12.6. Couvs branchyrhynchos: American Crow http://www.ck12.org
Biology
Cell Biology
The American crow species contains eukaryotic cells. This type of cell features many different types of organelles.
All of these organelles serve a specific purpose. For example, the nucleus contains genetic material. The cellular
membrane is a skin around the cell that acts as a shield and keeps all the inner parts of the cells together. The
lysosomes are a crucial part of the cells. Its their job is to discard of any waste in the cell. The Golgi apparatus is
important because it sends protein to different places in the cell. There are still many more important organelles in
the eukaryotic cell.
Evolution
The American crow is to believed to have evolved in central Asia and spread to North America, where they adapted
to the climate very quickly. All birds first originated from a certain branch of dinosaurs called theropods. A dinosaur
fossil discovered in the 1960s named Deinonychus showed evidence of the evolution of flight. Dinosaur experts
believe that dinosaurs that lived among the trees lept into the air to run away from predators or to catch food,
resulting in wings. Another theory is that the early bird ancestors lived among the trees. The power of flight allowed
them to jump from branch to branch.
The American crow is often confused with the northwestern crow (C. caurinus). Its ancestors became separated by
Ice Age glaciation west of the Rocky Mountains. The two species are much alike. There is a marked difference in
voice, however.
Anatomy and Physiology
All birds are vertebrates, modified so they have the ability to fly. Birds are known to be the last existence of
prehistoric dinosaurs. Birds are warm blooded, unlike lizards and most reptiles. Birds have thrived throughout
history evolving, over the years to thrive in existence. They are unique to the kingdom of Animalia for their
pneumatic bones, meaning they are hollow. Their hollow bones allow them to fly and carry themselves in the air
easier. Birds have a four-chambered heart, which serves to deliver oxygen to the rest of the body. The four-chamber
heart helps to circulate blood so the body properly receives oxygen.
Behavior
The peregrine falcon is non-aggressive toward humans and animals that aren’t prey. This animal is solitary except
during mating seasons, when they mate, then care for young. They kill small animals like rabbits for food.
References