Directions: After students read the article “Hermit crabs are drawn to the dead,” have them answer the questions below.
1. How do hermit crabs get their homes?
Hermit crabs can’t grow their own shells. Instead, the crabs take over shells originally occupied by snails that have died.
2. How do hermit crabs “remodel” their shells? What are the effects of this remodeling?
Growing hermit crabs can use corrosive secretions and scraping to make their shells bigger. Remodeling can widen a shell’s opening, remove the internal spiral and reduce wall thickness.
3. What hermit crab behavior did biologist Mark Laidre and graduate student Leah Valdes observe on the beach, and what conclusion did they draw from those observations?
Dozens of land-dwelling crabs swarmed tubes containing bits of hermit crab flesh, the researchers found. The hermit crabs appear to be drawn to the scent of flesh of their own kind.
4. Apart from land-dwelling hermit crabs, what other animals were included in the study? What did the researchers find based on their comparisons?
The team compared land- and sea-dwelling hermit crabs’ attraction to the scent of other dead hermit crabs and to the scent of dead snails. Land hermit crabs were attracted to both scents, but found the hermit crab corpses more alluring. Sea hermit crabs, however, did not find the scent of hermit crab flesh more appealing than the scent of snail flesh.
5. Why might land hermit crabs have developed a strong attraction to the scents of other dead hermit crabs?
The scent of death may signal to land hermit crabs that a bigger home is available and will be relatively easy for them to move into. Moving into an already remodeled shell left behind by another hermit crab may be easier than remodeling their own shell or a new snail’s shell.
6. What two factors make finding a new shell challenging for land hermit crabs as compared with sea hermit crabs? Explain how each factor presents a challenge for crabs.
Both land and sea hermit crabs need shells that are just the right size — big enough to grow into but not too heavy in the short term. Land hermit crabs face tougher competition because there are fewer empty shells available on land and the land-dwellers don’t have water’s buoyancy to help them hold up a heavy shell. Sea hermit crabs benefit from the fact that shells can float and so can move into shells that might otherwise be too heavy for them on land.
7. Why does ecologist Chia-Hsuan Hsu say people shouldn’t take shells from the beach?
When people take shells from beaches, they are taking away potential homes for land hermit crabs.
8. After reading the article, name one literary device that the author uses to grab readers’ attention and explain how it relates to the story.
The author uses a metaphor at the beginning of the article. He compares land-dwelling hermit crabs to a millionaire with no heirs. When a land-dwelling hermit crab dies, it leaves behind an empty shell that is incredibly valuable. The dead hermit crab’s scent attracts other hermit crabs looking for a new home, just like a dead millionaire’s money attracts people that want a piece of the fortune.