The shame-faced crab (aka box crab) gets its name from the
way its claws (or chelae) cover its face as if it were trying to hide in shame. Classified in the genus calappa, what
distinguishes these crabs from others is their distinctly bulky carapace (upper
portion of the shell) which can reach lengths up to 3.5 inches and widths of nearly
5 inches. The calappa species became labeled box crabs because when threatened
these crabs pull their large pincers tight around their bodies, hiding their
legs under the canopy of their carapace, forming a well-armored “box”.
The shame-faced crab’s squat, rounded and convex shell may
be a rosy or yellowish hue with grooves and/or spots on it. The triangular
mouth, as well as its eyes, are generally hidden behind the large forceps of
its first pair of walking legs. In some species the impression of shame is
further enhanced by large reddish-pink spots on the pincers which make the crab
look even further embarrassed. The other pairs of legs are rather skinny since
they are rarely used.
The shame-faced crab generally remains in an inactive state,
burrowed in the sand, eyes looking upward, waiting for potential prey to come
by. It can remain in this position for several days, with only its eyes,
antennae and upper carapace protruding from the sand. Its forceps also protrude
to form a “breathing cave” behind them, preventing sand from blocking its air
passages. On the occasion that it does choose to run, it puts its body
completely upright and straightens its legs. To bury its self again, it simply
pushes its forceps against the sand like planks which then forces its body
backward into its burrow.
This crab’s favorite snacks are oysters, mollusks, snails,
and other marine invertebrates. Its specially formed forceps and right pincer
are well-adapted to pick its prey apart, and strong enough to crack their
shells. There is a large accessory tooth at the base of the moveable finger and
a corresponding flat plate on the fixed finger which act like a vice to crack
through the shell. The left pincer is relatively longer and sharper and used to
extract the gastropod’s body from the broken shell. This guy below in the video doesn't accomplish his task with lightening speed, but watch as he goes about getting some dinner.
