Partridge Tun Shell, commonly known as the Partridge Tun or Cask Shell
Phylum: Mollusca, Class: Gastropoda, Order: Littorinimorpha, Family: Tonnidae, Genus: Tonna, Species: T. perdix · Tonnidae (Tun or Cask shell family) · Gastropod, whole shell, oval to rounded globular shape with a very large body whorl and small spire
Species
Tonna perdix
Shell Type
Gastropod, whole shell, oval to rounded globular shape with a very large body whorl and small spire
Family
Tonnidae (Tun or Cask shell family)
Size
Approximately 4 to 5 inches, which is standard for a mature adult specimen. Adults of this species typically range from 3 to 7 inches in length.
Color & Pattern
The shell features a warm, creamy-white or light tan base color overlaid with characteristic vertical rows of small, square or rectangular reddish-brown and white spots, resembling the plumage of a game bird (partridge). The pattern is naturally vibrant with a glossy smooth finish.
Rarity
Common in its native Indo-Pacific range, though beach-worn specimens are found more frequently than pristine live-collected ones.
Habitat
Inhabits shallow subtidal waters, typically found buried in sand or crawling across sandy flats, coral rubble, and seagrass beds from the intertidal zone down to depths of about 30 meters.
Geographic Range
Widespread throughout the Indo-Pacific region, spanning from the Red Sea and East Africa across the Indian Ocean to Polynesia, Hawaii, and Australia.
Description
An exceptionally lightweight yet large shell possessing a thin, fragile structure dominated by an inflated, voluminous body whorl and a remarkably reduced spire. The surface is distinctly sculptured with low, rounded spiral cords and shallow grooves. The aperture is very wide and ovate, ending in a short anterior canal with a simple, thin outer lip.
Key Features
Characterized by its lightweight, inflated globular shape, large body whorl, virtually flat or very low spire, lack of an operculum in adults, and the distinct pattern of alternating white and brownish spots arranged in check-like rows.
Collector Value
Moderately sought after by global shell collectors due to its attractive pattern and large size. Specimen value typically ranges from $10 to $30 depending on exact size, locality data, and perfection of the lip.
Condition Notes
The specimen appears to be in good to fine collector condition with intact structure, minimal wear on the apex, and well-preserved natural coloration and pattern, graded as Fine.
Interesting Facts
Tun shells are specialized predators that feed primarily on echinoderms, especially sea urchins and sea cucumbers. They secrete a specialized saliva containing sulfuric acid to paralyze and digest their prey's soft tissues.
Ecological Role
Acts as an important carnivorous predator controlling sea urchin and echinoderm populations within tropical reef and sandflat ecosystems. Not currently listed as endangered or heavily regulated.
Similar Species
Tonna olearium (Giant Tun) and Tonna galea (Giant Tun), which are generally much larger, heavier, and feature different proportional spiral ribbing.
Beach Finding Tips
Best found by snorkeling or scuba diving in shallow sandy areas near coral reefs at night, when the living snails emerge from the sand to hunt. Beach drift finds are usually heavily water-worn.