Snail mail

Snail mail and smail (from snail + mail)—named after the snail with its slow speed—refers to letters and missives carried by conventional postal delivery services. The phrase refers to the lag-time between dispatch of a letter and its receipt, versus the virtually instantaneous dispatch and delivery of its electronic equivalent, e-mail.

It is also known, more neutrally, as paper mail, postal mail, land mail, or simply mail and post. An earlier term of the same type is surface mail, coined retrospectively after the development of airmail. This happened between the 1970s to 1990s.

Snail mail penfriends or penpals are those that communicate with one another through the postal system, rather than on the internet which has become the more common medium.

Some online groups also use paper mail through regular gift or craft hot topics. In some countries, services are available to print and deliver emails to those unable to receive email, like people with no computers or internet access.

Snail

Snail is a common name that is applied most often to land snails, terrestrial pulmonate gastropod molluscs.

However, the common name "snail" is also applied to most of the members of the molluscan class Gastropoda that have a coiled shell that is large enough for the animal to retract completely into. When the word "snail" is used in this most general sense, it includes not just land snails but also thousands of species of sea snails and freshwater snails. Occasionally a few other molluscs that are not actually gastropods, such as the Monoplacophora, which superficially resemble small limpets, may also informally be referred to as "snails".

Snail-like animals that naturally lack a shell, or have only an internal shell, are mostly called slugs, and land snails that have only a very small shell (that they cannot retract into) are often called semi-slugs.

Overview

Snails that respire using a lung belong to the group Pulmonata, while those with gills form a polyphyletic group; in other words, snails with gills form a number of taxonomic groups that are not necessarily more closely related to each other than they are related to some other groups. Both snails that have lungs and snails that have gills have diversified so widely over geological time that a few species with gills can be found on land and numerous species with lungs can be found in freshwater. Even a few marine species have lungs.