Hummingbird
Hummingbirds are birds native to the Americas and constitute the biological family Trochilidae. They are among the smallest of birds, most species measuring in length. Indeed, the smallest extant bird species is a hummingbird, the bee hummingbird weighing less than .
Heterandria formosa
Heterandria formosa (known as the least killifish, mosqu or midget livebearer) is a species of livebearing fish within the family Poeciliidae. This is the same family that includes familiar aquarium fishes such as guppies and mollies. "H. formosa" is not as commonly kept in aquaria as these species. "H. formosa" is one of the smallest fish in the world (7th smallest ), and is the smallest fish found in North America. Despite the common name "least killifish", it belongs to the family Poeciliidae and not to one of the killifish families.