“Mexican” Spider Crab, Libinia mexicana: The “Mexican” Spider Crab is an odd looking crab with an inflated oval carapace (shell) and a long tubular rostrum (snout). The shells range from 5 to 6.5 cm in length and bear short brown hairs (pubescence) with six dorsal spines in a row down the middle of the back plus several other spines on both sides of the median row.
The claws (chelae) are white and much longer than the first walking legs which in turn are longer than the second pair. They are a low intertidal species found up to 50 meters deep in the water column in and around algae covered rocks and are also a by-catch of shrimp trawlers.
They have a limited range being found only throughout the Sea of Cortez.
The “Mexican” Spider Crab is a brachyuran crab and a member of the Majidae Family, which includes the spider crabs that are known in Mexico as Cangrejos. There are 60 different crabs that live in the Sea of Cortez, the majority of which have shells (carapaces) of less than one inch.
The small crabs are found in rocky, inter-tidal or shallow sub-tidal environments where they crawl among algae. They are also found in tidal pools. In contrast, spider crabs live in deep water on the continental shelf. They are not well known and rarely studied. All have long legs and shells that are longer than they are wide and have a point at the front. Most have bristles that they utilize to attach algae and other items for camouflage which gives rise to the common name Decorator Crabs.