Salamanders and the Sun

I just love spring.  It is so exciting to watch everything wake up and start growing.  

I can’t imagine that I will ever stop being amazed that things can take carbon dioxide from the air, water from the soil, energy from the Sun, and make sugar. This time of year it seems like everything is doing it: pine trees, lilac bushes, evergreen woodferns, spring beauties, algae, and salamanders.

Recently, I took a nature walk (which takes twice as long as a hike) up the St. Peter’s Dome trail. Spring beauties, wild ginger, leatherwood, honeysuckle, and cut-leaved toothwort were in bloom. Wood anemone, Dutchman’s Breeches, and several others were close. These plants are taking advantage of the sunlight before leaf-out shades them out.  They complete their entire annual cycle in just a month or two. By midsummer, sugars produced through photosynthesis are stored safely in their roots, flowers have spread their seeds, and leaves have withered back into the soil. Their short appearance above ground is what earns them the title “spring ephemerals.”

Vernal pools are another ephemeral spring phenomenon. Puddles of snowmelt and spring rains form in low areas, and may last a few days, or a few months.  The key is that they dry up eventually, which makes them poor habitat for fish.  Amphibians, like frogs and salamanders, take advantage of this lack of predators, and lay their eggs in the relatively safe, warm water. Their young then feed on mosquito larvae and other insects who also use the pools to breed.

One vernal pool, near the old quarry at St. Peter’s Dome, has several jelly-covered clusters of spotted salamander eggs! Spotted salamanders are common throughout the eastern U.S. Their large size, blue-black skin, and bright yellow spots make them a charismatic critter.  Adults mostly live in moist leaf-litter and under rotting logs. In the spring, they journey by the hundreds to vernal pools to mate and lay eggs.

The jelly around the eggs keeps them from drying out, but it also inhibits oxygen diffusion into the egg. Scientists have known for a while that the salamanders have a symbiotic relationship with algae to help address this issue. Algae on the jelly use the carbon dioxide and nitrogen-rich waste emitted by the developing embryo.  In return, the photosynthesizing algae give off oxygen that the salamander embryo can use. The algae form a natural oxygen mask!

Recently, scientists have discovered that spotted salamanders actually have a much closer relationship with algae. These algae are, in fact, located inside cells all over the spotted salamander's body. There are even signs that algae may be directly providing oxygen and sugars to the salamander cells that encapsulate them. An electron microscope allowed researchers to see salamander mitochondria (the powerhouses of cells) gathered around alga like it’s the dining room table! This is the first ever documentation of photosynthetic algae inside the cells of a vertebrate animal.

Somehow, the salamanders have convinced their immune system to not kill these foreign algae cells.  Scientists think that salamanders’ ability to regrow their limbs may have something to do with their ability to host foreign algae cells within their bodies. Scientists even found algae in the oviducts of adult female spotted salamanders, suggesting that the algae can be passed from mother to offspring.

Now salamanders can harness those little photons from the Sun even more efficiently!

Life will never cease to amaze me.