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The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

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Common name: Thrush Cowrie

Synonyms and Other Names: pear-shaped cowrie, Cypraea turdus, Erosaria turdus

Identification: Naria turdus is a marine snail with a flat, ovular shell. While this species does have a spiral, it is not visible from the outside. The aperture, or opening of the shell, is serrated and is located on the underside of the shell. The top of the shell is pale gray in color with a distinct pattern of yellow-brown spots similar to that of a thrush bird (Verdcourt 1954; Oleinik et al. 2023). This characteristic thrush pattern distinguishes N. turdus from native cowries. When alive, N. turdus specimens exhibit papillae protruding from their mantle (Oleinik et al. 2023). Empty shells of this species often appear glossy (Lewis 2007).

Size: Average shell length reaching about 38 mm (1.5 inches)

Native Range: This species is native to the Indian Ocean from along the Eastern coast of Africa to the Eastern coast of India (Oleinik 2023).

Alaska	Hawaii	Puerto Rico & Virgin Islands	Guam Saipan

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Ecology: Naria turdus are known to be herbivorous, feeding primarily on algae and other plant material (Oleinik 2023). Some cowries have been observed to be sponge grazers (Pawlik and Deignan 2015). Like other cowries, N. turdus is nocturnal, and little is known about its ecology. This species has been documented in a wide variety of habitats including reefs and seagrass beds. Naria turdus can be found in depths of up to 45 meters (Oleinik et al. 2023). While exact means of reproduction are unknown, other cowries of this genus lay egg clutches that hatch into free-floating larvae known as veligers (Oleinik 2023). In the Caribbean, empty shells of N. turdus have been found with holes drilled into them, suggesting predation by octopuses (Oleinik 2023).

Means of Introduction: The exact means of introduction of this species to the Americas is unknown. However, the most likely pathway is through shipping ballast water or hull fouling (Oleinik et al. 2023). Naria turdus was introduced to the Mediterranean Sea through the Suez Canal (Galil 2009).

Status: Naria turdus is established in Florida and Puerto Rico (Oleinik et al. 2023).

Impact of Introduction: The impacts of this species are currently unknown. The absence of data does not equate to lack of effects. It does, however, mean that research is required to evaluate effects before conclusions can be made.

Remarks: This species has several synonyms due to slight differences in morphology among populations (MolluscaBase 2025).

References: (click for full references)

Galil, B.S. 2009. Taking stock: inventory of alien species in the Mediterranean. Biological Invasions 11:359–372. https://doi.org/10.1007/s10530-008-9253-y.
Oleinik, A.E. 2023. Introduction of Naria turdus (Lamarck, 1810) (Gastropoda: Cypraeidae) from the western Indian Ocean to the island of Aruba, western Atlantic Ocean. The Nautilus 137(1):24–30.
Oleinik, A.E., J.H. Leal, A. DuPont, and N. Uthairat. 2023. A prediction held true: first record of the non-indigenous thrush cowrie Naria turdus (Lamarck, 1810) (Gastropoda: Cypraeidae) in South Florida. The Nautilus 137(1):31-34.
Pawlik, J.R., and L.K. Deignan. 2015. Cowries graze verongid sponges on Caribbean reefs. Coral Reefs 34:663. https://doi.org/10.1007/s00338-015-1279-x.
Verdcourt, N. 1954. The Cowries of the East African Coast (Kenya, Tanganyika, Zanzibar and Pemba). Journal of the East African Society of Natural History 22:129–147.

Other Resources:
Lewis, E.R. 2007. Cowries- Maui Shells. https://people.eecs.berkeley.edu/~lewis/cowries.html.
MolluscaBase eds. 2025. MolluscaBase. Naria turdus (Lamarck, 1810). Accessed through: World Register of Marine Species at: https://www.marinespecies.org/aphia.php?p=taxdetails&id=1079151 on 2025-08-22.

Author: Stratton, L.D.

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.