picture by J R Compton. http://www.JRCompton.com/photos/The_Birds/J/

Classification

Domain: Eukarya
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Superorder: Galloanserae
Order: Anseriformes
Family: Anatidae
Subfamily: Aythyinae
Genus:Aythya
Species:Aythya affinis

image courtesy of J R Compton http://www.JRCompton.com/photos/The_Birds/J/

Why Eukarya?
The Lesser Scaup is like other Eukaryotic organisms in that it is multicellular and the cells it possesses each have a true nucleus as well as membrane-bound organelles. Each cell divides via mitosis and contains multiple linear chromosomes which are both characteristics of Eukaryotes. Also members of the species Aythya affinis partake in true sexual reproduction, which is unique to the Eukarya.

Why Animalia?
The Lesser Scaup can be classified under the Animalia because it is a multicellular, eukaryotic heterotroph that lacks cell walls. It is also mobile, like all other animals at some stage in their life.

Why Chordata?
The phylum Chordata is home to organisms that at one time or another have all possessed a notochord(or skeletal rod), pharyngeal pouches, an endostyle(thyroid gland), a postanal tail, and a dorsal, tubular nerve chord. Because the Lesser Scaup matches this description it can be classified under this phylum.

Why Aves?
The class Aves is home to the Birds, which can be defined as vertebrates with feathers. This class is capable of aerial flight. Because Aythya affinis meets this description it belongs to Aves.

Why Anseriformes?
The Anseriformes are a group of birds with webbed feet that are highly adapted to water. Another characteristic that species in this Order share is a broad, flat bill. Lesser Scaup definitely have these features and are therefore a part of this Order.

Why Anatidae?
The Family Anatidae is home to all ducks, geese, and swans. These organisms are all waterfowl that are generally herbivorous with the exception of aquatic invertebrates. Many Anatidae are usually monogamous for a year and then find new mates for the breeding season of the next year. As you'll find out, Lesser Scaup are a match for these descriptions.

Why Aythya? 
Aythya is a genus of Anatidae designated specifically for diving ducks, therefore because the Lesser Scaup is a pro at this fascinating approach to feeding it belongs in this classification.

Why affinis?
Lesser Scaup are designated the species name affinis which translates to  neighboring, adjacent, related, akin, connected, or next.

             (Click on the image to the left to view the phylogenetic tree that Aythya affinis fits in beginning at Animalia)

The phylogenetic tree located in the image above shows a broad resolution of where Aythya affinis fits in the grand scheme of organisms beginning with Animalia. This phylogenetic tree was constructed based on morphology. The phylogenetic tree located below depicts a more refined resolution of Aythya affinis' evolutionary rank in relation to other species belonging to the genus Aythya. This specific phylogenetic tree was constructed based on morphology of the skeleton, trachea, and integument.

       (Click on the image to the left to view the phylogeny of the species closely related to Aythya affinis)

               Find out about where Lesser Scaup live in Habitat and Geography
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