The UC Museum of Paleontology (UCMP) is home to more than five million invertebrate fossil specimens, a majority of them being marine in origin. While rehousing the US Geological Survey’s Menlo Park collections, I came across specimens of Actinella, a genus of terrestrial gastropod. The earliest known air-breathing gastropods in the fossil record appeared during the Carboniferous Period, Carboniferous being a reference to the abundant coal deposits formed at this time, 359 to 299 million years ago.
The name Actinella was established by the British naturalist Richard Thomas Lowe. While serving as a clergyman in the Madeira Islands a Portuguese archipelago in the North Atlantic Ocean Lowe collected, studied, identified and named many different snail genera and subspecies between the 1830s and 1850s. Lowe’s work is still cited today and used in the identification of Actinella fossils. In 1892, the Scottish malacologist Robert Boog Watson described specimens of Actinella in the Journal of Conchology. Thirty years later, Watson’s work with Actinella was referred to and further expanded upon by then University of Colorado, Boulder, Professor T.D.A. Cockerell in a 1922 edition of the journal Nature.
Terrestrial snails evolved from marine snails, but some modern relatives, such as Ellobium aurismidae, the Midas ear snail, have characteristics of both. Certain parts of the world have terrestrial snails that prefer wet habitats, like Carychium minimum, the herald thorn snail. Other snail species, such as Myosotella myosotis, the mouse ear snail, have adapted to live near water with high salinity.
Studies of living specimens of Actinella and other gastropods continue to generate interesting information. For example, in a 2008 Nature article, UC Berkeley Professor Nipam Patel and UC Berkeley postdoctoral fellow Cristina Grande discovered that snails use the same genes as humans do for right-left determination of internal and external structures. With continuing investigations into gastropods, both extinct and living, marine and terrestrial, fossils from UCMP’s USGS Menlo Park invertebrate collection just might lead to another discovery!
Actinella photo by the UCMP Invertebrate Collection crew. Ellobium photo © 2012 Femorale (CC BY-NC 3.0); image has been modified. Myosotella photo by Malcolm Storey (CC BY-NC-SA 3.0); image has been cropped. Carychium photo by H. Zell (CC BY-SA 3.0); image has been modified.