How are boxfishes protected by their turtlelike carapace?

Boxfishes (family Ostraciontidae) are protected by a rigid, boxlike carapace that encases most of their body, leaving only their eyes, mouth, fins, and tail exposed. This protective covering is composed of fused, hexagonal bony plates. Depending on the species, the carapace takes on a triangular, square, or pentagonal shape in cross section, providing a sturdy physical barrier against predators.12

In addition to this structural defense, boxfishes possess a chemical deterrent; when captured or handled, they exude a toxic substance that can be lethal to other fishes in their vicinity. These defensive mechanisms are characteristic of many members of the order Tetraodontiformes, which often utilize thick, spiny skins or other specialized protections to survive in their environments.13