One
of our patrons was reading George R.R. Martin’s A Song of Ice and Fire fantasy series, on which the HBO television series Game of Thrones is based.
Presumably to give things a more fantastical flavor, Martin made up his own
system of telling time, having characters refer to times such as “the hour of
the bat,” “the hour of the wolf,” and “the hour of the eel.” “I understand the
wolf and the bat,” our patron said, “because they’re both associated with
night. But why the eel? Are they nocturnal?”
While
we can’t explain why Martin makes the writing decisions he does, we could find
information about eels. We looked them up first in the World Book Encyclopedia.
It didn’t tell us anything about when they were active, but we did learn that
they undergo several metamorphoses over the course of their lives. American and
European eels travel to the Sargasso Sea to lay their eggs. The eggs hatch into
transparent larvae shaped like willow leaves. The larvae change into small transparent
eels, called glass eels. By the time they reach the coast, the small eels have
developed a greenish-brown color. No longer baby glass eels, they’re now
juvenile eels, called elvers. The elvers travel inland and grow into yellow
eels (though they’re more yellow-green or yellow-brown). During this stage,
which can last many years, they reach their full size, three to five feet for
females and around one-and-a-half to three feet for males. Eventually, they
reach sexual maturity and turn black and silver. Now, they’re called silver
eels. They fatten up for their journey back to the Sargasso Sea to mate. (They
don’t eat on their voyage, and their digestive system actually starts to break
down.) After mating, they die. Because they are born in the ocean, grow up in
fresh water, and then go back to the ocean to spawn, eels are catadromous, and
they’re the only such fish in North America.
As
interesting as this is, it didn’t answer our question. We found that
information on the U.S. Fish and Wildlife Service website. Freshwater eels are
indeed nocturnal, at least during their yellow phase. They come out at night to
eat crabs, fish, insects, eggs, clams, and frogs. They have small teeth and
weak jaws, so to break off pieces of food that’s too big to swallow whole,
they’ll grip it in their mouths and spin their bodies. They can spin up to
fourteen times a second, almost three times as fast as an Olympic ice skater.
Eels can move just as well forward and backward, and they can move over land
through wet grass and mud because they’re able to absorb oxygen through their
skin.