sentence: in addition there are okapi , which bristol was one of the first zoos in the world to breed , asiatic lion , pygmy hippo , and red panda , among the 300 mammal in its collection , representing 50 species ( from a total of over 4,300 mammal species on earth ) the zoo 's twilight zone was the first of its kind when it opened , there are many other indoor exhibits including an insect and reptile house and aquarium meanwhile outside there are several aviaries and a seal and penguin enclosure .