Basic animal anatomy

Well, I’ve been really into animation these past few months, as I was working on an idea of a cute animation trend, this theme came up.

My idea was basically to make 3 animations but I would ran out of time so I decided to work on only one, a cute animation of one of my favorite dogs: a chow chow puppy.

 

But before we begin, let's review some basic animal anatomy, starting with categorization. Animals have body structures that vary greatly from one type to another, depending on the natural evolution of each species. Of course, we can’t cover all of them (that would take ages) so here are some of the most common ones:

Canine, Felines such as dogs, cats, and foxes, usually have four legs and a flexible spine. Their movement is defined by the rhythm of the back and the way their weight shifts as they walk or run.

Ungulates, like deer, horses, and cows, have hooved feet and long limbs. Their bodies can be either slender or large, and their leg angles create a sense of elegance and stability in motion.

Rodents and small mammals, such as rats and rabbits, have compact bodies, quick movements, and a large head-to-body ratio. They also feature distinctive square front teeth, which play a key role in their vegetarian diet.

Birds, including eagles, parrots, and owls, have lightweight bones and wings built for balance and controlled flight. Their posture and the way they fold their wings are essential for conveying realism and grace.

Reptiles, like snakes and lizards, have elongated spines, scales, and flowing body curves. Their movements are fluid and continuous, often emphasized by the texture and flexibility of their skin.

Aquatic animals, such as fish and dolphins, possess streamlined forms and tapering shapes that allow them to glide smoothly through the water. Their anatomy emphasizes flow, curvature, and a sense of effortless motion.

As you can see, not all animals are the same. The evolutionary tree has diverged so much in terms of genetics that each type of animal has developed its own unique structure and survival mechanisms. Whether for eating, moving, flying, hiding, hunting, or simply surviving in its natural habitat.

 

These habitats can range from freezing mountain peaks and scorching deserts to deep, dark oceans, caves, or even high places like the top of a building.

 

Understanding why these specific traits exist is essential when designing or interpreting an animal, as it helps you visualize how its form and function work together.

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Studying

When studying a specific animal for artistic purposes, your first step is always to identify the category it belongs, then the characteristics of the species, and so on, here’s a quick example of how we can do it, let’s take the dog for example:

Observation

Starting by observation, and I’m not only talking about photos, I’m also talking about 3d models, skeletons, and other people’s art, gathering quality material for references and observation is a must have in this step, and after you have the glimpse of how the the animal “looks” its time to “separate” it for a proper study.

 

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Of course, you can find some assets to study as well:

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Skeleton: It doesn’t need to be perfectly realistic, nor do you need to know every single bone in the animal’s body. Understanding the basic joints, skull, chest, and pelvis is enough to grasp how the overall body structure works at a fundamental level.

Muscles: Muscles define the visible structure of an animal. Learning the main ones helps you understand how the body’s shape and movement come together.

Details: Pay attention to features like the head, ears, and paws. Observing these key parts will help you capture the unique traits and personality of each species.

Joints: Joints are essential for understanding how an animal moves. They show not only where the body bends, but also the limits of each motion.

Diversions: It’s crucial to understand the differences between species within the same category. Even though animals may belong to the same group, it’s easy to assume their bodies function in the same way—but that’s not entirely true. While there will be similarities, there are also important differences to recognize.

 

For example, here are some basic visual differences, as well as variations in proportions and joints, between dogs and cats in art:

Both are mammals, but clearly different, build to survive in different environments and different life styles.

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Animation Project

Now, let’s head to the animation project inside csp, if you never used this feature before, let’s get a quick look how you can set up your animation project in a simple way:

 

 

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File > New

 

Le’ts set the animation project, first, we choose the width to be 920 and height 1280, this is the short video format they usually use in youtube:

 

 

Now let’s create an animation folder on the timeline, and add a folder as cell, cells are the drawings that will compose your animation, and as the cell is now a folder, you can fit a lot of layers inside of it.

You can also pick a color for your folders, it helps keeping everything neat and organized, and as we will be using a lot of folders, it might be useful later

 

 

Animation base

To start the animation process, we first need to hand-draw a reference sheet for our character. For my version, I chose one of my biggest obsessions when it comes to dogs: the cream Chow Chow — a big, fluffy furball that almost looks like a bear. Their thick double coat makes them look like an actual plush toy, and sometimes their tongue has a dark blue or gray color, which I think adds even more to their aesthetic appeal.

 

But I’m not using an adult one — I wanted to animate a cream Chow Chow puppy instead, since it would be even cuter (and easier to animate). So first, after gathering some references and studying basic dog anatomy, I created a sketch page to explore what the character could look like in my style. I wanted to simplify the design to make the animation process easier, so I decided to give it very short legs and a cute, small face. Here’s my sketch page:

 

 

And here’s the final reference sheet:

 

 

You can add your image reference as a pop up window by using the Sub view option (Window > Sub view > add image)

Draft

Now that we have our reference sheet, let’s start drafting the animation. We’ll begin by drawing some curved lines to serve as movement guides. The idea is: you’re throwing a frisbee to a Chow Chow puppy, and he excitedly jumps up to catch it with his mouth, then lands gracefully on the other side. It might sound a bit complex, but by using these movement guidelines, I think we can make it work!

