Observer (The Nitrogen Fix)

The Observers are a mysterious species of sapient amphibious ichthyoids which inhabit Earth in the far future, in a time in which free oxygen no longer exists in the Earth's atmosphere.

Humans refer to this species as either "Natives" or "Invaders". The former stems from the misconception by some that these creatures have actually evolved on Earth, whereas the latter is closer to the truth but presumes a hostility not actually present in the Observers.

Biology
Observers are long, slender fish-like creatures, with mottled olive-green and brown skin, and weigh about 120 kg. They can operate on land or water, and survive equally well in an oxygen-rich or anoxic environment, since they do not breathe. When standing erect, they tower over the tallest Humans.

Observers are supported by four tentacular legs on land. The lower pair of legs is positioned close to the horizontal flukes which propel them while swimming, while the upper pair is about 50 cm higher. The upper part of the body is also equipped with a pair of tentacles, which are positioned below the eyes and above the lateral fins, while additional fine-handling tendrils surround the mouth, which is positioned at the top of their heads. Despite their awkward appearance, they can move on land faster than Humans.

An Observer's eyesight is far more acute than a Human's, as their two large eyes move independently of each other and are capable of telescopic vision and night vision. Their nervous system is based on mobile cells which store information directly and move freely through the circulatory system and tissues. Similarly, their muscular system is fluid, consisting of protean structures that can rearrange themselves, thus enabling their muscles to push as well as pull. Their blood is nearly colorless and kept in motion by hundreds of muscular pumps running along the walls of the blood vessels, as opposed to an actual heart or hearts. This anatomical tendency towards fluidity and decentralization results in the Observers being far more resistant to physical injuries.

Observers have no vocal apparatus, no respiratory system and no sense of smell, although they do have a sense of taste. Their sense of hearing is crude, unable to discriminate pitch and timbre. Their metabolism revolves around consuming both reducing and oxydizing foods in balanced quantities. They reproduce asexually by parthenogenesis. If the offspring turns out to be an imperfect clone, it is eaten by the parent.

Individual Observers are referred to as "units" and operate as part of a hive-mind. They have a disk of specialized tissue on their chests, about 12 cm in diameter, which serves to exchange information. Whenever two units meet, they press their chests together and exchange memory cells. At the end of the process, both "units" have access to the other's knowledge and memories up to this point.

Observers feel pleasure in collecting information and engaging in problem-solving activities, which is comparable to the pleasure that other species commonly associate with food or sexual activity. The act of exchanging memory cells is also pleasurable for them.

Culture and society
Observers travel through space frozen inside comet nuclei, seeking new worlds to explore and to bring back more knowledge to their gestalt mind.

Appearances

 * The Nitrogen Fix, by Hal Clement (1980)