In DS9 the "Adversary" a changeling takes over the ship. I'm not exactly sure how he takes over the ship. But what I really don't understand is why Dr. Bashir doesn't scan the crew to see who isn't human. Odo has said many times he doesn't have a stomach and can't process food. Why didn't they just make everybody eat something.

Didn't they have other and better options then running around firing phasers at wide bursts all over the ship?

I'd like to clarify my question.

They did do a blood test that didn't work because the "Bashir" doing the hypospray blood test was the changeling, who manipulated the test. They discovered shortly after the test that "that" Bashir was a changeling.

Remember this was the Federation's first encounter with a changeling besides what happened on their homeworld when the crew of the defiant was hooked up to a machine. The members of the crew learned almost nothing about changelings during that time, being as their brains were hooked up to a simulation.

At this point in the series the Federation didn't know much about the changelings. Almost all of their knowledge was from Odo. Odo could not digest food, did not have a stomach, etc. Why not try that? They had no idea at this point what could or could not work.

My question was specifically about this episode, not later episodes, or using knowledge from later episodes in the series.

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    It's been a while since I watched those DS9 episodes, but was that during the time that Bashir himself was a changeling? (That could be one reason why Bashir didn't try harder to detect the changeling.) Also, other changelings might be better at tolerating and pretending to eat solid food than Odo.
    – Praxis
    Commented Jun 10, 2015 at 10:02
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    I recall an episode where Odo said something like "If you scan me while I was a rock, you would see a rock". Obviously it is a big step from rock to humanoid, but it is possible that their metamorphic abilities give the Changelings the ability to fool scans. Commented Jun 10, 2015 at 11:30
  • yes the reasons the changlings were so effective, is because they were dam near 100% perfect clones, were talking like 99.999 repeating percent accurate. it wasnt until the end of the dominon war i believe until they found more accurate ways to scan for them.
    – Himarm
    Commented Jun 10, 2015 at 13:06
  • @Praxis Bashir did administer a blood test, and he was a changeling at the time. He somehow manipulated the blood test on one of the crewmen before he tested himself and put some of his goo in the hypospray container. Once they walked down the hallway, and the real bashir tried to come through a force field did they realize that the other Bashir was the changeling.
    – JMFB
    Commented Jun 11, 2015 at 0:31
  • @JMFB : Ah yes, I recall the episode more clearly now --- thanks. :-)
    – Praxis
    Commented Jun 11, 2015 at 0:51

2 Answers 2


Odo isn't as skilled as other changelings, as we have seen if they want to become a person they are essentially indistinguishable to scans. The only sure fire way was to shoot everything with a phaser or in invasive procedure where they removed part of the body (usually blood).

And the blood test wasn't 100% either, it was circumvented a few times, and Sisko's father even gave a way around it, that actually ends up in producing real blood.

A skilled changeling probably does simulate a stomach and digestive acids if they need to.

It comes down to practicality, they could do a phaser sweep every 10 minutes and test everyones blood every 30 minutes. But that will cause the dissension within Star Fleet that the changelings want. Make people distrustful and disrupt their work.

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    Weren't the blood tests (even dripping, see Gowron) - and phaser sweeps useless, and only worked on inexperienced Odo?
    – Petersaber
    Commented Jun 10, 2015 at 12:25
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    @Petersaber the hypospray blood test would be more reliable that the Klingon way, at the very least they could test the blood and see if it belonged to someone else.
    – Rigas
    Commented Jun 10, 2015 at 13:12

This is an old question but what makes you think they didn't scan everyone.

The ships sensors can identify a species so they wouldn't have to scan each person individually. The real doctor was behind a force field so he may not be detected. It wasn't relevant to the story that the scan turned up nothing and wouldn't effect the story.

Also Odo linked with the female changeling the first time the met in 'The Search' so its likely Odo knew that they were better at shape shifting than he was. We also know that you can't hide everything when you link as Odo knew there was a Klingon spy after he joined the great link.

I haven't watched the episode in a long time but I think that the reaction when Odo say something like 'it can't be you as you're bleeding' seemed like a eureka moment for all of them. It sounds like they had run out of ways they thought they could detect the changeling with at the time. It makes sense that they had eliminated all ways the knew of from studying Odo's ability's and were looking for something that would distinguish a 'rock from a rock' at that point.

So the obvious answer is that they had tried everything already and that's why they resorted to phaser everything until it dies (not very starfleet but its all they had left). It wasn't until Odo saw blood that they realized they missed a way.

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