Tag Archives: Shark

Shark Teeth 101

While shark teeth have long adorned the necklaces of ocean-inclined Homo sapiens, the true purpose of these aggressive dentures is all about getting food. However, being that there are over 400 species of sharks, one shark’s idea of a good meal might be very different from that of another species. Different shark species can have dramatically different teeth that reflect their dramatically different diets. The horn shark, a local bottom dweller that feasts upon bivalves, urchins, and crustaceans, has small flat teeth with which it crushes the hard-shells and exoskeletons of its prey. Meanwhile, the blue shark, a pelagic species that prefers squid and fish, captures its prey by piercing it with knife-like teeth. The list goes on and on: tiger sharks have serrated teeth for ripping the flesh of seals and other large prey, while whale sharks have reduced teeth that they don’t even use, as they eat plankton that they filter through their gills.

Shark teeth

http://www.fancynancypantsinct.blogspot.com

Though shark teeth vary depending on the species, they all have one thing in common: they get lost… a lot. Shark teeth aren’t rooted into gums like human teeth, and so are much more prone to falling out when prey puts up a fight. For a shark though, loosing a teeth is no big deal. Unlike humans, which only go through two sets of teeth in a lifetime, sharks have no such limits and are continuously replacing their teeth. A single shark can loose thousands of teeth in its lifetime! Clearly, the shark tooth fairy is a far busier individual than the being that looks under our pillows.

shark teeth wow

Caption: A blue shark showing off his piercing, knife like teeth!

http://www.sciencemag.org/news/2012/08/scienceshot-human-teeth-hard-shark-teeth

This continuous replacement of teeth is only possible because sharks, behind their teeth, have more teeth, and behind those teeth, are more teeth, and behind those teeth, are even more teeth, and behind those teeth… you get the idea. These backup teeth are arranged in multiple rows inside of a sharks mouth and work like a vending machine to push new teeth forward whenever the need arises. Depending on the species, a shark can have 5 to 15 to even 50 rows of teeth in each jaw. That’s quite the mouthful!

shark teeth horn

Caption: A horn shark displaying her small, dense teeth used for crushing!

https://www.pinterest.com/pin/196188127488284437/

Sharks are some of the ocean’s most successful predators, thanks in large part to their phenomenal teeth. The next time you’re around some shark teeth, whether sporting jewelry, sifting through a beach, or snorkeling with a living shark, remember that there’s much more behind each tooth than meets the eye.

Sources:

https://www.worldwildlife.org/species/shark

http://beachchairscientist.com/2012/08/12/sink-your-teeth-into-this-20-facts-about-shark-teeth/

 

The Elusive Leopard Shark

On beautiful, clear days here on Catalina Island, taking a stroll down the pier is the perfect way to spot our elusive friend, the leopard shark! These shy guys love to hang out in Catalina’s shallow coves and search the sand for benthic, or bottom dwelling critters like crabs, shrimp, and rockfish. If you’ve visited CIMI before, than you may have been lucky enough to have spotted one of these striped guys from the pier, or maybe even caught a glimpse on a snorkel!

Leopard sharks

Leopard sharks have long fascinated us with their mysterious behavior; Just as fast as they congregate in our coves, they are gone hours later. It is hard to know precisely when we will see them gliding under the pier, however they usually enjoy cruising just outside the surf zone during the day, and move to deeper waters at night. They move with quiet agility, but are spooked easily and don’t much enjoy human swimming companions. This shy behavior makes them a very non-threatening species to us, as they have never been known to act aggressively.

Screen Shot 2016-01-30 at 11.27.44 AM

Leopard sharks inhabit the shallow waters of the North Pacific, ranging from Oregon to Mexico. These sharks don’t usually travel far, which has caused genetic diversity to occur within the isolated populations. Some populations grow bigger than the average mature size of about 4 feet, and others produce less offspring than the average. They don’t really like water temperatures that drop below about 50 degrees Fahrenheit, and one study recorded a tagged individual traveling about 87 miles south to escape the colder Northern California waters. Talk about cold feet, or fins in this case!

leopard shark range

Leopard sharks are viviparous, which is a fancy way of saying they give live birth. Leopard moms like to give birth in very shallow areas, sometimes as shallow as 3 feet, where their dorsal fins might even be exposed. They give birth to anywhere from 7 to 37 pups, which will remain in even shallower areas for their early lives.

