The Tooth of the Matter
Dive into the world of shark teeth with a few residents here at the Aquarium.
- Animals
Whether you were swimming over a coral reef or trembling under the covers watching "Jaws," your first experience seeing a shark might have felt slightly unsettling. From their muscular bodies to their pointed teeth, sharks have gotten a bad rap over the years as being dangerous, killing machines. While this couldn't be further from the truth, a shark's teeth are incredibly important in how and what they eat, from crustaceans on the seafloor to rays to even smaller sharks. Read on to learn more about a few resident shark species in our Shark Alley exhibit and how the shape of their teeth are adapted to where they live and how they survive.
Sand Tiger Shark
Sand tiger sharks are a large, migratory species that travel up and down the coastal waters of the Eastern United States. They might have an intimidating appearance, with a mouthful of narrow, pointed teeth, but they're not aggressive towards humans unless provoked. These teeth are specialized to spear fast-moving prey, including fish and smaller sharks, before often swallowing their meal whole.
During the summer, sand tiger sharks congregate in the Delaware Bay and coastal areas of the northeastern United States in search of prey, returning to more southern waters as winter arrives. Unlike other sharks, they are unique in their ability to gulp or burp air to regulate their buoyancy.
Sandbar Shark
The sandbar shark is a common summer resident in the lower Chesapeake and Delaware Bays which serve as two of the most important nursery grounds for this species in the northwest Atlantic. Females give birth to between one and 14 pups per litter every two to three years.
These sharks have broad, triangular, sharp teeth with serrated edges for tearing apart their prey. As opportunistic feeders, they have to ability to feed on a wide variety of prey items, from bony fishes to octopuses to crabs. Like the sand tiger sharks, sandbar sharks are seasonal migrators, heading north as warm weather returns.
Nurse Shark
Nurse sharks are generally slow and sluggish, spending much of their time on the ocean floor. These bottom dwellers breathe using a process called buccal pumping, where they pull oxygenated water through their mouths and over their gills, all while remaining still. These sharks might be seen resting together during the day, but are solitary, nocturnal hunters.
Nurse sharks find most of their prey on the ocean floor, including clams and crustaceans. A cavity within their throats creates powerful suction power, pulling animals from the benthic habitat into the shark's mouth, where rows of short, serrated teeth can crush hard shells, urchin spines or bony fishes.
What are dermal denticles?
Sharks can lose upwards of 30,000 teeth in a lifetime, but did you know that their skin is made of toothlike structures as well? Placoid scales, also known as dermal denticles, are similar in structure to a typical tooth, and have nerves, blood vessels, and a coating of enamel. The benefit of these unique structures is reduced drag while swimming and protection from injury or parasites. Like their actual teeth, these scales are regenerated throughout their lives.
Save our Sharks
Sharks have been around for over 400 million years and are currently represented by about 520 species, but they're in trouble. Many shark populations have declined by more than 90% due to overfishing, climate change and habitat loss. While a shark-free sea might sound safe for swimming, sharks are critical in keeping delicate ocean ecosystems in balance by maintaining food webs as top predators and scavengers. Fear of sharks has resulted in mass killings of sharks and general anxiety over shark bites, but these incidents are still incredibly rare. By protecting the sharks that remain, we are protecting the ecosystems on which many other species, including humans, depend.