Star Trek (1966–1969)
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Operation -- Annihilate! 

The Enterprise crew attempts to stop a plague of amoeba-like creatures from possessing human hosts and spreading throughout the galaxy.



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Episode complete credited cast:
Joan Swift ...
Maurishka ...
Yeoman Zahra
Peter Kirk (as Craig Hundley)
Fred Carson ...
First Denevan
Jerry Catron ...
Second Denevan


The Enterprise traces a virus-like outbreak that seems to be traveling in a direct line across a planetary system. The next planet is home to Kirk's brother Sam, his sister-in-law and their young son. The Enterprise arrives too late however for Sam. They find flying jellyfish-like creatures that attach themselves to humans. They take over the victims nervous system forcing them to bend to their will. Spock finds a weapon to use against the creatures but it leaves him hopelessly blind. Written by garykmcd

Plot Summary | Plot Synopsis


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Release Date:

13 April 1967 (USA)  »

Company Credits

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Technical Specs


Sound Mix:


Aspect Ratio:

1.33 : 1
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Did You Know?


Stock footage of Leslie's hands from Star Trek: The Alternative Factor (1967) is used to represent the personnel in the satellite control room. This shot was removed from the remastered version of the episode. See more »


(at around 10 mins) There is a person moving in and out of the frame way behind the action during the outdoor sequence. See more »


Denevan Pilot: I did it! It's finally gone! I'm free! I'm...
See more »


Spoofed in Buffy the Vampire Slayer: Bad Eggs (1998) See more »

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User Reviews

Flying, Buzzing, Telepathic Jellyfish Body Snatchers!
7 June 2007 | by (Vulcan) – See all my reviews

The Enterprise is going to investigate what appears to be a very slow-moving viral form of mass-hysteria which has, over centuries, brought several thriving civilizations on many different planets down. Spock reviews the epidemiology of the phenomenon at the beginning of the episode, revealing that the trajectory of the epidemic places a Federation colony directly in its path. Sam Kirk, his wife and their son, live in this colony.

Captain Kirk is directly affected by his family's involvement in all of this, and Shatner does a very nice job of portraying a captain whose professionalism and rational judgment are threatened, and whose usual rational support structure (Spock) is also imperiled and unavailable. In a scene which was, unfortunately underexploited by the mediocre script, Dr. McCoy rises to the occasion and, surprisingly, fills both his usual role and that of the great first officer.

Herschel Daugherty directs this memorable episode of TOS, and does an admirable job with a somewhat weak script. The Stephen Carabatsos script creates some problems for the acting (particularly Nimoy, Barrett and Kelley), and - like his previous effort "Court Martial" - makes the pace a bit inconsistent. Kelley and Shatner are truly remarkable despite these challenges.

The episode also uses setting very nicely, with a very minimal use of backdrops and carefully chosen locations for rare open air shots. Additionally, Spock's character is very nicely examined, the developing rivalry and friendship between McCoy and Spock is enhanced, and the powerful - though unresolved - relationship between Christine Chapel and Spock begins. Finally, this (and the great earlier City on the Edge of Forever)is one of the first episodes to exploit the (unfortunately largely overlooked and unrecognized) subtlety of William Shatner's acting ability by placing Kirk's personal life in the way of his professional practice. This became a major theme as the series continued into its 2nd and 3rd seasons.

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