The teeth in the back of the jaw are also different, being less symmetrical and smaller.
All sharks are not nasty predators, and thus many sharks, and their close relatives, have very reduced teeth or teeth modified into crushing plates. The sharks that most people think of when they hear the word shark are known, at least in my world, as Sharky-sharks. The non-sharky-sharks are not likely to take a bite of out you.
Crushing plates are found in the horn sharks and eagle rays, for example, while tiny teeth are found in the filters feeders; the Basking Shark, Whale Shark, and Megamouth Shark. While a large Great White Shark has many teeth with some larger than 4 cm, these species also have huge numbers of teeth but they are tiny; the Whale Shark can have 300+ rows of tiny 5 mm teeth (get out the microscope) for a grand total of 3000 teeth. The Basking Shark has similarly sized teeth with a few rows of teeth near the front of the jaw and many more rows behind. The Megamouth, again, has similarly sized teeth with 50 (upper jaw) to 75 (lower jaw) rows of these tiny teeth.
The Spiny Dogfish, Squalus acanthias, has even smaller teeth (it's also a much smaller shark) than the Whale Shark and Basking Shark but they are sharp, whereas the teeth of these giants are blunted.
Oddest teeth; Cookie cutter shark
The cookie cutter shark has large teeth in its lower jaw, shaped much like the Great White, and pointed and smaller upper jaw teeth. These little buggers can take chunks of flesh out of prey— like a cookie cutter has been punched through the tissue. The teeth of the lower jaw appear too large for the shark (the shark can reach about 1/2 a meter in length but are more common smaller; hold on one second, these sharks are never common).
Some sharky-sharks have cusps on their teeth - the porbeagle and Sand Tiger are good examples of this feature: mostly they are fish eaters, easier to grab and hold their dinner. Many shark teeth have small serrations, which probably work toward the same function.
At least for the predatory species shark teeth grow and are replaced throughout their lives. How many in a lifetime – I can’t find an analysis of this except on blogs (for example from the Sharkwatch SA Blog, Michelle Wcisel estimated the Great White Shark goes through over 29, 000 teeth in a lifetime; the formula used was rate of tooth loss x average lifespan of shark (30 years) = teeth over a lifetime). She estimate the rate of tooth loss at 19 per week (988 a year), which seems very high to me but what do I know. This value, about 30,000 teeth in a lifetime, was the same number I heard from a sea world educator the last time I was there, but, there seems to be no actual data on the subject.
Do species that are not nasty predators lose teeth, and grow many teeth throughout their lives. I’m still searching for information On this.
Shark heads: Get to work, many questions, lots to be done. And noooooo way am I doing it, I’m not looking in any more shark mouths. The last time Matt told me to do that I came away with a nasty cut.
Further Reading
Into sharks? Check out Amanda Flannery’s blog on sharks 🦈
https://oceanforsharks.wordpress.com/author/dundunt/
Shark Watch Blog:
http://www.sharkwatchsa.com/en/blog/