Largemouth Bass Anatomy: Master Your Approach

There are many different species of bass in the United States. Some of them look extremely similar, especially during earlier stages of life, and some of them are so far detached from the general bass look that you wouldn’t even think they were part of the family.

Among all of those, the largemouth is the most popular. Of course, you probably knew that as an angler.

A lot of fishing resources go over different techniques and items you can use to catch a largemouth bass, but one core foundation of being a good angler is understanding its anatomy.

A largemouth bass is a living, breathing, organism, and while knowing the proper techniques is essential, understanding how a largemouth functions is crucial.

Because of that, we’ve set up this complete guide covering the largemouth bass anatomy; along with tips for how you can use this information to become a better angler.

Let’s get started.

Why is a Largemouth’s Anatomy Important?

If you can learn techniques proven to catch largemouth bass, why do you need to learn the ins and outs of its anatomy? Why is it a fundamental part of being an angler?

Well, there are actually two main reasons.

First, it helps with properly identifying the fish at the end of your line. As we said, there are a ton of bass species, and many of them look very similar at first glance. However, they behave very differently.

If we compare smallmouth vs largemouth bass, we find that a smallmouth is aggressive, but it won’t be nearly as strong or potentially as large as a largemouth.

Being able to identify what’s on the end of your line accurately isn’t just something to keep you from looking silly when you post your catch-all over social media. It helps you fight the fish and adjust your approach, too.

Then, there’s the fact that knowing how the fish works can help you find solutions to problems on the fly. You can know 400 different techniques, but unless you plan on cycling through those techniques one by one on every trip, you need to know how the fish goes about its life to understand what it is you need to do in any given situation.

For example, crawfish-red lures are extremely popular. Every tackle box should have a bag of them. However, they don’t work for much of the peak season because bass don’t start snacking on crawfish until they mature in the fall. This is why knowing what bass eat is crucial at times.

It also helps with optimizing certain bass fishing lures. For example, many topwater frogs slide right out of a largemouth’s gullet because it takes longer for the bass to snap its mouth shut and push the body of the frog out of the way. Knowing that many anglers bend the hooks inward or outward depending on the approach they’re going to take, and then they adjust their hook setting method to accommodate it.

So, it definitely comes down to a lot more than simply being able to look at the fish and identify it properly.

Basic Physical Anatomy of a Largemouth Bass

Learning the basic anatomy of a largemouth isn’t complicated. The telltale signs that make them stand out from other species are extremely easy to identify.

1: The Jaw of a Largemouth Bass

This is the trait that gives the largemouth its most defining features. So, we’ll cover it first.

The point where the jaws connect on a largemouth bass is well behind the eye. With other bass, that point is directly under the eye.

This isn’t just a minor anatomical difference, either. Because the jaw hinges further back, a largemouth can open its mouth a lot wider than any other bass out there. In terms of freshwater fish, it has one of the largest mouths in North America.

This means that you can use bigger baits, have an easier time unhooking the bass most of the time and dealing with foul hooks can be a lot easier for you and safer for the fish.

Not to mention, when a largemouth breaches the surface to swallow up a topwater bait, it’s quite the spectacle. It’s like a massive bucket opening up around your lure before it’s inhaled, and even the largest lures get swallowed right up.

That’s one way you can tell a largemouth is on the end of your line while it’s still in the water, too. Of course, that doesn’t help much when fishing lower in the water column.

2: Size

This is the second predominant feature that you can notice right off the bat. The size of the fish on the end of your line means a lot.

The most visually similar bass are smallmouth and spotted bass. Unless you get them up close, it can be difficult to notice the traits that set them apart from largemouth bass. However, you can instantly tell by the size of the fish in a lot of situations.

Largemouth are bigger fish. While a 21-pounder is unlikely, you’ll regularly catch 5 to 12-pound largemouth bass. With the other bass species, that’s like catching a state record in most cases. Most of your smallmouth and spotted bass catches are going to be less than 5 pounds.

So, if the bass has a large profile in the water, it’s likely a largemouth. Even if you get it wrong, a large profile with a smallmouth bass is going to be a good time, and you’ll probably want to weigh it.

Of course, this doesn’t always work. When you’re fishing right after a spawning period, you’ll catch tons of small largemouth bass, and that makes going off the size a bit more difficult. Even later in the season, you’ll occasionally pick up 2-pounders.

3: Coloring

This is one that changes depending on the conditions of the water, but it’s still reliable.

Smallmouth bass are dark green and sometimes have some greenish-brown in their coloring. The largemouth transitions from lighter colors on the bottom into forest-green backs. During the cold season, largemouth are lighter in color overall.

