Crepidula fornicata: descriptive name or tasteless joke?

The name Crepidula fornicata always elicits giggles.  Understandably.  The last place anyone expects to see rude jokes is in an official Latin name.

The snails themselves are the most abundant and widely recognized slipper snails.  They are originally from the east coast of North America.  But they were introduced into England in the late 19^th century and are now also widely distributed in Europe.  Like all calyptraeids they change sex from male to female.  One unusual thing about Crepidula fornicata is that the animals often stack up one on top of the other. The males, which are smaller, sit on the backs of the females (can you see where this is going?). 

Clusters of Crepidula fornicata attached to a clam shell.

So how does this relate to the name Crepidula fornicata? 

The genus name, Crepidula, is straightforward Latin and refers to a small slipper or sandal.  This name was first applied to slipper shells in 1822 by the great evolutionary biologist and natural historian Jean-Baptiste Lamarck, and has been used every since.   

The species name, fornicata (giggle), which distinguishes this species from other species of Crepidula is even older, and the meaning is not so clear.  Following the system designed by Carl Linnaeus - the originator of the naming system we use today – the species name is usually descriptive.  This helps biologists remember the names of the species:  Crepidula plana is flat; Crucibulum spinosum is spiny; and so forth.

So the serious and rather dry explanation for the name fornicata is that when Linnaeus himself coined the name in 1758 he was referring to the shape of the shell.  Fornicata from the root fornicatus means vaulted or arched. 

Crepidula fornicata "fornicating"

BUT…. Could the name also be a lascivious reference to the animals’ sex lives?

A rude joke would be in character for Linnaeus.  Surprisingly, going against all of our stereotypes of dry old scientists, there are quite a few records of Carl’s sense of humor.  He famously named the blue whale Balaenoptera musculus, which means both “muscular” but also “little mouse".  He pointedly named a useless and obscure weed after one of his critics.  His salty language and focus on the sexual organs of flowers for identification (features that are still useful today), was considered at the time as "too smutty for British ears".  He also named a number of clams and mussels for their resemblance to female genitalia.  Smutty indeed.  And not something most of us would notice when facing a plate of clams with garlic and olive oil.

The original description gives us no clues:  “Oval shell, intact posterior, obliquely curved, concave rear lip.  Habitat to Elba Island.  Differs from the preceding base lateral, white concave shelf.”

I don’t know if the name fornicata reflected Linnaeus’ knowledge of the sex lives of these snails.  It seems unlikely.  At the time samples reaching Europe from the New World were almost exclusively shells.  Sex change in Crepidula was not to be discovered for another 150 years, but perhaps reports of aggregations of small and large animals reached Linnaeus.  Maybe that was all the suggestion he needed.  With his naughty interpretation of so much biology and his propensity to pun, it is quite possible that the name is a clever wordplay on fornicatus meaning arched, and fornicor meaning to fornicate or to prostitute.

Fun Facts About Scientific Names