Uncovering the diversity of deep sea anemones in the South Atlantic

SRMP mentor Luciana Gusmao studies deep sea anemones: their diversity,
evolutionary biology, and ecology. Apparently the deep North Atlantic is pretty well studied at least relative to the southern Hemisphere where in the case of the waters off Brazil only one - ONE - deep sea anemone has ever been documented. Until now.

Luciana and her SRMP team, Elena and Sebastian, have in their possession
a treasure-trove of unidentified (and possibly undescribed) sea anemones from off the coast of Brazil. Whatever Elena and Sebastian find from these previously unexplored depths will be a valuable contribution science. The team is very likely to add new localities for species previously known from elsewhere. But it’s possible that they will uncover an anemone never seen before.

So just how do you identify an anemone? DNA always comes to mind, but is probably out of the question at the moment. The anemones were preserved in formalin which makes DNA amplification tricky at best. Next stop: old-school comparative anatomy. In this case, it’s the arrangement of muscle fibers, mesenteries and the study of small capsules found in different body tissues known as nematocyst that help us differentiate deep sea anemones. To examine these features, Elena and Sebastian need to create slides, a lot of them.

I was particularly interested in the histology portion of their work where they can examine the muscle fibers more closely. I’ve been studying biology for nearly 20 years and never had the chance to make a histology specimen. Creating a histology slide starts with extracting all the water from an anemone via a sequential series of ethanol baths of increasing concentration. Once the water is displaced, the anemone is bathed in paraffin wax which penetrates
the tissues. Once cooled, the anemone is trapped in a waxy block. Here Elena and Sebastian shave thin slices either vertically or horizontally making translucent sheets of anemone suspended in paraffin (think deli slicer). The slides are treated with a series of reagents to dye the specimen’s tissue for observation and voila, several hours later, you have a slide showing the anemone’s muscle structure and the process of properly identifying these one of a kind specimens begins.

Specimen trapped in paraffin wax