Born this way: part 2

"I'm beautiful in my way
'Cause God makes no mistakes
I'm on the right track, baby
I was born this way"
- "Born this way" by Lady Gaga

Another one of the organisms I'm finding in my samples is Clione limacina, which is a pteropod or "sea angel." We actually collected a very large adult of this species in one of our samples, which I didn't even need a microscope to see. As I'm going through the larval samples in more detail now, I'm finding lots of younger pteropods, including their polytrochous larvae.

Polytrochous larvae of Clione limacina. Arrows mark
ciliary bands. Two individuals are not to scale.

The root word "troch" means wheel, and it refers to the bands of cilia (cellular hairs) that help larvae swim. As the cilia beat, it looks like a wheel turning around the larva. The polytrochous larvae of Clione limacina have multiple ciliary bands (poly = many), which I can see distinctly in my larval samples. As Clione individuals grow, ciliary bands are no longer sufficient to propel them through the water, so they develop the "wings" that adults use to swim and which give them the name "sea angels." 

Limacina helicina, the shelled pteropod. These two
individuals are to scale with one another.

Clione limacina has a very specific diet - the "sea angels" are predators on another species of pteropod, called Limacina helicina. Both Clione and Limacina are types of swimming snails, but Limacina still has a shell. Shelled pteropods are sometimes called "sea butterflies," but I've actually heard them called "sea devils" in some languages. Since Clione eats Limacina, I guess that means sea angels eat sea devils!

There are plenty of Limacina helicina in my samples, both young, small individuals and larger adults. Individuals belonging to this species are easily identifiable by their clear shells, which have a tight spiral to the left.

It's exciting for me to find young pteropods of two kinds in my samples! So far, my data show active reproduction of multiple species in the polar night.