Cambaridae is the largest of the three families

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 of freshwater

Freshwater

Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...

 crayfish

Crayfish

Crayfish, crawfish, or crawdads – members of the superfamilies Astacoidea and Parastacoidea – are freshwater crustaceans resembling small lobsters, to which they are related...

, with over 400 species. Most of the species in the family are native to North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

 east of the Great Divide

Continental Divide

The Continental Divide of the Americas, or merely the Continental Gulf of Division or Great Divide, is the name given to the principal, and largely mountainous, hydrological divide of the Americas that separates the watersheds that drain into the Pacific Ocean from those river systems that drain...

, such as the invasive species Procambarus clarkii

Procambarus clarkii

Procambarus clarkii is a freshwater crayfish species, native to the Southeastern United States, but found also on other continents, where it is often an invasive pest. It is known variously as the red swamp crawfish, red swamp crayfish, Louisiana crawfish, Louisiana crayfish or mudbug.-Range and...

and Orconectes rusticus

Rusty crayfish

The rusty crayfish, Orconectes rusticus, is a large, aggressive species of freshwater crayfish which is native to the U.S. states of Indiana, Kentucky, Ohio, and Tennessee...

, with fewer species living in East Asia

East Asia

East Asia or Eastern Asia is a subregion of Asia that can be defined in either geographical or cultural terms...

 and Japan

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

, such as zarigani

Zarigani

Zarigani is a species of crayfish endemic to Japan.It is small in size and grayish in color. Its front claws are much weaker than those of other crayfish. Zarigani need low temperature and high water purity, so they live in upper streams of rivers or lakes in highland regions...

 (Cambaroides japonicus).

A 2006 molecular study suggested that the family Cambaridae may be paraphyletic

Paraphyly

A group of taxa is said to be paraphyletic if the group consists of all the descendants of a hypothetical closest common ancestor minus one or more monophyletic groups of descendants...

, with the family Astacidae

Astacidae

The family Astacidae comprises the freshwater crayfish native to Europe and western North America. It is made up of three genera. Pacifastacus is found on the Pacific coast of the United States and British Columbia and includes the signal crayfish and the Shasta crayfish...

 nested within it, and the status of the genus Cambaroides

Cambaroides

Cambaroides is a genus of freshwater crayfish. It contains seven species:*Cambaroides dauricus*Cambaroides japonicus*Cambaroides koshewnikowi*Cambaroides sachalinensis*Cambaroides schrenckii*Cambaroides similis...

remains unclear.