are rhinos endangered species
1 Black rhinos, Sumatran rhinos and Javan rhinos are critically endangered, which is the list's highest risk category. 2  There are 5,055 black rhinos, fewer than 100 Sumatran rhinos and only 35 to 44 Javan rhinos.lack rhinos, white rhinos and Sumatran rhinos have two horns. Javan rhinos and greater one-horned rhinos have one. On the black rhino, the front horn can grow to 20 to 51 inches (51 to 130 centimeters), while the rear horn can grow to about 20 inches, according to the International Rhino Foundation.