Libinia emarginata occurs from Nova Scotia to the Florida Keys and through the Gulf of Mexico.

The eggs are initially a bright orange-red, but turn brown during development, which takes around 25 days.

Adults are sluggish and not aggressive, and younger crabs are frequently covered with sponges and hydroids.

[5] Despite its small size, in comparison to other predatory crabs, L. emarginata feeds on large starfish such as Asterias forbesi.

[7] Unusually for crabs, L. emarginata preferentially walks forwards, rather than sideways, although they are also capable of sidelong movement.