Despite my joke about kids and animals, these same principles also apply to portrait photography of people.
Focus/Sharpness
The number one thing - make sure the photo is sharp and in focus, particularly the eyes, or in the case of the shark, other "notable" features, such as the teeth:
Get in close - use that zoom and/or blur the distractors
I believe that it's often hard to reveal personality though a photograph from a distance. If you want to reveal the subject of the photo, you often need to eliminate distractions in the frame; this can be done either through a selective depth of field or zooming in to fill the frame with the subject or a part of the subject.
This eagle looks like he's analyzing me. The specular highlight in the eye adds that little something extra to the shot (just happened to be there - no planning on my part).
Put the animal in context
On the other end of the spectrum from zooming in on a single subject is placing the subject within a broader environment within the frame. How you do this depends on the story you want to tell with the photo. In the case of the eagle and the mountain, I wanted to tell the story of this magnificent bird flying free above the Andes mountains in Ecuador.
For this next picture, I wanted to tell the story of a morning at the beach - we've got the sunset, a couple of birds on the water, and the early riser, who's basking in the early morning rays from the sun. This is a closer shot, there is more detail in the bird and you can see the light filtering through the large wing feathers.
Show the animal in action
This relates to putting the animal in context. We are telling a story, possibly more limited, that shows the animal doing what it does - flying, jumping, running.
In this case the eagle is diving in to catch a piece of meat thrown into the air by his handler.
Show relationships
Once again, this is related to a broader context, but this time we want to show the animal interacting with others - humans, animals - to tell a story about their relationships.
In this first one, the eagle is returning to his handler. The eagle lives on a rescue reserve and had been badly mistreated for some time. After a great deal of care and nurturing, he learned to fly, though he will never be able to return to the wild.
Quotes from "Nemo," anyone?
