The male spotted boxfish (top) is blue with orange highlights and white spots along the back, whereas the female (second photo) is a fairly uniform brown with white spots all over. Despite their shape, boxfishes are nimble swimmers boasting a good turn of speed and surprising maneuverability.
I got these photos because the male boxfish came up to check me out a couple of times and the female was unperturbed by my presence as she searched for food on an old pier piling.
The spotted boxfish is the most common boxfish in Hawaii. They really are little boxes with a hard carapace. Only their fins, eyes and mouth move. They can also secrete a toxic slime if they’re bothered.
Surprisingly, given their shape, they’re very good swimmers and can easily outdistance a human. Such is their prowess in this regard that they’ve served as inspiration for submarine and car designs.
On a more basic level, they’re always fun to see in the water, puttering along nimbly, and keeping a good distance ahead of pursuing photographers. The top boxfish is a male and the one below, a female.