The pouch contains four mammary glands but only two of them are active at a time. The joey exits the pouch permanently at six to ten months depending on the species. The young continue, however, to suckle by sticking its head in the mothers pouch. This arrangement continues until the joey is twelve to eighteen months old. The most famous kangaroos are the two most common species of large kangaroos.
Large kangaroos are terrestrial, primarily vegetarian grazers.
Shepherds complain about overgrazing of kangaroos, however, in reality, sheep are more often accused of destroying pastures. The more unknown Wallaroo is stouter, while wallabies are a smaller species of kangaroos. They are about the size of rabbits. In fact, one species of wallaby is actually called the hare wallaby because of it's close resemblance to the hare. The nail-tailed wallaby are named because of the horny nail on the tip of their tails.