snail age

[berniechip]

Hi Dr. Ron,

We were having a discussion and wondering if there is a way to tell a snails age. Someone heard you could count the rings of growth, somewhat like you would on a tree. Is this true? A friend found a giant queen conch shell at the beach, we wanted to know how old it was.

Thanks in advance
Bernie

[rshimek]

Hi Bernie,

A few snails, mostly ones found in colder waters, such as the so-called "margarite snail" (= Tegula funebralis from the Pacific NW) lay down annual growth rings, sort of like "notches" on the body whorl. I have counted as many as 140 of these rings. Presumably the animal was at least that many years old.

Most snails, however, don't do this, they grow continuously throughout their lives. Size is often related more to food availability than it is to age. One can find what appear to be very old snails (the shell is highly eroded, etc) that are quite small (for the particular species) in what appears to be marginal habitats. They seem be old and small, stunted probably, due to the lack of food. The converse is also true.

After the animals reach sexual maturity, the growth rate slows as excess energy is put into reproduction rather than growth. Generally, however, the animal continues to grow. Under good conditions, a queen conch can proabably reach normal adult size in 3 to 4 years. Really large ones could be in excess of 20 years old.