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A hand holding a small snail hiding in its shell
Information icon The magnificent ramshorn has a coiled shell in the shape of a rams horn, often reaching the size and weight of a dollar coin. The shell is brown colored (often with leopard-like spots) and fragile. Photo by USFWS.

Magnificent ramshorn

Planorbella magnifica

  • Taxon: Gastropod, freshwater snail
  • Range: Lower Cape Fear River Basin, North Carolina
  • Status: Candidate (2011)

This snail is an integral part of a complex food web found in freshwater ponds exclusively along coastal North Carolina. This rare snail can no longer be found in the wild places it once inhabited, and is not to be confused with a common relative (the ramshorn snail) found abundantly in pet shops and aquariums. The magnificent ramshorn was pushed out of its natural habitat and since 1993 remains in existence only in captivity. If enough habitat is secured in suitable ponds and sustained into the future, magnificent ramshorn snails could be released to repopulate their historical habitat.

Appearance

The magnificent ramshorn has a coiled shell in the shape of a ram’s horn. Its brown coiled shell r grows to the size and weight of a U.S. dollar coin, roughly 1.38 inches in diameter and 0.79 inch in height. The width of its shell, in relation to the diameter, makes it easily identifiable at all ages to those familiar with freshwater snails. It’s also distinctive in that its aperture is very large, bell-shaped, and is the widest section of the coil. It also loses its eyesight over time as the eyes become covered by the thickened cuticle. Download a presentation on magnificent ramshorn conservation.

A pinkish red snail with a rounded shell like a rams horn
Magnificent ramshorn adult. Photo by Andy Wood, The Coastal Plains Conservation Group.

Habitat

The snail is adapted to still or slow-flowing aquatic habitats, and lays eggs on spatterdock and lily pads. Salinity and pH appear to have been major factors limiting the distribution of the magnificent ramshorn, as the snail prefers freshwater bodies with pH within the range of 6.8–7.5.

Diet

The magnificent ramshorn snail is an herbivore. It eats submerged aquatic plants, algae, and detritus. In captivity, one of their favorite food items is ripe seed head of spatterdock. They eat various other plants, including lettuce, and algae wafers with spirulina. Juveniles have been observed feeding on detritus and biofilm. Like other snails, it has a radula, sometimes called a “rasping tongue,” that scrapes against the substrate they are crawling across.

Historical range

The magnificent ramshorn is believed to be found only in southeastern North Carolina. The species was historically known from only four sites in the lower Cape Fear River Basin in North Carolina — the snail appears to be extinct at all four sites. Those sites were:

  1. Greenfield Lake, a millpond located on a tributary to the Cape Fear River within the present city limits of Wilmington, New Hanover County
  2. Orton Pond (aka Sprunt’s Pond), a millpond located on Orton Creek in Brunswick County
  3. Sand Hill Creek Pond (aka Pleasant Oaks Pond), a millpond on Sand Hill Creek in Brunswick County.
  4. McKinzie Pond, a millpond on McKinzie Creek, in Brunswick County

Surveys of more than 100 potential sites over the last few decades have not uncovered any additional localities with this snail. Although the complete historical range of the species is unknown, its size and the fact that it was not reported until 1903 suggest that the species may have always been rare and localized.

Current Range

Believed to be extirpated from the wild. The last individual seen in the wild was in 2004-2005.

An outstretched hand holding a dozen or more snails
Magnificent ramshorn specimens. Photo by USFWS.

Partnerships, Research and Projects

The U.S. Fish and Wildlife Service works with others to implement conservation. Three organizations maintain a captive population of the species to ensure its survival and produce individuals for future reintroductions. Known surviving individuals of the species are held and propagated by the following organizations:

  • North Carolina Wildlife Resources Commission’s Watha State Fish Hatchery currently has thousands of snails in captivity.
  • Coastal Plain Conservation Group (CPCG) provides ecosystem research, conservation education, and habitat management.
  • North Carolina State University’s Veterinary School.

In captivity, the magnificent ramshorn snail is thriving by the thousands. Finding the high-quality and salt-free habitat it needs is a priority to securing its future. A team of experts led by the North Carolina Wildlife Resources Commission is evaluating the reintroduction potential of several sites.

The next step is recruiting private landowners in the Wilmington area who are willing to carry out conservation actions to benefit the snail. During the summer of 2018, Service biologists conducted field surveys to identify presence of spatterdock and lily pads, general site conditions and pH levels.

Timeline

  • 1992, collected 150 individuals, propagated thousands. All current animals are descendants of the original population.
  • 1996, lost all but 12 to Hurricane Fran.
  • 2004, found 28 individuals.
  • 2007, new found individuals introduced to captive population.
  • 2012, the magnificent ramshorn was added to the list of candidate species for Endangered Species Act protection.
  • 2016, North Carolina State University Veterinary School started holding a group of magnificent ramshorn snails.
  • 2018, North Carolina Wildlife Resources Commission re-established a captive population.
  • 2019, the Service conducting a species status assessment.

How you can help

Landowners in a few areas within (or with similar characteristics to) the historic range can shore up dams that protect ponds, providing safe homes for the snails and other valued species, and preserving the scenic appeal of cypress trees and water lilies that share their need for freshwater. Finding enough suitable ponds for the snails in the lower Cape Fear River basin is an urgent need. Biologists are optimistic that Endangered Species Act protection will not be necessary to ensure the species’ survival if enough suitable ponds are made available to the species and sustained into the future.

Subject matter experts

Conservation challenges

The threats are high in magnitude and ongoing: saltwater intrusion and other water-quality degradation, nuisance-aquatic-plant control, storms, and sea-level rise. Efforts have been made to restore habitat for the magnificent ramshorn at Greenfield Lake, one of the sites known to have supported the species. All of the sites continue to be affected or threatened by the same factors believed to have resulted in extinction of the species from the wild. The Greenfield Lake population was perhaps affected by breaks in sewer lines on the bottom of the lake, sewage overflow, lake drawdowns, and chemical weed management. The Sand Hill Creek population of the magnificent ramshorn is believed to have disappeared in 1996 when the dam on the pond was breached during flooding associated with Hurricane Fran. Development, bacterial infections, and predation by frog tadpoles challenge the ramshorn snail’s chances of succeeding in the wild at any location. The snail disappeared from the Cape Fear area after the river was dredged to make passage for big ships; dredging caused saltwater to make its way further up-river where the snails lived and salty river water overtopping the dams of ponds during high flow events is a concern.

Federal Register notices

The following Federal Register documents were automatically gathered by searching the Federal Register official API with this species’ scientific name ordered by relevance. You can conduct your own search on the Federal Register website.

  • We're sorry but an error occurred. Visit the Federal Register to conduct your own search.

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