Dromedary jumping-slug (Hemphillia dromedarius)

Also known as: dromedary jumping slug
KingdomAnimalia
PhylumMollusca
ClassGastropoda
OrderStylommatophora
FamilyArionidae
GenusHemphillia (1)
SizeLength: 3 - 6 cm (2)
Top facts

The dromedary jumping-slug has yet to be classified by the IUCN.

The dromedary jumping-slug (Hemphillia dromedarius) is a relatively large slug species with a distinctive appearance. This rather poorly known but intriguing mollusc has a pronounced hump on its back, which contains its internal organs as well as a small internal shell that is partially visible through a slit in the skin (2) (3) (4) (5). The tail of the dromedary jumping-slug is flattened from side to side, and has a small horn at the tip (2) (3) (4).

The common name of the dromedary jumping-slug comes from its remarkable escape behaviour. When disturbed, this species violently writhes its body from side to side, presumably to distract or escape from potential predators (4) (5) (6). This behaviour may also cause the slug to lose its grip on a log or bark, allowing it to tumble away from danger (5).

The body of the dromedary jumping-slug is mainly grey, with cream-coloured mottling on the sides. The underside of this species varies from pale yellow to bright orange-yellow or cream (2) (3) (4).

The dromedary jumping-slug is found only in western North America, where its range extends from Vancouver Island in British Columbia, Canada, to the Cascade Mountains and Olympic Peninsula in Washington, in the United States (3) (4) (6). There is also a record of this species from northwest Oregon, but its presence there has not yet been confirmed (4) (6).

In British Columbia, the dromedary jumping-slug is known only from a few locations on southern Vancouver Island (3) (6), although much of the potential habitat in the region has not yet been surveyed for this species (6).

The exact habitat requirements of the dromedary jumping-slug are not well known, but this species is thought to be dependent on mature, old-growth coniferous forests (2) (4) (6), and occurs at elevations up to about 1,436 metres (4). At several high-elevation locations in Washington, this unusual slug has also been found on talus slopes in sparsely forested, subalpine habitats (4).

The dromedary jumping-slug requires areas that are continually moist, as well as areas with abundant coarse, woody debris, including decaying logs, in which it can take refuge and lay its eggs (3) (4) (6).

Very little is currently known about the biology and breeding behaviour of the dromedary jumping-slug. This species is believed to be herbivorous, but in captivity it does not readily eat plant matter, suggesting that it may perhaps instead feed on fungi, lichens or other material in the wild (2) (4) (6).

The dromedary jumping-slug is a hermaphrodite, meaning that it possesses both male and female reproductive organs (2) (3) (4) (6). Individuals typically lay clutches of 50 to 60 eggs, depositing them on moist, decaying logs (3) (4) (6). The eggs are usually greyish or semi-opaque (4) (6). This species may potentially take two years to reach maturity (6).

Dromedary jumping-slugs are mostly active at night (6), and are vulnerable to a range of predators, including small mammals, birds, beetles and carnivorous snails (3) (4).

Relatively little is currently known about the dromedary jumping-slug’s population size, but this species is generally recorded at low densities. The main threat to this distinctive slug is likely to be the loss, fragmentation and degradation of its forest habitat, mainly due to logging and urbanisation. The dromedary jumping-slug is not thought to be good at dispersing to new areas, meaning that its populations can easily become isolated (3) (4) (6).

Other potential threats to this slug include predation or competition from introduced species such as snails, or changes to its habitat as a result of invasive plants (3) (4) (6). Inappropriate forest management techniques, such as the removal of logs or crushing of vegetation by machinery, may also negatively impact upon the dromedary jumping-slug. In addition, any changes to the forest habitat that reduce moisture levels or remove woody debris will make areas unsuitable for this species (6).

In Canada, the dromedary jumping-slug is listed as ‘Threatened’ by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC), which determines the status of species that are considered to be at risk in the country (4) (7). It is also protected under the Species at Risk Act (SARA), which provides it with legal protection and aims to secure necessary actions for its recovery. In addition, the dromedary jumping-slug receives protection under the Canada National Parks Act where it occurs within the Pacific Rim National Park Reserve (3). In the United States, the dromedary jumping-slug currently receives no special legal status (4).

A recovery strategy published for the dromedary jumping-slug includes objectives such as protecting the areas where the species occurs, identifying and tackling the threats it faces, and undertaking research to find out more about its biology and habitat needs (6). It will also be important to clarify the extent of its distribution (2) (8) and to ensure that key habitat features, such as decaying logs, are maintained within forests (8).

Its strange appearance and bizarre escape behaviour make the dromedary jumping-slug a potentially useful flagship species for the conservation of old-growth forest habitats and the invertebrate communities that inhabit them (4). This slug is also likely to be an important component of its ecosystem, helping to decompose and recycle organic material on the forest floor, and providing food for other animals (6). Public education programmes are helping to raise awareness of this and other terrestrial invertebrates in British Columbia (3), and research on the dromedary jumping-slug and its habitat may also benefit other slug species that are at risk (6).

Find out more about the dromedary jumping-slug:

More information on invertebrate conservation:

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
arkive@wildscreen.org.uk

  1. Integrated Taxonomic Information System (ITIS) (August, 2013)
    http://www.itis.gov/
  2. NatureServe Explorer - Hemphillia dromedarius (August, 2013)
    http://www.natureserve.org/explorer/index.htm
  3. Government of Canada: Species at Risk Public Registry - Dromedary jumping-slug (August, 2013)
    http://www.sararegistry.gc.ca/species/speciesDetails_e.cfm?sid=765
  4. COSEWIC (2003) COSEWIC Assessment and Status Report on the Dromedary Jumping-slug Hemphillia dromedarius in Canada. Committee on the Status of Endangered Wildlife in Canada, Ottawa. Available at:
    http://publications.gc.ca/collections/Collection/CW69-14-319-2003E.pdf
  5. The Nature Conservancy - The secret lives of jumping slugs (August, 2013)
    http://www.nature.org/ourinitiatives/regions/northamerica/unitedstates/washington/explore/the-secret-lives-of-jumping-slugs.xml
  6. British Columbia Invertebrates Recovery Team (2008) Recovery Strategy for Dromedary Jumping-slug (Hemphillia dromedarius) in British Columbia. Preparted for the B.C. Ministry of Environment, Victoria, British Columbia. Available at:
    http://www.env.gov.bc.ca/wld/documents/recovery/rcvrystrat/dromedary_jumping-slug_rcvry_strat_2008.pdf
  7. Committee on the Status of Endangered Wildlife in Canada (COSEWIC) - Dromedary jumping-slug (August, 2013)
    http://www.cosewic.gc.ca/
  8. Ovaska, K. and Sopuck, L. (2004) Recovery of Terrestrial Gastropods in British Columbia. Proceedings of the Species at Risk 2004 Pathways to Recovery Conference, March 2-6, 2004, Victoria, British Columbia.