Salt, Fresh and the Journey Up: teacher key

Bull Sharks, grade 11 edition, written for 11th grade. How can a shark of the sea live in a river? Read how a bull shark manages salt, and how far young ones go.

Read the book. Print this page for the key.

Questions and answers

1. What does a bull shark lower to cope with fresh water?
   • Its teeth
   • Its tail
   • Its urea (answer)
2. What did young sharks in the laboratory study do when moved into sea water?
   • Stopped swimming
   • Quickly raised the concentration of their blood (answer)
   • Lost their colour
3. Where have bull sharks been reported more than 2,000 miles upriver?
   • The Amazon River, in Peru (answer)
   • The Thames
   • Lake Erie
4. Why can a bull shark live in so many places?
   • It never sleeps
   • It is very big
   • It can manage the salt in its body (answer)
5. What does brackish mean in this book?
   • Very deep
   • Slightly salty (answer)
   • Very cold

Words

• brackish: slightly salty
• salinity: saltiness
• urea: body waste