Kanab ambersnail

Kanab ambersnail
A Kanab ambersnail at Vasey's Paradise in Grand Canyon National Park.
Scientific classification
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
(unranked): clade Heterobranchia

clade Euthyneura
clade Panpulmonata
clade Eupulmonata
clade Stylommatophora
clade Elasmognatha

Superfamily: Succineoidea
Family: Succineidae
Subfamily: Succineinae
Genus: Oxyloma
Species: Oxyloma haydeni
Subspecies: O. h. kanabense
Trinomial name
Oxyloma haydeni kanabense
Pilsbry, 1948[2]
Habitat of the Kanab ambersnail
(marked in orange)
Synonyms

Oxyloma kanabense Pilsbry, 1948

The Kanab ambersnail, scientific name Oxyloma haydeni kanabense or Oxyloma kanabense, is a critically endangered subspecies or species of small, air-breathing land snail, a terrestrial pulmonate gastropod mollusc in the family Succineidae, the amber snails. The common name of the amber snails is based on the shell, which is translucent and when empty usually resembles amber in color.[3]

This species is endemic to the United States, specifically the state of Arizona and Utah, where it was first collected in the early 20th century. It has been listed as endangered on the United States Fish and Wildlife Service list of endangered species since 8 August 1991.

This snail lives in wetlands, springs, and seeps,[4] and only two of its natural habitats are known to exist: Three Lakes, a meadow near Kanab, Utah, and Vasey's Paradise, a spring along the Colorado River within Grand Canyon National Park.[4] In its natural habitat it is rather polyphagous, feeding mainly on bacteria, plants and fungi, and reproduces during the summer.

Now considered a Critically Endangered species on the IUCN Red List of Threatened Species[1] due to a series of factors (including anthropic influence[5]), the Kanab ambersnail has been reintroduced to three springs above the historic high water level along the Colorado River.

Taxonomy

An Ambersnail crawls across a hand, next to a U.S. dime (18 mm / 0.7 in diameter).

Specimens of the Kanab ambersnail were first collected in 1909 by James Ferriss from: "The Greens", 10 kilometers (6.2 mi) above Kanab, Utah on Kanab Wash, on a wet ledge among moss and Cypripediums.[6] These specimens were originally thought to belong to the species Succinea hawkinsi.[6][7]

Pilsbry (1948)[2] transferred these specimens to the genus Oxyloma and erected the subspecies kanabensis in the species haydeni for them. Arthur Clarke (1991) notes that Pilsbry’s decision to accord the Kanab ambersnail subspecific status was preliminary, and that, as Pilsbry himself noted, “its taxonomic status should be reevaluated.”

Clarke (1991)[8] and Shei K. Wu (Colorado Museum of Natural History, Boulder, Colorado, pers. comm. 1992, 1995)[7] suggest that the Kanab ambersnail may deserve full species status. Earle Spamer (Academy of Natural Sciences of Philadelphia, Philadelphia, Pennsylvania, pers. comm. 1994)[7] stated that although current published mollusk checklists (Turgeon et al. 1988 and Groombridge 1993) treat the Kanab ambersnail at species level rather that as a subspecies, nonetheless, until the criteria are derived (and published) by which the taxon can be known to be a separate species, it should continue to be called by its original name, the one published by Pilsbry (1948): Oxyloma haydeni spp. kanabensis.[7] Despite this, NatureServe does list this taxon as a species.[9]

Description

The Kanab ambersnail is a terrestrial snail in the family Succineidae. The empty shell is a light amber color. The live snail has a mottled grayish-amber to yellowish-amber colored shell. The shell is dextral (right-handed spiral), thin-walled, with an elevated spire and a Daly, patulous (expanded) aperture. Fully mature individuals are about 14 to 19 mm (0.5 to 0.75 inch) long, 7 to 9 mm (0.25 to 0.33 inch) in diameter, with 3.25 to 3.75 whorls in a drawn out spire.[7]

Its eyes are borne at the ends of long peduncles (stalks), while the tentacles are reduced to small protuberances at the base of the eye stalks.[7]

Ecology

The natural predators of this snail are passerines, the (American robin),[7] and deer mice.[10]

Vasey's Paradise, one of the two natural habitats of the Kanab ambersnail.

Habitat

In 1996, 16% of the Ambersnail's habitat at Vasey's Paradise was destroyed in a flood, and a more disastrous previous flood in 1994 had probably already threatened the snail's habitat.[11] The suitable area for habitat in Three Lakes is believed to extend to an area 1.3 km long, and 90 m wide, and genetic diversity seems to indicate that the area is more stable than Vasey's Paradise. However their redistribution is also affected by the presence of their host plants and rock ledges.[12]

Three Lakes, a privately owned wet meadow near Kanab, is one of only two natural habitats for the Kanab Ambersnail. The snail's habitat is threatened by commercial development by the owner of Three Lakes.

