Black and blue and wet all over

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On the weekend our landlady and her son were here to shut down the swimming pool for the year. Neither Dan nor I had used the pool since moving in, although had it been an average summer with lots of glorious sunshine to warm the water and hot, sticky temperatures to inspire me to dive in, I probably would have been in there most days. As it was, we’d enjoyed the frogs that had moved in but didn’t try out the water ourselves – too cool for the weather. It takes a lot of energy and effort to maintain a pool, and since we weren’t using it, we suggested to our landlady that it might be best just to shut it down for the year.

When they went to clean out the pool filter they found this little guy floating around in the intake area. The son brought it into the house for me, suspecting (correctly) that I might be interested. It’s a Blue-spotted Salamander, Ambystoma laterale. This one was just little, maybe 3 inches (8 cm) long, but even the largest ones only grow to 5.75 inches (14 cm).

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It was probably a youngster from this year. Salamanders start out aquatic – their eggs are laid in vernal pools and they spend the first couple of months of their life in the water. By late summer they’ve completely metamorphosed into their adult state. As adults they are terrestrial, living either in and around damp deciduous forests and swamps, or sometimes found in fields or coniferous woodlands (I think it’s unlikely they would spend their whole life in these habitats, though; probably they are just passing through or staying temporarily). They generally hide under rocks or logs, or sometimes just in the leaf litter. In the spring especially, when the forest floor is damp and salamanders are on the move to the vernal ponds for breeding, but also in the fall when young salamanders are dispersing, I have visions of unintentionally stepping on a salamander that’s hiding under a leaf in the litter.

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Salamanders, like all amphibians, have very thin, sensitive skin. Having been in the chlorinated pool (however mild the concentration) I was a bit concerned for his health, although the frogs seemed to do okay there. Blue-spotted Salamanders use lungs for respiration, but there are some species that breathe through their skin. All salamanders need to keep their skin moist, and secrete a mucous layer that helps trap moisture, but also acts as a barrier to salt loss when they’re in the water (otherwise their bodies salts would disperse through their skin, by osmosis, into the relatively salt-less freshwater).

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We have one small pond on the property, tucked a couple of fields back, hidden in a patch of trees. It’s less than a foot deep at this time of year, though I don’t doubt it will be considerably fuller in the springtime. I decided to take the salamander back there, both so that it was away from the pool (and the dog), but also so it was nearish to water should it want it, even though as adults they don’t actually spend much if any time in water in the non-breeding season. Presumably if it stayed in the area it would have a head start on migrating to the pond in the spring.

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When we reached the water I slipped my hand under the surface, and after a moment the little salamander swam off. Even though they spend so little time in the water, they’re adept swimmers, using a side-to-side undulating motion much like a fish or shark. Its long partially-flattened tail probably helps play a role in this movement. Males will also have longer, more flattened tails than females (which leads me to wonder if this is a female). Presumably the males need more control in the water when they’re trying to win over and mate with a female in the spring.

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The salamander, once in the water, didn’t go far. Clearly it thought the water every bit as cold as I did. After a moment it seemed to be curling up into a fetal position, so I lifted it out again. I was surprised at the temperature, since it is late-summer after all.

You can really see just how spotted it is, and where it gets its name. There is also a similarly-patterned species, the Jefferson’s Salamander, that doesn’t occur here but is found through much of the Blue-spotted’s range. The Jefferson’s is dark with blue speckles rather than blue spots. Where the two overlap they hybridize regularly, producing a non-species labelled “Ambystoma platineum“. These hybrids are triploid – that is, they have three sets of genes instead of the normal two – and are all females. They reproduce gynogenetically – they will mate with males, but the male’s sperm only acts as a trigger to the egg to start dividing; it contributes no genetic material itself. As a result, the hybrid’s offspring are partial clones of their mother – they are diploid, with two sets of chromosomes that are identical to two of the three of their mother’s.

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I set the salamander back out on the leaf litter, since clearly it had no interest in being in the water. I left it there, hopefully to go off and find itself a good place to hole up for the winter. It will need to burrow down into the sandy soil some 18 inches (45 cm) or so to get below the frost line. It will reemerge in the spring, triggered by the first spring rains, often marching across snow to reach its still mostly-frozen breeding ponds. I haven’t ever witnessed this spectacle, but I’m going to try to see it next spring. Maybe, among the individuals in the meltwater at the pond’s edge, this guy will be there.