#clavagelloidea

As usual I've saved something special for the milestone. Quite likely the weirdest bivalves in the world, and that's a group that includes shipworms and freshwater species that hitch a lift upstream in fish gills.

Originally described as Serpula penis by Linnaeus in 1758. But since Serpula is now a genus of tube worms, it certainly didn't stay there. Exactly whose penis is another question, but I'm sure you could find something similar in the Bad Dragon catalogue.

Another names have included Aquaria radiata, 10 different Aspergillum, three different Brechites, Clepsydra javanica, three Penicillus, and Serpula aquaria. An Aspergillum is a device for sprinkling holy water. One of the definitions of Clepsydra ('water thief') is a hollow brass ball with a long neck and lots of small holes around the bell, that if dipped in water will hold it until you take your thumb off the opening at the end of the neck. The common names also include waterspout shell. So all-in-all it would seem most of the taxonomists were making the same associations, based on the wide end of the shell being covered in dozens of tiny holes.

Most of those generic names are invalid because they'd already been applied to something else. I'm honestly amazed 'Verpa' hadn't already been applied to another animal, and it IS the name of a fungus genus. It means 'erect penis' in vulgar Latin, incidentally. Guess what the fungus looks like.

And they really are bivalves, although there's little evidence of that left in the adult shell.

The Clavagelloidea includes genera that bore into living coral, but Verpa lives in soft sediments, with the wide end buried, and the long tube sticking up into the water. The bivalve's siphons run up the tube, to inhale and exhale water, but they can also use their mantle to pump water out through the small holes at the wide end. This presumably loosens the sand and mud, and helps secure the wide end as an suction anchor. Some have been found with sharp curves and bends in the tube, which probably indicates they got knocked over at some point but survived to keep growing.

Some research suggests that the genera in the Clavagelloidea that currently form the Penicillidae and the Clavagellidae actually evolved seperately, possibly from the Lyonsiidae, but converged on the same bizarre anatomy. Clavagellids first appeared in the Upper Cretaceous, but the Penicillids like Verpa didn't show until the Oligocene at least 40 million years later.

Found off the coast of SE Asia and Australia, but very rare and presumed extinct in some areas since they haven't been seen in 50 years.