Meet the Cave Shrimp: 2025 USA Cave Animal of the Year
The USA Cave Animal of the Year program enters its sixth year in 2025. This program highlights fragile animals in caves and associated subterranean habitats in the US. You can learn about these animals in our web pages at https://caves.org/conservation/ and get to know the fascinating occupants of our favorite domain a little better while enjoying caves and karst. Remember, we are merely visitors, so tread lightly, leave nothing but footprints and only take photos. What animal is the focus for 2025?
USA Cave Animal of the Year in 2025: Cave Shrimp
Endemic cave shrimp are shrouded in mystery and karst and have invertebrate charisma all their own. These small, translucent creatures are rare but are being discovered more often as we push our boundaries in exploration and clean up our waters. They are still shy, but grab some popcorn or snorkeling gear and join us as we become better acquainted!
What Does a Cave Shrimp Look Like and Where Do They Live?
There are only nine described cave shrimp species known in the US belonging to the families Atyidae, Palaemonidae, and Procarididae. Many cave shrimp species are small, eyeless scavengers living in rivers and pools in cave systems or deeper groundwater aquifers of Alabama, Florida, Kentucky, and Texas, while others are known from anchialine pools of Hawaii.
What Do Cave Shrimp Eat?
The diet of a typical cave shrimp consists of microorganisms, plant detritus and other invertebrates. Most of their life history is a mystery, but we expect that with austere conditions, cave shrimp generally grow slowly. They likely have long periods between broods with a low reproductive success rate from eggs and larvae to adults. There may yet be more undiscovered species lurking in the dark, living happy little lives in happy little karst areas, including at least one undescribed species in Alabama. Most species of cave shrimp have very restricted ranges and, in some cases, are known from only a single cave system.
Threats to the Cave Shrimp
These organisms are typically highly susceptible to environmental change and water quality. Five species are listed as threatened and endangered currently under the US Endangered Species Act, including the Kentucky Cave Shrimp Palaemonias ganteri (Fig. 1), the Alabama Cave Shrimp Palaemonias alabamae (Fig. 2), Squirrel Chimney Cave Shrimp Palaemon cummingi, Feathered Hawaiian Pool Shrimp Procaris hawaiana and Subterranean Giant Pool Shrimp (Vetericaris chaceorum). Other species, such as the Balcones Cave Shrimp Palaemon antrorum (Fig. 3), are not listed federally but are still of high conservation concern. Cave shrimp are particularly vulnerable to groundwater pollution and habitat destruction. This often means not only protecting the species but also the entire cave ecosystem and keeping surface and subsurface water sources clean of contaminants.
Let’s learn a little bit more about some of the main characters in this story:
Kentucky Cave Shrimp (FIG. 1)
- Scientific name: Palaemonias ganteri
- Appearance: Transparent, about 32 mm (1.25 in) long
- Habitat: Found in Mammoth Cave, Kentucky
- Discovery: First collected in the 1880s in Mammoth Cave
- Conservation status: Endangered on the Endangered Species Act in 1983
Kentucky Cave Shrimp were first discovered in the 1880s and later described in 1901 by W.P. Hay (NPS 2021). They are only known from the lowest levels of cave passage in Mammoth Cave National Park (NPS 2021). They can be difficult to find swimming in the dark recesses of 10 basins, eight of which are in the national park, while two are upstream (NPS 2021). From the 1950s into the early 1970s, they were thought to be extinct. However, after the Clean Water Act of 1972 started to help improve the water quality of our streams, three specimens were observed in 1979 (Stevens 2017). Today, populations are estimated to have bounced back into the thousands, and they are still federally protected.
Alabama Cave Shrimp (FIG. 2 & FIG. 4)
- Scientific name: Palaemonias alabamae
- Appearance: Colorless and transparent, up to 30 mm (1.2 in) long
- Habitat: Found in a few cave systems in Madison and Jackson counties, Alabama
- Discovery: First found at Shelta Cave in 1958, now one of 23 NSS Nature Preserves
- Conservation status: Endangered on the Endangered Species Act in 1988
Balcones Cave Shrimp or Texas Cave Shrimp (FIG. 3)
- Scientific name: Palaemonetes antrorum
- Appearance: Translucent, small
- Habitat: Edwards Aquifer of Texas
- Discovery: From the Artesian Well at San Marcos in the spring of 1896
- Conservation Status: Not listed under the Endangered Species Act but ranked as Endangered on the IUCN Red List
This shrimp is wider-ranging and relatively common in the Edwards Aquifer (Reddell 1994), where they likely feed on microbial biofilms (Hutchins et al. 2016). It appears to retain marine characteristics rather than the morphology seen in freshwater shrimp within the same genus, probably due to the unusual conditions of living in an aquifer (Collins 1998).
How Can You Can Participate?
We need your help spreading the word about Cave Animal of the Year. Please share this website address with friends and on your Grotto social media. If you are lucky enough to find a Northern Cavefish or one of its relatives while caving, help others see it and learn about these cave species. We invite you to take a photo of the cavefish and post it on the USA Cave Animal of the Year Facebook page. In addition, we encourage cavers to report sightings of cavefishes to state biologists that are tracking and studying these species. Have another great year of learning about and helping to conserve habitat for the fascinating animals that make caves their homes! The next time you enjoy the crisp and thrilling waters of the deep cave riverine systems, keep your eyes peeled for itsy-bitsy translucent friends. Maybe we can add another species to the list of our mysterious pals skimming along in the dark. Happy Cavin’!
Dedication to Dr. William D. Pearson
This installment of the Cave Animal of the Year is dedicated to the memory of Dr. William D. Pearson, who passed away in December 2023. Bill was a Professor of Biology at the University of Louisville for 39 years where he taught classes on Ecology, Ichthyology, Fisheries Management, and Biospeleology and mentored 28 graduate students. He and his students surveyed cave aquatic biota including Northern Cavefish. They also developed a cave Index of Biological Integrity. Bill was an excellent scientist, a generous colleague and a caring, affable person. He is missed.
Previous USA Cave Animal of the Year
This is the sixth year for the USA Cave Animal of the Year. The NSS supports this worldwide initiative to bring more attention to the amazing creatures that live underground.
Learn about:
2023 Ceuthophilus Cave Crickets
2021Pseudanothalmus Cave Beetles
2020 Great Basin Cave Pseudoscorpion
Cave Animals of the Year from Other Countries
Several other countries also celebrate Cave Animal of the Year
Germany Triphosa dubitata (Lepidoptera, Moth)
Italy Triphosa dubitata (Lepidoptera, Moth)
Brazil: Hypena spp. (Lepidoptera, Moth)
Switzerland: Triphosa dubitata (Lepidoptera, Moth)
France: Triphosa dubitata (Lepidoptera, Moth)
Greece: Niphargus spp. – Stygobitic freshwater amphipod species
USA Cave Animal of the Year Committee
Don Arburn, Gretchen Baker, Dante Fenolio, Kurt L. Helf, Devra Heyer, Jean Krejca, Cait McCann Terán, Shiloh McCollum, Matthew Niemiller, Kara Posso, and Michael Slay.
