butterfly crab

The nickname "butterfly crab" refers to the crab's butterfly-shaped carapace.

butterfly crab (plural butterfly crabs)

1. A species of shallow-water king crab (Cryptolithodes typicus) native to coastal regions of the northeastern Pacific Ocean
   • Hart, Josephine F. L. (1965 May) “Life History and Larval Development of Cryptolithodes typicus Brandt (Decapoda, Anomura) from British Columbia”, in Crustaceana, volume 8, number 3, →DOI, →JSTOR, pages 255–276: “The turtle or butterfly crab, Cryptolithodes typicus Brandt, 1849, is a crustacean of [...] the family Lithodidae.”
   • Fretwell, Kelly, Starzomski, Brian (2015) “Butterfly crab • Cryptolithodes typicus”, in Biodiversity of the Central Coast‎^[1], archived from the original on April 6, 2018: “The butterfly crab's range extends from northern Alaska to southern California.”