The term 'Big Zoo Animal' can refer to a variety of animals, including the rhino (5 letters), HIPPO (5 letters), APE (3 letters), SEAL (4 letters), TIGER (5 letters) and ASS (3 letters). The rhino is a large mammal with a thick, grey hide and two horns on its snout. The HIPPO is an aquatic mammal with a large, barrel-shaped body and short legs. Apes are primates that are characterized by their long arms and lack of tail. Seals are semi-aquatic mammals that have flippers instead of feet and spend most of their time in the water. Tigers are large cats with distinctive orange and black stripes. The ASS is a hoofed mammal that is related to horses and donkeys.