Finding a lady slipper in the woods is a magical Maine springtime moment. The pink bulbous blossom stands out in the moist woodland understory. Lady slippers are a bizarre orchid species with their dangling slipper-like flowers. There are a few different species of lady slippers, one of which is the prized and protected species – the pink lady slipper. They are protected because they are a particularly slow growing flower and it takes them several years to mature and reproduce. They are designated as a “species of special concern” under the Native Plant Protection Act and collecting them is strongly discouraged, but it is a myth that it is illegal to harvest them. But, there is another lady slipper that isn’t so rare.
Perhaps less thought about, however, is the seaside lady slipper, Crepidula fornicata. This one has the advantage of being edible – while not commonly, but it can be steamed and served much like other shellfish. The lady slippers that are found along the seashore are a species of snail much like the more familiar periwinkles and limpets that dot tidepools. One difference is that they are filter feeders rather than snails and limpets that scrape the rocks for their food. For this reason, they are usually found lower down in the intertidal below the tide line.
Lady slippers are usually pretty small, measuring 1-2 inches across, and have a rounded pinkish back. Crepidula means boot and fornix means arched, as they are shaped somewhat like an arched boot on top, But, it is their unique shape underneath that gives them their distinct common name. There is a half a shell of sorts that partly encloses the bottom part of the shell, coming about halfway back as if to make a little shoe or lady’s slipper. This is a neat design because, when they want to feed, they can open up a little bit of their shell and let the water flow in so that they can trap tiny particles of plankton in their gills. They have tiny hairs inside called cilia that help them to move the water along.
Lady slippers can easily be identified by their distinctive shape underneath if they are taken off the rocks, or if you find an empty shell. But, another way to ID them is by the strange way they live together. Lady slippers grow in lumpy heaps of many individual snails stacked on top of each other. This might be on the rocks, or it might be on the top of another animal’s shell – a horseshoe crab being one of the common ones you might see at this time of year. The particularly weird thing about a pile of “lady” slippers is that some are ladies and some are males. The larger females are at the bottom with the young males on top. Or, at least that’s how it starts. As they get bigger, the males turn into females. They are thus classified as sequential hermaphrodites – a bizarre living pattern to be sure.
It turns out that their strange way of forming colonies is actually a clever reproductive strategy. Because the males and females all live together, they don’t have to rely on the usual means of free floating sperm and eggs somehow meeting up in the water. Instead, the female releases eggs that are fertilized right there. Perhaps this is why they are so prolific – particularly as compared to the lady slippers in the forest. This is the time of year for their spawning, so you are likely to see loads of these tiny shells attached to just about anything right now. And, if you keep looking, soon you’ll see the piles start to form. So, keep your eyes out for the lady slippers of the sea this spring as well as those in the woods.
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