Yesterday was a beautiful day. The temperature was in the 60’s and it was just a bit cloudy- enough to temper the harshest parts of the afternoon sun. And that sort of weather made it a great day to go salamandering. Salamandering, as a word, just sounds good. I’m a fan of semi-made-up-awkward words like that. They just roll off the tongue.
Anyway, I went salamandering yesterday out near the Catawba River. As I was walking around, I came up this little one underneath a rock in one of the streams. This little salamander is a Dusky Salamander. They are tiny little guys. This one was probably only about 2.5 inches long and that’s the adult size. You can tell it’s an adult by the color patterns and by the fact that she’s sitting there with a clutch of eggs! Those eggs are on the underside of the rock. I was gently overturning some rocks in the stream when I found her and her eggs there. What a good mother, too! Unlike other salamanders that I found yesterday, she stayed in place when she was exposed. I took some pictures and then gently replaced the rock so that she could sit there with her eggs for the rest of the day.
The question, though, is why didn’t she move? Salamanders aren’t normally the poster child for parental care, but this individual was definitely putting herself at risk to hang out with her eggs. It’s possible that she was there telling them stories and singing salamander lullabies, but even the threat of exposure didn’t force her to run off- and had I been a predator that could have ended badly. What that says to me is that there’s got to be some reason (some benefit) for giving that kind of parental care.
Conveniently, I’m not the first person to have thought about this topic. One researcher has studied parental care in a similar species of Dusky Salamander and found evidence for several sets of benefits that this kind of egg guarding provides.
While this particular paper focusses on one factor, the author cites previous work of his that addresses some other benefits of parental care. I’ll hit them all briefly. 1. Defense against egg predators. Now she couldn’t have done much against me if I had decided to take her eggs, but she may have been able to chase off other salamanders. There were some larger salamanders (Blackbelly Salamanders) in that stream that do eat smaller salamanders and certainly could be eating eggs, if they’re available. 2. Reducing infection. Mom could spend time cleaning the eggs and preventing growth of fungi or other parasites on the eggs. 3. Increasing oxygenation. By moving either the eggs or the water around, mom could provide those little developing babies with more oxygen. 4. Prevention of desiccation. Mom could reduce the rate at which the eggs lose water.
In the end, what does all this mean? For a little salamander like the one in the stream, it means that by staying there and taking care of her eggs, she may end up with more eggs that actually hatch successfully. If she takes really good care of them, she may end up with quite the little. Eat your heart out, Octo-mom. This little salamander has got you topped.