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Crustaceans of Zihuatanejo

SUBPHYLUM CRUSTACEA

-Animals (Kingdom Animalia)

-Arthropods (Phylum Arthropoda)

-Crustaceans (Subphylum Crustacea)

-Typical Crustaceans (Superclass Multicrustacea)

-Malacostracans (Class Malacostraca)

-Decapods, Isopods, and Allies (Subclass Eumalacostraca)

-Decapods and Krill (Superorder Eucarida)

-Decapods (Order Decapoda)

-Crabs, Lobsters, Shrimps, and Allies (Suborder Pleocyemata)

-True Crabs (Infraorder Brachyura)​

-Eubrachyuran Crabs (Zoosection Eubrachyura)

-Heterotrematan Crabs (Zoosubsection Heterotremata)

-Spider Crabs and Decorator Crabs (Superfamily Majoidea)

-Family Mithracidae

-Genus Pitho


Pitho crabs are compact and somewhat rounded compared to the long-legged appearance typical of many spider crabs. Their carapace is often textured or slightly bumpy, helping them blend into algae-covered substrates. Coloration commonly ranges from mottled brown and tan to greenish hues, providing effective camouflage among seaweed and reef growth. Unlike many decorative spider crabs that attach debris to their bodies, species of Pitho are more commonly associated directly with algae, where they both hide and feed. They are primarily herbivorous or omnivorous, grazing on filamentous and fleshy algae.

Pitho Crabs

Pitho (Genus)

Diet

  • Primarily herbivorous, feeding on filamentous, turf, and fleshy algae growing on rocks, coral, and other hard substrates.

  • Also consumes detritus and occasionally small sessile invertebrates such as bryozoans and hydroids.

  • Plays an important role in controlling algal growth on reefs and rocky shorelines.

Range

  • The genus Pitho is found in the tropical and subtropical Americas.

  • In the eastern Pacific, several species occur from the Gulf of California south along the Pacific coast of Mexico, Central America, and into South America.

  • Members of the genus are found along the Pacific coast of Guerrero, including the Zihuatanejo region, in suitable rocky and reef habitats.

Habitat

  • Inhabit rocky reefs, coral reefs, tide pools, rocky intertidal zones, and areas with abundant macroalgae.

  • Usually hide among algae, coral rubble, or beneath rocks during the day, becoming more active at night.

  • Their rough, spiny bodies often become covered with algae and other marine growth, providing excellent camouflage.

Size

  • Carapace width: 2–6 cm (0.8–2.4 in), depending on the species.

  • Leg span: Up to 12 cm (4.7 in).

  • Weight: Typically 10–80 g.

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