Image: X-ray of leatherjacket spine

X-ray of leatherjacket spine

An x-ray image of a the dorsal spine of a leatherjacket from the Australian Museum Ichthyology Collection.

James King
© Australian Museum


Many of the triggerfishes (Family Balistidae) and leatherjackets (Family Monacanthidae) have a first dorsal fin spine that can be locked into an erect position.

This is made possible by a ball and socket "trigger-like" mechanism. The base of the second spine slots into a groove in the first spine. The locking mechanism is released when the second spine is depressed.

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Tags fishes, ichthyology, x-ray, leatherjacket, triggerfish, Monacanthidae, Balistidae,