 

 

Then, let’s create two balls and overlap their movement in a way they will meet in the middle, this is will be the frame where the puppy will get to bit the frisbee:

 

 

Keyframes

Let’s now add some key frames to our animation, by directly sketching our character on top of our movement guidelines, trying to keep the consistency and proportions of the character, if you have difficulty doing that, try simplifying it in 3d shapes, like this:

 

 

Then we can have a better control of what Its proportions should look like in all angles:

 

 

After sketching the key-frames, it looks like this, and about the labeling, In some studios or projects, especially digital ones, labels like “A1” or “B1” can mark scene, layer, or cut numbers.

 

 

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“A4” might mean Scene A, drawing #4, or Layer A, frame 4. These labels help keep track of which drawing belongs to which sequence or cel layer.

 

For example, A1, A2, A3... could represent frames for the same moving element, such as a character.

 

while B1, B2... might indicate another layer, like a background object or a secondary character.

 

I like using these labels to keep track of how many frames I have available to draw between my keyframes, and to better plan the animation’s pacing when I start adding inbetweens and smear frames.

 

 

Speed/timing charts

in animation, “speed” refers to how fast or slow an object or character moves in-between frames. It’s not exactly a formal animation principle term (animators usually say timing or spacing), but it’s still a useful concept to describe the speed and rhythm of movement.

 

 

There’s tons of ways you can organize your keyframes to make different speeds in your animation, but here’s some of the most commons:

 

1. Even Spacing (Constant Speed)

 

Frames are placed at equal distances apart.

 

The motion is steady, robotic, or mechanical.

Like a car cruising at a constant speed.

 

Example: |—|—|—|—|—|—|

 

 

2. Ease In & Out (Slow Start and End, Fast Middle)

 

Frames are tight at the beginning and end, with wider spacing in the middle.

 

Makes movement feel smooth, natural, and organic.

Perfect for head turns, hand gestures, or bouncing.

 

Example: ||——|——|——|——||

 

 

3. Ease Out & In (Fast start, Slow middle, Fast end)

 

Frames are farther apart at the start, then closer towards the middle, and farther apart at the end again.

 

This chart creates acceleration or “speeding up, then desacceleration and acceleration again.

It'salso used when something starts moving up and then falling down.

 

Example: ||———|-||-|———||

 

 

For my timing, I chose an ease out/in motion, since the dog will jump in an arched movement — slowing down at the peak and then speeding up again right after. As for the frisbee, it will start off fast and then gradually slow down at a steady pacing.

 

 

When dogs jump, I noticed something really interesting about their poses. As they leap upward, their belly and chest become completely exposed to the camera. Then, as their body follows an arched motion, it shifts to the side and their hindquarters lift. By the time they come down, the pose changes to reveal mostly their back, and it’s basically the key poses you can use to make this movement:

 

 

Smear frames

Smear frames are intentionally distorted or stretched frames used to create the illusion of fast movement or motion blur between two poses.

 

The first one is a classic smear frame:

 

 

The second one is a smear frame that’s used in a really fast motion, it’s usually drawn with several drawings in the same frame:

They appear for only one or two frames, but they make the movement feel smoother, faster, and more energetic — especially in 2D animation.

 

In this case, we will be using smear frames to create an illusion of movement of the timing when the dog accelerates, by jumping, floating and then landing, we can add then around here:

 

 

We also gonna draft the frisbee flying around, making it smaller the more it aproachs the intersection between the dog arch and the frisbee arch, the entire movement might look like this:

 

 

And now, our animation draft is complete:

 

 

Vector lineart

When linearting your animation, it’s interesting to keep track of what size your pencil is, in my case, I used a solid 6 PX hard brush in the dogs lineart, and some variations for the others objects like the hand and the frisbee.

 

 

Now let’s add a vector layer to create our line art animation. Personally, as an amateur in traditional animation who’s currently studying motion design, I like to reuse my frames whenever possible—especially the line art. I often distort or modify existing drawings to create new frames without having to redraw everything from scratch.

 

 

However, this can be a destructive process, and regular raster layers will lose quality over time if you do it too often. By using a vector layer (which doesn’t degrade in quality), you gain more freedom to reuse and adjust your line art safely. Of course, you’ll still need to redraw many frames, but this approach helps reduce the overall workload significantly.

 

 

I’m not really sure how much of this technique is used—or if it’s used at all—in professional animation, so take it with a grain of salt. It’s not exactly an easy method either; you’ll need to spend some time learning how vector line art can be adjusted in Clip Studio Paint before applying it to your frame recycling process. But if you’re interested in trying it out, I think I can share a few tips:

 

Correct line > Pinch vector line tool can help you easily distort your lineart into smear frames for example:

 

 

By selecting: Operation of transparent part > Select area by dragging > Control point, you can now Box select your control points and edit them:

And at Edit > Transform you gonna find some really useful editing options for your lineart, like skew, mesh, free transform:

Coloring

This is probably the easiest part. Let’s set up our Lasso Fill tool with edge recognition, so when you circle your object, it fills automatically.

 

 

And now for an final extra step, let's add a little bit more of motion on your smear frames by blurring them with motion blur, this technique is not commonly used in 2d animation, it's actually mostly used in motion design specifically, where you have tons of interpolation options to use in your frames, but this effect is completely optional, so you don't need to feel obligated to use it, especially when working with bigger animations, but doing so in smaller ones really gives it that motion design vibes to it, I think it's cool.

There you go, I hope some of these tips were useful <3 thanks for reading.