These patterned beauties are quite the sight to see in the water, but since they enjoy shallow areas, they are vulnerable to human pollution. They get themselves into trouble when they swim around warm water outputs coming from power plants. Leopard sharks are exposed to pesticides and other harmful runoff from agricultural areas, due to the nature of their shallow environments. They are also susceptible to being caught in gillnets, long lines, and other commercial fishing devices.

leopard shark kelp

Luckily, these guys are listed as an animal of least concern by the International Union for Conservation of Nature, which means their populations are at a healthy number. They are especially abundant here on Catalina, but we must continue to take the proper steps to protect them, because they could easily become threatened in the future. Let’s do our part to keep pollution out of the ocean, and to advocate for the preservation of these pretty creatures so we can continue to enjoy their beauty for years to come!

CIMI Mythbusters: Megalodon

Megalodon, meaning “big tooth”, was a HUGE shark that lived about 16 million years ago. It is thought to be the largest shark to ever exist. Megalodon grew up to 55 feet in length and weighed around 100,000 pounds, compared to a modern great white shark at 22 feet and 4,000 pounds. The teeth found from this shark have been between 5 and 7 inches! The jaw of the megalodon were 7.5 feet tall and 8.5 feet wide, so an adult could stand inside them and have plenty of room left over. Although it would be amazing to see a megalodon in person, unfortunately they have been extinct for about 2.6 million years.

This was a widely accepted fact until the Discovery Channel presented a “mockumentary” in its shark week program titled “Megalodon – The Monster Shark Lives.” Despite a short disclaimer at the end stating that the entire piece was fabricated, it managed to convince 70% of viewers that megalodons exist in waters today. Though it is very difficult to prove that something doesn’t exist, there is absolutely zero evidence pointing to their current existence, and information presented in the mockumentary was completely made up.

Let’s discuss Megalodon alive or extinct. First, the scientists speaking about megalodon are all actors. One of the marine biology experts and shark consultants for “Megalodon – The Monster Shark Lives,” is actually an actor named Darron Meyer, who also played a doctor in the Free Willy sequel movie. The World War II photo, showing a dorsal to caudal fin spanning 64 feet, was doctored. Megalodon fossils only show the sharks at lengths up to 55 feet, and this photo claims a 64-foot span just from dorsal fin to tail!

Though there have been recent discoveries of animals previously thought extinct, such as the coelocanth or megamouth shark, both live in places hard to detect. The coelocanth lives in caves up to 500 meters (1650 ft) deep during the daytime. Though around 15 feet in length, the megamouth shark lives at depths of 120-160 meters (400-525 feet) during the day. Megamouth sharks also feed on plankton, so there would be no bite mark evidence on other animals, which is how scientists discovered the giant squid without ever seeing one. This makes both the coelocanth and megamouth very difficult to detect, leading to their recent discovery.

The megalodon did not live at great depths, and definitely didn’t eat plankton! Fossil evidence indicates that they preferred shallower, warmer waters because of their need for large prey. A megalodon needed about 2,000 pounds of food per day! They were not adapted for life in the deep sea, nor would there be enough food to sustain them. Therefore, they could not currently live deep enough to avoid detection.

If somehow they did avoid detection by living in the deep sea, their prey consisted of mostly large whales. Much like the giant squid attacking sperm whales, scientists would find large sharks and whales with bite marks too big to be attributed to a modern species.

Finally, there are no discovered megalodon teeth that were shed recently. It is possible to find megalodon teeth throughout North America, in places like South Carolina, Maryland, North Carolina and Florida. None of the teeth found have been recently shed. Sharks have rows of teeth and can easily replace a tooth lost in hunting. The megalodon had 46 teeth in the front row. It is estimated that great whites can go through about 50,000 teeth in their lifetime. If each megalodon was currently shedding that many teeth in one lifetime, it is very unlikely that none would be found.

Official Answer from CIMI Mythbusters: Busted

WECOME TO THE CIMI BLOG

We would like to thank you for visiting our blog. Catalina Island Marine Institute is a hands-on marine science program with an emphasis on ocean exploration. Our classes and activities are designed to inspire students toward future success in their academic and personal pursuits. This blog is intended to provide you with up-to-date news and information about our camp programs, as well as current science and ocean happenings. This blog has been created by our staff who have at least a Bachelors Degree usually in marine science or related subjects. We encourage you to also follow us on Facebook, Instagram, Google+, Twitter, and Vine to see even more of our interesting science and ocean information. Feel free to leave comments, questions, or share our blog with others. Please visit www.cimi.org for additional information. Happy Reading!

Categories

Tags