Species

thumb|right|300px|A Gran alongside a Gungan, Herglic, and H'nemthe
Species were unique lifeforms. They were generally divided into three classifications based on their level of sentience: sentient, semi-sentient, and non-sentient. There were over 20 million sentient species known to the galaxy.Tales of the Bounty Hunters, p301.The Last One Standing Sentient species were sometimes erroneously referred to as races, which more accurately referred to groups or subspecies within a species.Galaxy Guide 4: Alien Races
==Lifeforms==
The five characteristics of lifeforms were organization (a distinct form and appearance), irritability (the ability to respond to external stimuli), metabolism (the ability to convert energy to stay alive), reproduction (the ability to create new lifeforms), and adaptation (the ability to change as their environments change).Galaxy Guide 8: ScoutsAlien Encounters
The predominant form of sentient life in the galaxy was carbon-based lifeforms. However, other forms of sentient life did exist, such as silicon-based or energy-based lifeforms. Reports from remote parts of the galaxy even mentioned giant clouds of interstellar gas which had evolved a form of intelligence based on internal force-fields.Star Wars Official Poster Monthly 16 Across all species, the majority were oxygen breathers, although a number breathed other substances such as ammonia, cyanogen, methane,Ultimate Alien Anthology methanogen,Shield of Lies helium and Dorin gas.The New Essential Guide to Characters Despite these differences, most species were easily classified into a number of distinct categories:
Mammalian sentient species were warm-blooded vertebrates, who nourished young through secretions from mammary glands. Most mammals were covered in hair. Some of the most prominent species in the galaxy were mammals, such as the Humans and their numerous offshoots, and the Duros. Other notable forms were Wookiees, Bothans and Sullustans.
Reptilian sentient species were cold-blooded vertebrates, typically covered in scales or bony plates. They typically evolved from species such as lizards, snakes and crocodiles. Most reptiles were land based, and lay eggs to reproduce. Reptilian sentient species were also very common in the galaxy, and notable examples included the Rodians, Barabels and Trandoshans. They also came in less humanoid forms, such as the Slith and Ssi-Ruu.
Plant sentient species synthesized energy from water, nutrients and sunlight. As such were usually immobile, although some species were able to move to seek better soil, light or nutrients. The Neti and Ergesh were two examples of this form of life.
Insect sentient species were arthropods, with defined body segments; most commonly head, thorax and abdomen. Many had hard exoskeletons, wings, and could have any number of segmented legs.Note: This differs from Earth classifications, where insects can only have six legs. Some insectoid species evolved into different forms, such as humanoid insect species. Common examples of this form of life were the Verpine, Fefze, Killik, Bartokk and Geonosians.
Hard invertebrates had hard outer bodies with no internal skeleton. These often included crustaceans, and some flying creatures. While this classification also included insectoid species, they were grouped separately. Examples of hard invertebrate sentient species included the Sauvax, the Aganof and the Tarc.
Soft invertebrates were descended from soft-bodied species with no bones, such as octopi, slugs and worms. Sentient species of this origin took many diverse forms, such as the Iyra, Hutt and Ee.
Avian sentient species were warm-blooded, feathered and winged creatures. They typically had light bones and strong muscles, needed to enable flight. However, many sentient avian species had lost the ability to fly. Examples of this kind included the Vor, Mrlssi, Quor'sav, Rishii and the Tikiarri.
Aquatic sentient species were those descended from marine life. These lifeforms often fit into other categories, but were classified together. Aquatic lifeforms included those that could breathe water, air, or both. These include the Mon Calamari, Selkath, Nautolan, Quarren, Herglic, Dellaltian and Gungan.
Craniopod sentient species were, despite these broad categories, lifeforms so truly alien that they did not fit easily into any of the common categories. These were categorized as exotic sentient species, and included the Bith., Celegians, the Filar-Nitzan and the Pulra.
==The study of sentient species==
Many institutions in the galaxy focused on the study of sentient species. The most notable were the University of Coruscant.The Essential Guide to Alien Species and the University of Sanbra. Those scientists and anthropologists that studied sentient species were known as sentientologists.
One of the major works on sentientology, Obo Rin's Catalog of Intelligent Life in the Galaxy, was commissioned by Lord Vader, and was carried out under the auspices of Major Vontenn, Liaison Officer of Sentiology Studies. While it contained much information, it was also a conduit for Imperial propaganda, and as such, had a tendency to depict some species as less developed than was actually the case. Rin's credentials as a scientist were also questionable.Galaxy Guide 4: Alien Races, first edition
Another major work on sentientology was The University of Sanbra Guide to Intelligent Life by the Iyra Tem Eliss. Rather than a scientific study, it was designed to facilitate first contact with species, providing "guidelines as to common cultural interests, goals, fears and drives." However, it departed from Imperial doctrine on a number of points. The Empire tried to apprehend its author shortly before publication, but the academic escaped and released his research through underground networks and NewsNets.Galaxy Guide 12: Aliens — Enemies and Allies
The Shi'ido researcher Mammon Hoole wrote the acclaimed The Essential Guide to Alien Species. He was able to gain unique insights into species by infiltrating using his shapeshifting abilities. Other documents that detailed sentient species included the Universal Encyclopedia.
==Behind the scenes==
Species in the Star Wars universe generally have a large compatibility to real-world classification systems. However, these are not always strictly adhered to. For instance, according to The Essential Guide to Vehicles and Vessels, the Colossus wasps "follow the standard insect physiognomy, with a head, thorax and abdomen,"The Essential Guide to Vehicles and Vessels, 88. which corresponds with the real-world physiognomy of insects;Insect on Dictionary.com however, the Sic-Six, which also have these three body segments but eight legs, are classified as arachnids,Galaxy Guide 4: Alien Species which in the real world have only two body segments.Arachnid on Dictionary.com Star Wars also has numerous examples of species sharing characteristics from different classifications, such as the Quor'sav species. They have a combination of monotreme—mammals that lay eggs—and avian characteristics.
==Sources==
*Galaxy Guide 4: Alien Races
*Galaxy Guide 8: Scouts
*Galaxy Guide 12: Aliens — Enemies and Allies
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*Alien Encounters
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*The Essential Guide to Alien Species
*The New Essential Guide to Alien Species
*Alien Anthology
*Ultimate Alien Anthology
*Star Wars Official Poster Monthly 16
*Star Wars: Knights of the Old Republic
*Star Wars: The Official Figurine Collection 55 
==Notes and references==
==External links==
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