Classification of taxonomy of extraterrestrial living entities (aliens) is based on descriptions in the Padma Purana. Major classifications of aliens are based on
(1) dominant gunas (mode of nature, whether they are sattvic, rajasic or tamasic),
(2) physiology and origin;
(3) realms (heavenly, earthly or subterranean); and
(4) chemical compounds that build their molecular basis.
Classification based on dominant gunas
Extraterrestrial beings (aliens) are categorized into three major types, namely the suras (benevolent beings), manusas (mortal human beings) and asuras (malevolent beings). It is based on dominant modes that influence their mentality, whether it is sattvika (goodness), rajas (passion) and tamasika (ignorance). Animals and plants do not specifically fall into this classification, but other texts such as Ayurvedic texts do mention about plants and animals with sattvic, rajasic or tamasic. This classification is a general divisions among good and bad intelligent life in the universe. The demigods, siddhas, caranas, and vidyadharas are classified as suras, while demons such as the bhutas, pisacas, reptilians, and goblins are classified as asuras. In between, the human beings, struggle to be free from asura influences to elevate themselves to heavenly realms with sura qualities.
Classification based on physiology and origin
The lowest kinds of living beings are said to depend on water when they breathe. This type of living beings is called the jalajas (aquatic and amphibians). According to Backster (2003), in different planets with suitable intensity of abiotic components, living entities can grow into more intelligent and complex beings. For instance, a reptile on Earth can grow into intelligent reptiles in a more suitable planet with more suitable atmosphere, sun rays, soil condition and oxygen level. So, intelligent alien life can truly exist on other planets although on Earth they may not grow in maximum rate due to unsuitable abiotic conditions.
Krimayas are bacteria, viruses, mono cellular beings, mollusks, larvae, and worms. In other planets there are alien beings of this type who could think as human beings do. They build cities and roam the space with space crafts. In the Atharvaveda it is mentioned about this type of extraterrestrial beings who fall on Earth and create disturbances. The krimayas are afraid of hot temperature, therefore their origin planets are naturally damp and dark.
Sarabhas are family of the krimayas, in the forms of insects and arachnids. They thrive in optimal expressions on a planet with a high oxygen level. The more oxygen they get, the bigger and more intelligent they become. The Bhagavata Purana mentions about ruru species which belongs to krimaya. It is mentioned in the Bhagavata Purana that rurus do not exist on Earth, but more ferocious than a snake.
Sthavaras, or the plants. Their actual habitat is said to be on the moon. Because moon is described as a cooling and fertile place (as per Visnu Purana, Padma Purana and Garuda Purana), plants naturally grow very well there. Sthavaras can heal any disease and are connected tightly to water and carbon. Some plants which produce medical substances, fruits and edible leaves can absorb moon light and turn it into tasty and nutritious compounds.
Rudranas, popular as the reptilian species. Reptilians are included in the asura clan, often remarked as malevolent to other living entities. Siva Purana, Lingga Purana as well as the Mahabharata frequently mention in many parts about malevolent activities of the reptilian races throughout Vedic history. Their clans are known as the nagas and uragas, and they have interactions with humans in the past. In the Mahabharata, it is mentioned that Arjuna married Ulupi, a naga prince. Then, the Siva Purana mentions about naga species who resided beneath Hindian Ocean and abducted humans for sustenance. One day they kidnapped a brahmana. This brahmana appealed for help to Lord Siva. Lord Siva then destroyed all the evil nagas and thus he is known as Nagesvara.
Pasunas, or mammals. Some pasuna species are in the form of half lion or half cow. Meanwhile, paksinas, or avian species. They reside on a planetary cluster called Kinnaraloka in the Bhuvarloka section of the universe. They have wings and feather, but they also can think and speak as humans do. Paksina species depend on sun rays and a lot of oxygen.
Manusah, or humanoids. Among the humanoids are human beings, devas, asuras, kinnaras (half human and half beast), kimpurusas (ape-like creatures), gandharvas (heavenly musicians), apsaras (angels), vidyadharas (winged angels), siddhas (super humans), and so on. The Padma Purana mentions there are 400,000 humanoid species in the entire universe.
Bhutas, or ethereal beings. This includes ghosts, bhutaganas (known as grey aliens in the western culture), pisacas (child-eating demon, as Pennywise), goblins, and so forth.
Classification based on realms of existence
This classification is found in the Bhagavata Purana, Canto 3 and 5. Heavenly realms are planets where devas, siddhas, caranas, vidyadharas, kinnaras and all good beings reside. Then, subterranean planets or the bila-svargas are planets where asuras, krimayas, reptilians and bhutas live. In between is the Earthly plane, or the Bhurloka, where spirits take birth and do particular activities for further entanglement in material existence or go back to Godhead.
Classification based on chemical compounds and molecular basis
This kind of classification is a combination between physiology and basic element(s) in the cells. For example, a mammal in a particular planet may be composed of different element from mammals on Earth. Such element might not be carbon (as dominant in Earth mammals‟ cells) but could be silicon, silver or copper. This anomaly is found in chemical compound of some Earth mollusks such as shrimp, whose blood contain copper element rather than iron, which thus makes their blood bluish. In the Mahabharata, as well as the Rigveda it is stated that Garuda‟s feather is made of special compound that could neutralize thunderbolt effect. Some Vedic Scriptures name it as suvarnapaksa, or „golden-winged bird‟. It could be concluded that Garuda‟s basic cellular element is gold (aurum) and calcium compound, unlike Earth birds, although they physiologically belong to the same avian species.
(Article by I.B. Arya Lawa Manuaba1 and I Nyoman Sudirman, English Education Department STKIP Suar Bangli, Bali)