USA Cave Animal of the Year

This article was originally published in The Midden – Great Basin National Park: Vol. 20, No. 1, Summer 2020.

This protonymph, or young, Great Basin Caves Pseudoscorpion has a lighter coloring than the adult form.

Photo by David Hunter

by Gretchen Baker, Michael Slay, and Matthew Niemiller, Cave Biologists

When you think of caves, do you think about what lives in them? A worldwide program, Cave Animal of the Year, seeks to help bring appreciation to subterranean creatures. Germany started the program in 2009 with a beautiful website. In 2019, Italy created this wesite and Australia created this website. Now, in 2020, the USA has joined the club.

The USA Cave Animal of the Year for 2020 is the Great Basin Cave Pseudoscorpion (Microcreagris grandis Muchmore). It is a small arachnid in the family Neobisiidae and in the genus Microcreagris. This pseudoscorpion genus includes more than 20 related species, is found throughout the world, and includes both cave and surface species.

The Great Basin Cave Pseudoscorpion has a rather interesting history. The Lehman Caves National Monument Custodian (similar to today’s superintendent), T.O. Thatcher, noted and collected the first specimens in the 1930s. However, it took until the 1960s for the pseudoscorpions from the cave to be identified, when Dr. William Muchmore determined it was a new species and formally named it Microcreagris grandis. Since then, this species has been found in other caves in the Park, including alpine caves. However, it has not been found in caves on other mountain ranges. Pseudoscorpions are small arachnids and are distant relatives of spiders, scorpions, harvestmen, and mites. They resemble scorpions but lack the stinging tail. Consequently, pseudoscorpions are sometimes referred to as false scorpions.

Most species are very small, up to three-tenths of an inch (8 mm), and possess eight legs and large claw-like appendages called pedipalps that they use to grab prey. They eat a variety of insects, including flies, beetles, larvae, and tiny springtails. There are more than 3,500 pseudoscorpion species throughout the world. Although pseudoscorpions may be small to our eyes, they are huge in the cave ecosystem; they are the top invertebrate predator in Park caves.