Questions for “A sea slug’s head can crawl around and grow a whole new body”

sea slug body next to detached head

The detached head of a sea slug (Elysia cf. marginata) glides by its still-living, leaf-shaped body a day after separation. That body, around 80 percent of the animal’s weight, is out of luck. It’s the head that survives, growing a new body.

S. Mitoh

To accompany “A sea slug’s head can crawl around and grow a whole new body


Before Reading:

1.  Some animals can grow new body parts after they lose an old one. Name two that you’ve heard of that can do this. What parts can they regrow?

2.  What is a parasite? Give at least one example. (Hint: Several well-known examples can infest the human body.)

During Reading:

1.  How does a rippling, green-tinged sea slug find itself without a body? How long does it take to get a new one?

2.  What are planarians and how do they differ from these sea slugs in their ability to regrow body parts?

3.  What are copepods and why can they be a problem to sea slugs? How do the sea slugs appear to deal with too many copepods?

4.  Why does Bernard Picton think head detachment may be an evolutionary adaptation that would help the slugs?

5.  How do the rippling, green-tinged sea slugs get rid of their bodies (should they find a need for this)?

6.  What role might “theft” play in helping sea slugs regrow their bodies? What needs to be stolen and why would the slugs want to steal it?

After Reading:

1.  Growing a new body might sound like a great trick. But what are at least two reasons why sea slugs might want to avoid ditching their bodies unless absolutely necessary?

2.  People can’t regrow body parts (except skin and part of a removed liver). But if you could have one body part that would regrow, what would you wish it to be — and why?