The Softer Side of Sharks

Jim McMahon/Mapman®

Do sharks have friends? Culum Brown, a biologist in Australia, takes this question seriously. He believes sharks might be more than the scary predators many people believe them to be. Brown wants to know if sharks are social animals.

Brown has spent years studying how fish think and behave. In order to find out if sharks have a social side, he chose to study the Port Jackson shark in the waters around Jervis Bay, Australia. These 5-foot-long sharks live in waters around much of Australia’s coast. They’re numerous and easy for scientists to handle. “These guys are effectively like puppies,” Brown says.

Since 2006, Brown and his team have captured 300 Port Jackson sharks. They tag them with tracking devices and then release them. This work might sound difficult, but most of the time the sharks don’t even try to escape! Data from the trackers allows scientists to follow the sharks’ movements.

Do sharks have friends? Culum Brown takes this question seriously. He is a biologist in Australia. He believes sharks might be more than the scary predators many people believe them to be. Brown wants to know if sharks are social animals.

Brown has spent years studying how fish think. And how they behave. He wanted to find out if sharks have a social side. So he studied the Port Jackson shark in the waters around Jervis Bay, Australia. These 5-foot-long sharks live in waters around much of Australia’s coast. They’re numerous and easy for scientists to handle. “These guys are effectively like puppies,” Brown says.

Since 2006, Brown and his team have captured 300 Port Jackson sharks. They tag them with tracking devices. Then they release them. This work might sound difficult. But most of the time the sharks don’t even try to escape! Data from the trackers allows scientists to follow the sharks’ movements.

“We look to see who hangs with who, when, and where,” Brown explains. By noting where the sharks go and how many other sharks are present, his research team can learn how the sharks interact.

The tracked sharks keep returning to the same places year after year. Males and females of all ages come together. Instead of preferring to be alone, the sharks seem to enjoy the company of others.

“We look to see who hangs with who. And when, and where,” Brown explains. He notes where the sharks go. And how many other sharks are present. His research team uses this information to learn how the sharks interact .

The tracked sharks keep returning to the same places year after year. Males and females of all ages come together. They’re not alone. Instead, the sharks seem to enjoy the company of others.

Jeff Rotman Photography/Corbis via Getty Images

Culum Brown with one of his research subjects

Brown has made similar observations of Port Jackson sharks in captivity. In tanks in zoos, the sharks stay clustered together rather than moving far apart.

Brown’s research is just beginning. He suspects that other types of sharks will also show social behavior. By focusing on the easy-to-study Port Jackson sharks, Brown can perfect his research techniques. That way, he’s more likely to succeed when he tries to study sharks that are harder to handle or more difficult to find.

Brown hopes that learning how sharks socialize will help humans get along with them better too. “Sharks aren’t mindless people munchers,” Brown insists. In fact, some of them prefer to avoid humans and spend time with their fellow fish instead!

In tanks in zoos, Brown has made similar observations of Port Jackson sharks in captivity. The sharks stay clustered together rather than moving far apart.

Brown’s research is just beginning. He suspects that other types of sharks will also show social behavior. For now, he will continue to work with Port Jackson sharks. That’s because they are easy to study. This will help him succeed when he tries to study sharks that are harder to handle or more difficult to find.

Brown has hopes his work will help humans get along better with sharks too. “Sharks aren’t mindless people munchers,” Brown insists. In fact, some of them prefer to avoid humans. They would rather spend time with fellow fish instead!

One of the sharks that Brown tagged measured 66 inches in length.

This number is between which two tens?

On a separate sheet of paper, draw a number line between the two tens in your answer to part A. Indicate where 66 falls.

What is 66 rounded to the nearest ten?

Brown tagged 13 sharks in Jervis Bay in one month. He wanted to get a sample set of 30 sharks.

The next month, Brown tagged another 14 sharks. How many sharks did he tag in total in those 2 months?

What is this total rounded to the nearest 10?

Do you think Brown would want to use the rounded total or the actual total to determine if he had reached his desired sample size? Explain your reasoning on your separate sheet of paper.

As of last year, Brown’s team had tagged 288 sharks.

What is 288 rounded to the nearest hundred?

Brown has been tagging sharks for 10 years. Use your answer from part A to estimate how many sharks he tags per year.

Port Jackson sharks are easy to track because they live in shallow water, unlike many other sharks. Most are found in water that’s only about 330 feet deep. But some shark species live in water up to 902 feet deep.

Round both numbers to the nearest hundred.

Use your answer from part A to estimate how many times larger 902 is than 330.

Brown’s lab has an adopt-a-shark program to help fund research efforts. For $500, participants sponsor a tracker and can follow a shark’s movements.

Let’s say 13 classmates decide to adopt a shark together. They each contribute $38. Student A rounds 38 to the nearest ten, and then finds the total amount donated using the rounded number. He says the group has $20 extra. Student B finds the total amount donated and tells the group that they’re $6 short of their $500 goal.

Brown’s lab has an adopt-a-shark program to help fund research efforts. For $500, participants sponsor a tracker and can follow a shark’s movements.

Let’s say 13 classmates decide to adopt a shark together. They each contribute $38. Student A rounds 38 to the nearest ten, and then finds the total amount donated using the rounded number. He says the group has $20 extra. Student B finds the total amount donated and tells the group that they’re $6 short of their $500 goal.