Hard vs. Soft Bites: What’s the difference and why do bass use both? By fish biologist Noah Bressman
Nothing is more satisfying than when you’re slowly twitching topwaters near the edge of some weeds and a monster bass explodes on your frog (a close second being when fat spotted bass slams your bait near the boat, just as you are about to take it out of the water). A lot of times when you slowly work soft plastics, though, bass don’t hit them hard, and you may barely be able to feel a strike (if at all). These “soft” and “hard” bites that bass use are actually two different feeding behaviors. During hard bites, bass feed using a behavior known as ram-feeding, which is what it sounds like: the bass swims with its mouth open and rams its prey. During ram feeding, as seen in this video of a barracuda: https://www.youtube.com/watch?v=6emvb4QHGiU the key is body speed and power. The faster and harder a bass rams its prey, the more successful it will be. Bass are alright at ram feeding, but since they don’t have sharp teeth to impale prey and cannot swim as fast as barracuda, they often rely on a second type of feeding.
When bass use a soft bite, they often use a feeding behavior known as suction feeding. In suction feeding, a fish will rapidly open its mouth and expand its oral cavity (also known as the buccal cavity), which causes water to rush in. According to Dr. Peter Wainwright, professor of Biology at the University of California, Davis, “bass suck in 2-3 times the volume of their buccal cavity of water during a [suction feeding] strike (Higham et al., 2006).” While sucking in a large volume of water, they suck in any prey within that volume of water, capturing the prey before they even touch it. In this video from Dr. Wainwright’s lab https://www.youtube.com/watch?v=OHivHHmYSDc, a largemouth bass can be seen suction feeding with a technique known as particle image velocimetry (PIV). Basically, PIV involves a lot of particles in the water so that you can see the flow of water. This technique allows you to see that when the bass opens its mouth, it is able to suck in a lot of water, along with its prey from a short distance. This allows bass to stealthily ambush prey from weeds or other structures. Additionally, as Dr. Wainwright explains, these strikes can happen extremely quickly, with prey capture sometimes occurring in less than 4 milliseconds! Since bass are so remarkable at suction feeding, they are often used as model organisms for suction feeding research. Dr. Elizabeth Brainerd, professor of biology at Brown University, uses largemouth bass to study how the different bones in the head move during suction feeding using a technique called X-ray Reconstruction of Moving Morphology (XROMM). Basically, this technique involves using x-ray videos to show how bones move in relation to each other during a behavior. In this video of a bass suction feeding (https://www.youtube.com/watch?time_continue=1&v=CRRUH01HLLY), it is clear to see how the bones in the head move to expand the oral cavity, greatly increasing the volume in the mouth.
What does this mean for bass fishing? To put this in perspective, last weekend, my buddy Shem and I fished at Salem Lake in North Carolina and experienced the difference between hard and soft bites. Shem was using a topwater frog and I was using a wacky-rigged Yamamoto Senko. We both got some good bass (mine were bigger), but the fish hit very differently for each of us. For the topwater frog, there was no mistaking when a bass hit; it would slam the frog at the surface and make a big splash. However, ram-feeding can be somewhat imprecise, and Shem’s strikes often missed the hook. When the bass hit my Senko, they hit more gently. Using suction feeding, one quietly inhaled my bait whole, without me even noticing. I only noticed the fish on my line when the line started moving towards me. I may not have noticed the hits as well as with the frog, but because the bass sucked my baits in whole, they had a better chance of being hooked well. So it’s a trade-off: fast-moving lures that elicit ram-feedings strikes may have more noticeable bites, but are less likely to get the hook, while slow moving lures that elicit suction-feeding strikes may be have less noticeable bites, but are more likely to get a solid hookset. While neither method isn’t necessarily better, it is important to be mindful of how bass hit different lures in different ways.
Higham, T. E., Day, S. W., & Wainwright, P. C. (2006). Multidimensional analysis of suction feeding performance in fishes: fluid speed, acceleration, strike accuracy and the ingested volume of water. Journal of Experimental Biology, 209(14), 2713-2725.
Noah Bressman is a PhD student studying fish biology, functional morphology, and biomechanics at Wake Forest University. Above is Noah with a Largemouth Bass (Micropterus salmoides), caught at Salem Lake, NC on a weightless, wacky-rigged silver glitter Gary Yamamoto Senko.