Illegal wildlife trade generates an estimated $19bn (£12.5bn) a year worldwide.
Federal and state authorities have charged more than 150 people accused of operating an online wildlife trafficking ring involving endangered animal skins and live birds.
The US Fish and Wildlife Service (USFWS) announced the arrests on Thursday after an undercover sting that included officers from 16 states, three federal agencies and three Asian countries.
Items seized under “Operation Wild Web” include the pelts of endangered big cats such as the Sumatran tiger, leopard and jaguar.
Authorities also seized live migratory birds such as the California scrub jay, whale teeth, elephant and walrus ivory and a zebra pelt.
“Our message is clear and simple: The Internet is not an open marketplace for protected species,” said Edward Grace, deputy assistant director for law enforcement for the USFWS.
Working with counterparts in several states, federal officials targeted illegal wildlife sellers who operate through Craigslist, eBay and other internet marketplaces and classified ads.
Wildlife officers in Singapore, Thailand and Indonesia ran similar operations at the same time.
The items were seized last August, although charges are still being brought in many cases.
Six Southern California residents were charged with selling endangered species and animal parts, the US Attorney’s Office in Los Angeles said.
Illegal wildlife trade generates an estimated $19bn (£12.5bn) a year worldwide and ranks fourth on the list of the most lucrative global illegal activities behind narcotics, counterfeiting and human trafficking, the animal welfare group said in a report last year.