Partridge Tun (Also known as the Striped Tun)
Phylum: Mollusca, Class: Gastropoda, Order: Littorinimorpha, Family: Tonnidae, Genus: Tonna, Species: Tonna dolium · Tonnidae (Tun shell family) · Gastropod (snail/univalve), whole shell, spiral shape
Species
Tudicula spirata or Tonna dolium
Shell Type
Gastropod (snail/univalve), whole shell, spiral shape
Family
Tonnidae (Tun shell family)
Size
Approximately 2 to 3 inches in length, which is slightly smaller than average. Adult Tonna dolium typically range from 2.5 to 5 inches.
Color & Pattern
The base color is a creamy white or light beige, adorned with distinct, evenly spaced reddish-brown or orange-brown spiral bands and vertical ribs. The colors appear natural and vibrant, showing clear contrast along the rounded body whorl.
Rarity
Common
Habitat
Inhabits shallow subtidal waters, typically found on sandy bottoms, sand flats, and coral sand environments from the low tide mark down to depths of about 30 meters.
Geographic Range
Indo-West Pacific region, ranging from East Africa and the Indian Ocean through Southeast Asia, Indonesia (including Maluku), to Northern Australia and the Western Pacific.
Description
A lightweight yet surprisingly large-volumed shell featuring a very inflated body whorl, a short spiky spire, and deep spiral grooves that give it a characteristic ribbed texture. The aperture is wide and expansive with a simple outer lip.
Key Features
Extremely inflated body whorl relative to the small spire, prominent spiral ribs running the length of the shell, and a thin, lightweight shell structure without a true operculum in adults.
Collector Value
Moderately common and affordable. Highly valued for its pleasing rounded shape and distinct banding pattern, making it a staple in decorative collections and shell shops. Typically valued between $5 to $15 depending on exact size and perfection.
Condition Notes
The specimen appears to be in good to fine condition, with intact spiral ribbing, strong natural coloration, and a well-preserved spire tip. Minor natural wear on the apex, graded as Fine collector condition.
Interesting Facts
Tun shells are known to secrete a sulfuric acid-containing mucus from their salivary glands to paralyze their prey, which primarily consists of sea cucumbers and echinoderms.
Ecological Role
Acts as an important carnivorous predator in sandy benthic ecosystems, helping control populations of sea cucumbers and other soft-bodied invertebrates. Empty tun shells frequently serve as mobile homes for large hermit crabs.
Similar Species
Tonna perdix (Partridge Tun), which has a more elongated shape and finer white speckling, and other Tonna species which can be distinguished by rib count and color band intensity.
Beach Finding Tips
Best found by beachcombing after strong storms or heavy onshore winds in tropical regions, or by snorkeling in shallow sandy lagoons and reef flats at low tide.
Notes
Maluku