? Algal genes in salamander DNA suggest the algae may be inherited, passed on from mom to offspring (assuming the algae go with the egg). Algae live inside lots of animals: hydra, mollusks, sea slugs, corals, but this is a vertebrate, a supposedly higher animal. And you know what that means? Green aliens are a complete possibility! Of course, Star Trek fans already knew about the slave women from Orion. What great slaves! So cheap to feed and clothe! HT to Thomas' Plant-Related Blog.

Really green animals

Generally organisms are green for one of two reasons: they use chlorophyll for photosynthesis, what the Phactor calls "really green", or they have a green-pigmented camouflage, which produces a pretty clear dichotomy between plants and animals. Down deep in the animal clade where you begin to get close to the never never land of unicellular organisms where distinctions like plant and animal do not work, you find some exceptions: green hydra, green clams, green sea slugs, green corals, and all of these harbor symbiotic algae in their bodies, but not in their cells. So of course once you get used to making such pronoucements, an exception pops up and forces you to go find the bloody thing in your book manuscript and add a dinged dang endnote! Algae are known to live within amphibian eggs in the "gell" surrounding the embryo, which might be considered intracellular, but maybe the Phactor misremembers something about amphibian eggs. The algal cells take up nitrogenous waste and get a nice wet habitat. But now the algal cells have been found inside a salamander embryo itself, the first truly cholophyll green vertebrate, although still lacking vertebrae at that stage of development. Does the embryo gain some benefit from the algal symbiont in addition to the removal of nitrogenous wastes? Does the algae share its photosyntetic products with the salamander? Maybe this will get those darned vertebrate physiologists to learn something about photosynthesis.