How to Identify Thornback boxfish

To identify Thornback boxfish (Lactoria fornasini), look at these key features.

Physical Characteristics

Body shape

rounded

Coloration

Highly variable, ranging from yellowish-brown to greenish-brown, often with irregular dark spots or blotches. The ventral surface is typically lighter. Juveniles may exhibit more vibrant patterns.

Scale type

none

Mouth position

terminal

Distinctive features

Rigid, box-like body encased in a bony carapace (carapace is triangular in cross-section), Two prominent, forward-pointing spines above the eyes (supraorbital spines), A single, strong spine projecting backward from the dorsal ridge (dorsal spine), A pair of spines projecting backward from the ventrolateral ridges (ventrolateral spines), Small, puckered mouth, Absence of pelvic fins

Dorsal fin

Small, single dorsal fin located far back on the body, typically with 9 soft rays.

Tail fin

Fan-shaped caudal fin, often with a rounded or slightly truncate margin, used for propulsion.

Pectoral fin

Small, rounded pectoral fins, used for steering and hovering.

Distinctive fins

No pelvic fins. All fins are relatively small and used for precise maneuvering rather than rapid swimming.

Identification Tips

1. 1

   Body Shape and Spines

   The most defining characteristic is the rigid, box-like body with a triangular cross-section and the presence of multiple prominent spines: two supraorbital spines above the eyes, one dorsal spine, and two ventrolateral spines. The number and arrangement of these spines are key.

2. 2

   Coloration and Pattern

   Observe the base color and any spots or blotches. While variable, the general pattern can aid in identification, especially in distinguishing it from other Lactoria species.

3. 3

   Mouth and Fin Placement

   Note the small, terminal mouth and the small, paddle-like fins (dorsal, anal, pectoral, and caudal) that are characteristic of boxfishes, allowing for precise, slow movement.

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