Drawing requires that you pay attention to every detail—even the seemingly unimportant ones. In creating an image (no matter how skillfully), the lines and tones on the paper provide ongoing feedback as to what you have observed closely and what you have not.

Scientific illustrations can achieve certain things that photographs cannot. A good illustration can portray difficult-to-photograph or rarely witnessed events. It can incorporate everything that’s important into one single image or show a special view of a subject.

It would be next to impossible to observe, in nature, a dozen different aquatic species in their natural habitat, posing perfectly together and all in focus at one time—but such a scene can easily come to life in an illustration.

My studies of live animals usually begin with a series of quick drawings, all on a single page. When the subject changes position—which it pretty much always does—I abandon the first sketch and start a new one. Continuing on in this way, the page fills with mostly unfinished squiggles until the animal eventually resumes one of its earlier poses. If that happens, I add as much detail or refinement to one of the easier sketches as I can. While this is all going on, I also jot down written notes that help explain what I observed and what seemed significant.

In-person, live observation of color is a practice for which I feel there is no adequate substitute. Photographs are often imprecise in reproducing color.

Focus on the negative spaces surrounding the object to give yourself a fresh perspective on the form.

Colors in nature are, in general, more subdued than what comes directly from the pencil or the tube of paint. Greens, especially, tend to be a lot browner than we expect.

Leave the drawing unfinished. Record as much information as you need, but don’t draw any forms, details, or colors that are merely repetitive. The back and front of a representative flower on a plant, for example, or half of a bilaterally symmetrical animal may be all that’s necessary.