If the fish is really dark on its back when it’s starting to get close to the top, the likelihood of it not being a largemouth is fairly high unless other traits are noticed such as an abnormally large size or that tell-tale bucket mouth inhaling your lure.

4: Markings

You typically won’t need to look at a largemouth’s markings to identify it, but they can be useful when the bass is small.

Largemouth bass have a solid lateral line going down the middle of their bodies. Smallmouth bass have a dotted line with gradient markings, and spotted bass, as the name suggests, have dots. Other species tend to look different enough in general that marking comparisons aren’t needed.

If the bass weighs 14 pounds and its jaw is fully developed, this isn’t necessary, but you will catch yourself looking for markings right after the spawn.

Behavioral Traits of Largemouth Bass

Beyond the physical appearance of a largemouth bass, its behaviors are different, too. This largely plays into its anatomy and how its body allows it to do things differently than other bass species.

Here are some of the behavioral traits that are unique to largemouth bass and how you need to approach them differently because of these traits.

1: Blow-Ups

Smallmouth are technically more acrobatic, but largemouth bass definitely reign supreme when it comes to how dramatic their blow-ups are.

This has a lot to do with their larger stature and bucket-like mouths.

Smallmouth tend to get acrobatic after you have hooked them, and they make more frequent, smaller hops out of the water. When they blow up on lures without fully breaching the surface, it’s not nearly as dramatic.

When a largemouth breaches the surface, you’re in for a treat. They leap several feet out of the water, coil their bodies, and flare their gills as their bucket mouths open wide.

They truly look like the predators they are during these dramatic blow-ups. Even partial breaches where only their head leaves the water are dramatic due to their large mouths sucking in lures like a vacuum.

This difference requires you to change up your approach during the hook set and the fight.

With smallmouth bass, you have to focus on preventing the hook from getting spit out with back-to-back erratic leaps. Your hook set needs to be perfect, and you need to be ready to adjust your rod position quickly.

With largemouth, you only usually get one or two blow-ups during an intense fight. So, it’s not as nerve-racking when it comes to positioning yourself properly. However, each one is a lot more intense, and the chance of snapping your line is tremendous. So, you have to focus more on your line choice and make sure your drag tension is set appropriately.

2: Lure Spitting: Selecting the Right Hooks and Lure Sizes

Since largemouth bass have such massive jaws, you need to adapt your lure and hook selection quite a bit in comparison to other bass species.

In general, larger lures are going to be more enticing AND easier to set. With smaller options, the bass needs to really commit for you to get a good hook in its lip. It’s possible, but smaller lures do get spit out more frequently with average-sized bass.

Larger lures also tend to be more attractive due to their ability to look like a more substantial meal. The bigger the fish, the more food it’s going to want per feeding, and bass get pretty large.

3: Exploiting Predatory Traits

Everything about a largemouth bass screams “predator”, and that’s for a good reason. The largemouth bass is the apex predator in the vast majority of waterways in the United States. Outside of some fish like tarpon or invasive species such as snakeheads, largemouth bass are the dominant fish due to their stature and physical capabilities.

You can use that to improve your approach to catching them.

Largemouth don’t tend to hide or shy away from things. They’ll move around structures looking for baitfish, and they’ll swim directly into a large school of smaller fish without anything being able to stop them.

This helps you know where to look. If you see big schools of baitfish on your fish finder, it’s likely that a big bass is stalking them, and if you can make your lure blend in with that school of fish, your chances of catching a large bass increase dramatically.

It also helps you work on your presentation. Bass often approach from behind or beneath their prey. If bass is suspended in the middle of the column on a hot day, mimicking an injured fish just above the middle of the column can trigger those predatory instincts and move it into action.

Meanwhile, if the bass are at the top of the column, fishing deeper can prove to be fruitless. Attacking from above isn’t their usual approach, because it doesn’t work with their natural coloring. They’re more noticeable when looking up at them.

4: Tuning Your Gear to Match Their Strength

Due to their size and strength, largemouth bass are going to give you more problems than practically any other freshwater fish in the United States. They can snap lines with ease, rip lures in half, and start running with your line until you’re spooled out.

As such, you need to make sure you’re using the right bass fishing gear.

We’ve got entire guides on it, but in general, adjusting your drag, making sure you’re using sturdy types of fishing lines, and using rigs that minimize the chance of failure, are all crucial to effective bass fishing.

Catch More Bass with BassForecast

Learning about the largemouth bass anatomy is a good foundation to build your skill on, but that’s just it. It’s a foundation. You need far more specific information to really start capitalizing on that. That’s where BassForecast fishing app comes in.

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