Spotted trunkfish

Lore & Background

The spotted trunkfish was first formally described as Ostracion bicaudalis in 1758 by Carl Linnaeus in the 10th edition of Systema Naturae with its type locality given as 'India'. The 5th edition of Fishes of the World classifies the genus Lactophrys within the family Ostraciidae in the suborder Ostracioidea within the order Tetraodontiformes. The genus name Lactophrys is a compound of lactaria, meaning a 'milkcow', and ophrys, meaning 'eyebrow', a reference to the spines above the eyes resembling the horns of a cow. The specific name, bicaudalis, means 'two tailed', a reference to the two spines 'below the tail', a mystery because this fish does not have any spines under its tail but there are two spines on either side of the anal fin.

Members of this family are known as boxfishes because they have a hard outer covering consisting of hexagonal plate-like scales fused together into a solid, triangular or box-like carapace. The eyes, snout, fins and tail protrude from this. The spotted trunkfish is basically white or yellowish with a regular pattern of numerous black spots on the body and tailfin. Just behind the eye, adult fish have a diagonal row of three white spots where black ones would have been expected. The snout is plain white, with no spines above the eye and a pair of sharp spines in front of the anal fin.

The spotted trunkfish is found in the Caribbean Sea, the southern half of the Gulf of Mexico, Ascension Island and the northeastern coast of South America as far east as Brazil. It prefers clear water and is usually associated with coral reefs with fissures, holes and overhangs, at depths down to about 30 m (100 ft).

Reader's Guide

The spotted trunkfish is notable for its distinctive hard, box-like carapace formed from fused hexagonal scales, which limits its movement to slow rippling of its dorsal and anal fins and gentle beating of its pectoral fins, with the tail fin used only when faster motion is required. It is a benthic species, feeding on or near the seabed on a diet that includes crabs, shrimps, molluscs, sea urchins, starfish, brittle stars, sea cucumbers, tunicates and seagrasses. Like all trunkfish of the genus Lactophrys, it secretes a colorless toxin from glands on its skin when touched; the toxin is only dangerous when ingested, so there is no immediate harm to divers, but predators as large as nurse sharks can die from eating a trunkfish. Its colloquial names in Caribbean countries—boxfish, cow-fish or shellfish—reflect its appearance and local recognition. The species was first described by Carl Linnaeus in 1758, though its type locality was given as 'India', which is not its actual range. The specific name bicaudalis ('two tailed') is noted as a mystery because the fish has no spines under its tail, but rather two spines on either side of the anal fin.

Did You Know?

• The spotted trunkfish secretes a colorless toxin from glands on its skin when touched, which can kill predators as large as nurse sharks if ingested.
• Its specific name bicaudalis means 'two tailed', but the fish has no spines under its tail—only two spines on either side of the anal fin.
• Adult spotted trunkfish have a diagonal row of three white spots just behind the eye, where black spots would be expected.
• The genus name Lactophrys combines words meaning 'milkcow' and 'eyebrow', referring to spines above the eyes resembling cow horns.