Tonna Canaliculata, Canaliculate Tun Shell
Phylum: Mollusca, Class: Gastropoda, Order: Littorinimorpha, Family: Tonnidae, Genus: Tonna, Species: canaliculata · Tonnidae (Tun Shells) · Gastropod (Univalve); Globular spiral shape
Species
Tonna canaliculata
Shell Type
Gastropod (Univalve); Globular spiral shape
Family
Tonnidae (Tun Shells)
Size
3 to 4 inches (75-100mm); typical adult range is 2 to 6 inches.
Color & Pattern
Creamy white to light beige base with faint yellowish bands. The sculpture consists of deep, wide spiral grooves (costae) separated by prominent ridges. The protoconch (tip) is a darker brownish-gold.
Rarity
Common; frequently found in commercial shell trades but less common to find in perfect condition on beaches due to its thin, fragile structure.
Habitat
Found in warm, tropical marine waters. Sand or mud substrates in subtidal depths from 10 to 100 meters.
Geographic Range
Indo-West Pacific region, ranging from the Red Sea and East Africa to Australia and Japan.
Description
A lightweight, thin-walled, globular shell known for its 'inflated' appearance. It features a moderately low spire and a very large body whorl. The surface is characterized by strong, flattened spiral ribs separated by narrow, deep channels (sulci).
Key Features
Deeply channeled sutures and broad, flat spiral ribs. The thin, almost translucent shell wall and the lack of an operculum in adult specimens are diagnostic of the Tonna genus.
Collector Value
Modest ($5 - $15 USD). It is a decorative staple in many collections. Large, exceptionally thin specimens with deep coloration are more highly prized.
Condition Notes
Good condition. The protoconch is intact and the spiral ridges show minimal erosion. Some slight beach-wear on the outer lip is visible. Typical 'Fine' grade for a collector.
Interesting Facts
Tun shells are specialized hunters that feed on sea cucumbers. They use a highly acidic saliva (containing sulfuric acid) to soften the skin of their prey before consuming them with a long proboscis.
Ecological Role
Active predator of echinoderms. They help regulate sea cucumber populations in tropical reef ecosystems. Not currently listed as endangered.
Similar Species
Tonna galea (Giant Tun) which is much larger and thicker-shelled; Tonna perdix (Pacific Partridge Tun) which has a mottled brown animal-print pattern.
Beach Finding Tips
Look for them after heavy storms or monsoons which wash these lightweight shells from deeper sandy beds onto the shore. Check the high-tide line near beach debris.