How do I reference in a figure legend? I am citing a figure I have taken from a journal. In my figure legend do I only include the number citation or do I need to state the figure is taken from somewhere else?  

i.e Figure shows a cat [1]

or

Figure shows a cat. Taken from [1]

Thanks!
When you plan to reuse a figure taken from a journal paper, you should first ask permission to the copyright owner which, in most cases, is the journal publisher. Every publisher has its own procedure to make such a request, but usually you will be at least asked to specify where you want to republish the figure (in this case, specify PhD thesis).

The publisher will typically grant permission to reuse for free and it will also specify how it wants its copyright to be stated. Here are a couple of real examples:


  Reproduced with permission from [1] ©IOP Publishing. All rights
  reserved.
  
  © 2018 IEEE. Reprinted, with permission, from [1].


If your citation style is non-numeric, substitute the appropriate citation style.

In my experience, many people frequently overthink this procedure, as though obtaining the permission to republish could involve going through an obstacle course race, and sometimes they plan to spend hours to redo a figure which is just a few clicks away.