Despite being air-breathing molluscs, they can survive for up to 32 hours in cold, highly oxygenated water, which may have helped to disperse its population around the Colorado Valley area since a controlled release was conducted in 1998.[4]

Feeding habits

The Kanab ambersnail is typically found on host plants, primarily the scarlet monkeyflower and watercress,[13] but also sedges and rushes. It feeds on plant tissue, fungi, algae, and bacteria, using its radula to scrape off food.[14]

Life cycle

Like all pulmonate land snails, ambersnails are hermaphroditic, having both male and female reproductive systems, and are believed to be capable of self-fertilization. In the wild they live for between 12 and 15 months. Young snails enter dormancy between October and November, becoming active again in March and April. Mature snails reproduce in the summer months.[4]

Population

Only two wild populations of the snail are known to exist,[3] specifically, Three Lakes near Kanab, Utah and Vasey's Paradise.[11] The latter was not discovered until 1991 when a survey of mollusks in the area was conducted.[12] There was formerly a third population present in Kanab, Utah, but it is believed to have become extirpated through the destruction of its habitat.[15]

Conservation

The Kanab ambersnail was proposed for emergency listing in 1991, and the United States Fish and Wildlife Service (USFWS) has listed the Kanab ambersnail as endangered since 1992.

The Kanab ambersnail is evaluated as Critically Endangered on the IUCN Red List of Threatened Species.[1]

In Utah, its habitat was threatened by commercial development,[5] whereas the Grand Canyon population is threatened by discharges from the Glen Canyon Dam which can sweep the snail and its habitat downstream.

Reintroduction releases have been conducted at three sites along the Colorado river, each releasing 150 snails.[4] The first of these releases was conducted in September 1998, and all sites were sufficiently high enough to not be flooded by normal dam activity. A second release was conducted at the same three sites in July 1999 to boost population densities and improve genetic variability, but only one of the three sites, Upper Elves Chasm, has established a new population.[4]

References

This article incorporates public domain text (a public domain work of the United States Government) from the reference.[7]

  1. 1 2 3 Roth, B (1996). "Oxyloma kanabense". IUCN Red List of Threatened Species. Version 2006. International Union for Conservation of Nature. Retrieved 26 November 2006.
  2. 1 2 Pilsbry H.A. 1948. Land Mollusca of North America. The Academy of Natural Science of Philadelphia Monographs. Vol. II (Part 2): 797-798.
  3. 1 2 "Mollusks". Grand Canyon National Park. Retrieved 2006-11-25.
  4. 1 2 3 4 5 6 Jeff Sorensen. "Kanab Ambersnail (Oxyloma haydeni kanabensis)". gf.state.az.us. Retrieved 2006-11-26.
  5. 1 2 Randall Fitzgerald, Mugged by the State: Outrageous Government Assaults on Ordinary People and their Property, Regnery Publishing, Inc. (2003) ISBN 0-89526-102-2
  6. 1 2 Ferriss, J. H. (1910). "A collecting excursion north of the Grand Canyon of the Colorado". The Nautilus. 23: 109–112.
  7. 1 2 3 4 5 6 7 8 U.S. Fish and Wildlife Service. 1995. Kanab Ambersnail (Oxyloma haydeni kanabensis) recovery plan. U.S. Fish and Wildlife Service, Denver, Colorado. 21 pp. online http://ecos.fws.gov/docs/recovery_plan/951012.pdf
  8. ↑ Clarke, A.H. 1991. Status survey of selected land and freshwater gastropods in Utah. Unpublished report prepared for the U.S. Fish and Wildlife Service, Denver, Colorado. 70 pp + cxii.
  9. ↑ Oxyloma kanabense. NatureServe, accessed 19 August 2009.
  10. ↑ Stevens, L.E., V.J. Meretsky, D.M. Kubly, J.C. Nagy, C. Nelson, J.R. Petterson, F.R. Protiva, and J.A. Sorensen. 1997b. The impacts of an experimental flood from Glen Canyon Dam on the endangered Kanab Ambersnail at Vaseys Paradise, Grand Canyon, Arizona: Final Report. Grand Canyon Monitoring and Research Center, Flagstaff.
  11. 1 2 Miller, Mark P.; Stevens, Larry P.; Busch, Joseph D.; Sorensen, Jeff A.; Keim, Paul. Amplified fragment length polymorphism and mitochondrial sequence data detect genetic differentiation in endangered southwestern U.S.A. ambersnails (Oxyloma epp.)
  12. 1 2 Brown, Steve; Cherlow, Jay R (2004). Bureau Of Reclamation: An Assessment of the Environmental Impact Statement on the Operations of the Glen Canyon Dam. DIANE Publishing. pp. 77–8. ISBN 0-7881-4057-4.
  13. ↑ Stevens, Lawrence E. (2001). "Planned Flooding and Colorado River Riparian Trade-Offs Downstream from Glen Canyon Dam, Arizona". Ecological Applications: 705. doi:10.1890/1051-0761(2001)011[0701:pfacrr]2.0.co;2.
  14. ↑ Bill Vercammen. "Success at snail's pace: KAS recovery update". desertusa.com. Retrieved 2006-11-27.
  15. ↑ Clarke, A.H. 1991. Status survey of selected land and freshwater gastropods in Utah.
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