A Head With Many Theories: teacher key

Hammerhead Sharks, grade 11 edition, written for 11th grade. Scientists have disagreed about a hammerhead's eyes, and they have proposed several ideas for why its head is so wide. A tagged great hammerhead migrated from the Bahamas to South Carolina.

Read the book. Print this page for the key.

Questions and answers

1. What did some scientists once suggest about hammerhead eyes?
   • That their visual fields could not overlap (answer)
   • That they cannot see color
   • That they are closed at night
2. What did others argue about the wide spacing of the eyes?
   • It hides the shark from prey
   • It improves binocular vision (answer)
   • It blocks the shark's smell
3. Why is there a larger blind area just in front of a hammerhead's snout?
   • Its eyes are widely spaced (answer)
   • Its nostrils are closed
   • Its head is nearly straight
4. Where did one tagged great hammerhead migrate from and to?
   • From Brazil to Australia
   • From the Bahamas to South Carolina (answer)
   • From Florida to the Bahamas
5. What do electroreceptors help a scalloped hammerhead do?
   • Detect buried prey and navigate (answer)
   • Chew its food
   • Stay warm

Words

• electroreceptors: electric sensors
• biologgers: tracking instruments
• maneuverability: turning skill
• binocular: using both eyes
• nostrils: smelling openings
• hypothesized: suggested