I had never really known the name but thats the name used for the tricycles used in an article in today El Semanario to describe these vehicles you can hire at the pier to transport your luggage at the passenger ferry pier. According to the article, the normal rate at the ferry pier is 30 pesos and can range from 100 to 200 pesos for transferring large amounts to the interior of the island. According to the article, their are 24 of these and they are members of a union. They also are available at the cruise piers but no set fee there--they work for tips.
The article is in spanish but I put the link because I found the photos interesting. These guys can handle much cargo!