How old is a lobster?

age-of-a-lobster

Lobster
Photo by Roberto Rodriguez, Public Domain

Adapted from The Vancouver Sun by Nancy Carson
Level 1

Now scientists know
the age of a lobster.
They count the lobster’s rings.
We do this with trees.
We count the rings in the wood.


How old are they?
Nobody knows how long lobsters live.
Some people think they live to 100.
Before now, scientists guessed their age.
They looked at their size and other things.

New information
Lobsters, crabs and shrimp
grow one ring a year.
And they grow them
in places inside the animal.
So, the rings cannot be seen.

Crabs and shrimpPhoto by Vera Kratochvil, Public Domain

Crabs and shrimp
Photo by Vera Kratochvil, Public Domain

Other sea life
For years, scientists knew a fish’s age.
They counted the rings in a fish’s ear.
They counted a shark’s rings
in its backbone.
The rings on a clam shell tell how old it is.

The rings on a clam shell tell its age.Photo by Peter Griffin, Public domain

The rings on a clam shell tell its age.
Photo by Peter Griffin, Public domain

The problem
Animals like lobsters, crabs and shrimps
have shells on their bodies.
These animals are called crustaceans.
The animal grows. Its shell gets too small.
So, the shell cracks. It falls off.
This is called moulting.
Scientists thought that
these shells had the rings.
The rings fell off, they thought.
So, they could not count them.
This is why they did not know their ages.

A surprise
Scientists looked at lobsters closely.
They found growth rings are on the eye stalk.
An eye stalk is like the stem of a flower.
The stem holds up the flower.
A lobster’s eye stalk has
an eyeball on the end of it!
Scientists also found growth rings
in the stomachs of lobsters.
So, the shell of a lobster or shrimp comes off.
But the rings stay.
Soon we will know. Do lobsters live to 100?