Parasite (Blake's 7)

These '"parasites"' are sapient but primitive humanoids which inhabit a planetary life form known as "the Host".

Biology
They have tan-colored skin and spade-like hands with fused digits, which allow them to dig into the soil to feed on the Host's "life" substance. They are born from eggs, and seem to be born similar to the adults in size and shape.

Culture and society
"Parasites" have sapience, individual names, and are fully capable of speech, but don't seem to have a true civilization or society, as they are constantly moving and prefer to stand alone, to make it easier to conceal their presence from the Host.

When the Host detects "parasite" activity, it opens up fissures on the ground to absorb them, and may also clean entire landmasses by covering them in digestive seas with a composition similar to saliva. The "parasites" live in fear that the Host will notice them, and therefore never stay in a single location, preferring to move continuously.

Despite preferring isolation, they have shown signs of parental care, with adults teaching and protecting the newly-hatched.

Appearances

 * Blake's 7, s02e06, "Trial" (1979)