Sharks can be found in every ocean around the world! From warm tropical waters to the chilly polar regions. Tropical regions are home to Shark species like the Great White Shark (Carcharodon carcharias) found in the warm waters of the Pacific and Atlantic Oceans. In the polar regions, where temperatures are frigid, the Greenland Shark (Somniosus microcephalus), has unique adaptations that allow them to survive in the extreme cold. Sharks can thrive in a wide range of temperature environments, from the tropical heat to the freezing cold of the polar regions. Their ability to live in various temperature zones is part of why they are so important in the world’s oceans.
What are Sharks?
Shark bones are all made of cartilage! A strong and flexible material found in our ears and noses. Cartilage is lighter than bone and helps sharks to move in water. Shark skin feels rough like a cat’s tongue, because of dermal denticles, which are tiny teeth facing backwards that help Sharks move swiftly through the water. Some Sharks are born with a complete set of teeth that they continuously replace throughout their lives, with some species shedding up to 30,000 teeth. Other Sharks do not have any teeth and instead filter feed, like Whale sharks. Sharks also have a sixth sense, called “‘amupllae of lorenzini” on their snout, which can sense electrical fields emitted by surrounding animals. This helps them hunt. Shark fins help with stability and balance while swimming. Each Shark species has a distinct fin shape; fast-swimming sharks typically possess short, crescent-shaped tails, while slower-moving sharks exhibit longer and thinner tails. Since Sharks are fish, they breathe through gills located on the sides of their heads. To extract oxygen from the water, Sharks must constantly move (even when they sleep!), allowing water to flow through their mouths and over their gills. Some bottom-dwelling Sharks can suck water into their mouths and push it through their gills, even while resting.
Because there are so many kinds of Sharks, Shark behavior changes depending on the species, and since Sharks spend their entire lives in the ocean, scientists still have much to learn about Shark behavior. Sharks are mostly solitary (meaning they live by themselves), and rarely gather together but some Shark species, like the Hammerhead, form social groups called “schools”. Sharks tend to be most active during dusk and like to hunt at night. Although they are Apex predators, they still tend to be cautious when hunting, and rely on sneaky tactics to surprise prey. Because hunting also takes a lot of energy, it is common that large sharks like Great Whites only eat a few times a week. Just like other animals, Sharks also have specific migration patterns which vary from species to species. These migration patterns are due to temperature changes throughout the year, and prey migration.
Because there are so many different kinds of Sharks, they have a lot of different diets. Some Sharks, like the Great White shark, are Apex predators and feed primarily on other marine animals such as seals, sea lions, and smaller Sharks. Others, like the Basking Shark, are filter feeders, eating plankton and small organisms by filtering them through their gill rakers. The Whale Shark, the largest fish in the world, is also a filter feeder, feeding on Plankton using its enormous mouth. Sharks like the Tiger Shark and Bull Shark are opportunistic feeders eat many different things including fish, squid, turtles, and sea birds. Some species, such as the Nurse Shark, feed on bottom-dwelling organisms like crustaceans and mollusks. From specialized hunters to filter feeders and scavengers, the diverse diets of Sharks highlight their vital role in maintaining the balance of marine ecosystems.
Shark birth can be very different depending on the species. Most Sharks have what is called a “live birth”, and resembles how mammal embryos, including humans, develop inside of the mother. Other Sharks lays egg cases, which later hatch outside of the mother’s body. And some Shark species have eggs that remain inside the mother’s body until they hatch. Shark babies, called pups, never stay with the mother, and are entirely independent when they are born. Shark pups usually stay within shallow areas close to the shore and rivers, called estuaries, until they can venture into the open ocean. The number of pups born from each litter can be anywhere from 1 to 300. Typically, the gestation periods can change greatly as well. Some have a gestation period of 5 months, while others can last up to 3 years!
Sharks face numerous threats in the wild. Firstly, overfishing and finning have resulted in drastic declines in Shark populations worldwide. Habitat loss due to coastal development and pollution further disrupt their ecosystems. Climate change impacts the oceans, affecting shark habitats and altering their prey availability. Bycatch, the accidental capture of Sharks in fishing gear, also poses a grave threat.
As top predators, Sharks help keep the ocean balanced. They eat other animals, which helps control their populations. Sharks also play a role in protecting coral reefs by keeping the numbers of harmful predators in check. They even help prevent the spread of diseases among marine animals. Sharks are so important for keeping the ocean ecosystem in top shape.
Some Sharks continue to face significant challenges from overfishing and habitat destruction. Many species are listed as vulnerable, endangered, or critically endangered. But conservation efforts have shown promise in certain regions, leading to small population recoveries for some Shark species. Additionally, public awareness and advocacy have raised concerns about Shark finning, leading to increased regulations and bans on Shark fin trade in several countries. Despite these positive steps, continued monitoring and conservation actions are crucial to ensure the long-term survival and recovery of Shark populations. It is important for us to work together to protect and preserve these magnificent creatures and their vital role in maintaining healthy marine ecosystems.
How to Help
Sharks need our help! You can help by, supporting sustainable fishing practices. Choose seafood options that are caught using sustainable methods and avoid consuming Shark products or dishes that contain shark fins. Reducing pollution. Avoid littering and use eco-friendly products and practices. Pollution can harm Sharks directly and destroy their habitats. Be aware of protected ocean habitats. Spaces like estuaries are typically protected for animals. Make sure to help keep them safe for animals leaving them be and avoid walking in them or picking up marine life. Spread awareness. Educate others about the importance of Sharks in marine ecosystems! The more people understand Sharks and their vital role, the more support they will have for conservation efforts.