Thursday, January 6, 2011

Tale of the Teeth

Northern on the fly
Back to some science once again!  Aren’t you guys all excited about that?  

I want to talk about the tale of the teeth now. I love to fish for toothy predators. Probably my favorite fish to target on a fly are those with some serious dentition- northern pike, muskellunge, bowfin, and gar all come to mind. What is pretty astonishing though is that many fish we angle for do have teeth whether we know it or not. Bass and trout do indeed have teeth. I will get to that later.

Needle sharp teeth
So what do teeth tell us about a fish and how does that relate to fly fishing?  A great deal really on both ends of that question. Probably the most important thing that dentition tells us is what the fish preys on. I will go back to my old friend the longnose gar. Gar have a single row of tiny needle like teeth on either side of their mouth (which is really just elongated bone). When a gar feeds it makes a slashing strike from the side. Combine the length of the mouth with those needle sharp teeth and you have a great means of grabbing baitfish. A look at other fishes and other animals around the world shows this mechanism to be a fairly common form of eating smaller fish. Houndfish, needlefish, needlenose gar (Xenentodon cancila), Belonesox (the pike livebearer) and others show convergent evolution of this baitfish munching apparatus. I pointed out in an earlier post that gharial and false gharial (both crocodilians) also share a similar mouth structure to allow them to easily grab their prey.

Drum pharyngeal teeth
Crawdad munchin' drum
Let’s look at another fish that has some pretty cool teeth that you probably didn’t even know had teeth- the freshwater drum. This fish’s teeth are found past its mouth. They are called pharyngeal teeth and are located near the fish’s gills. These teeth are nothing like the typical teeth you might think of when you are thinking of fish teeth. They are not sharp. They aren’t for grabbing or slashing or cutting pieces of prey. They are used for crushing. They look like blunt round topped cylinders. When the drum eats a crayfish or a mussel it will bring that food item back to the pharyngeal arch to crush it up. Great adaptation for dealing with crunch food huh? Works really well too. It has helped the drum to adapt to a new prey item in Lake Champlain, the zebra mussel, very quickly. Within the past 15 years the drum in Champlain has used their pharyngeal teeth to great advantage with this nuisance species and the zebra mussel now comprises about two thirds of their diet.

So what do these two examples have to do with tossing feathers?  Well, with the gar I use a wire leader because of their teeth. I probably could get away with using just hard monofilament because the teeth aren’t really cutting teeth, but the wire works well. Do I use a special leader system with the drum? Nope. No need.

Can't see them but there are some teeth below the fly
Wire or hard mono or fluorocarbon does make a huge difference when targeting a lot of different toothy fish. In my book anyone who is not using any of these systems when fishing for pike is a total idiot (I can think of a guide in Vermont who fits in this category quite nicely and you know who you are… idiot). Little do many of us realize that the classic fly rod fish, the brown trout, has some pretty serious teeth. Anyone who has made the mistake of lipping a brown like you might do with a bass has found that out the hard way. I remember those nice parallel lines in my thumb after pulling off that maneuver. Those vomerine teeth are nice and sharp. It is a very effective way of holding onto your prey. Ever caught a smaller trout that has tooth marks on it? I definitely have. Makes you wonder if a pike got into the trout stream sometimes… it probably was one of those big predatory browns that lurks in the hearts and minds of all stream fishermen everywhere. Those of you who don’t target warm water fish are angling for a toothy predator after all. And no wire needed too!

Look at the teeth on that bass-turd!
Ya gots some algae for me?
How about bass? They don’t have teeth do they? Well yes they do. Again, not the classic teeth you think of, but indeed lots of teeth. They are really small teeth and act more like sandpaper. Ever wondered what happened to your thumb after a day of hammering smallies? I bet it looked pretty chewed up. And it was!  If you were to use a magnifying glass to look at the edges of a bass’s mouth on the top and bottom you would find a bunch of little teeth that the fish uses to get a better hold on their prey. Pretty cool. This is not an unusual adaptation for fish to have. Some cichlids in the African rift lakes have taken this to the extreme. They have fleshy lips loaded with teeth similar to the bass, but more on the outside of their mouth. Those teeth are used to rasp algae off rocks. When you are in a very competitive environment like Lake Tanganyika and are a member of a very rapidly reproducing fish family, it won’t take much time for you to evolve into a form that will allow you to utilize an abundant food source like filamentous algae.

How about some of my favorite fish- pike and musky? These guys have teeth baby! Lots of teeth. The muskellunge has over 450 teeth in the upper jaw alone. Check those choppers out! Some serious canine teeth coming up out of the lower jaw don’t you think? What a great way to impale a prey item to keep it in your mouth. Then look at the upper jaw. Most of those teeth are facing backward. This is a very effective way of preventing your prey from getting away. What goes in can’t come out, at least not very easily. Keep this in mind if a pike or musky clamps down on your hand. Try to resist yanking it back out because you will cause yourself a lot more damage.

Pike below, musky on top
Look at those canines!
Are the teeth of these fish the same? Nope. Compare the skulls. The musky has slightly longer/bigger canines. A close look at the smaller teeth in the upper jaw exemplifies another difference. The musky has some bigger teeth at different angles interspersed with those smaller rear facing teeth. Why is this? Well, the musky is a larger predator and will typically target bigger prey items. A big musky will eat things like muskrats, ducks, and turtles with surprising regularity. Those bigger teeth with help this fish handle that kind of victim a bit easier. Yea, pike will eat those too, but generally you will find that the musky is more likely to. Classic apex predator- kill and eat whatever you can fit into your mouth! And that mouth gets big! No wonder muskies occasionally bite swimmers!

Getting to know fish teeth will help you understand your angling quarry a lot better. Knowing the tale of the teeth helps you understand what a fish eats. When you know what a fish eats you will be able to replicate that fish’s prey with an appropriate fly much more effectively. Ultimately it will help you prepare for situations that you may find yourself in while targeting them. That means you should catch more fish. Do your homework! (don’t you feel like you are back in school?)

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