amphibious-capable of living both in and out of water; in some cases, may not survive if forced to live either entirely in or entirely out of water.

apertural barriers-the "teeth" and lamellae seen inside the opening of the shell.

apex-the uppermost point of a snail's shell.

arboreal-living in trees.

biological control-control of pest organisms using other organisms (usually introduced) as predators, parasites, or pathogens of the pest.

biomass-the total amount of biological material in an area or ecosystem.

carnivorous-organism that feeds on other animals.

columella-the central column of a snail's shell, formed as successive whorls coil around a central axis.

decollation-loss of the upper whorls of the shell.


endemic-indigenous organisms occurring only in the designated geographical area, such as an island or country; in the context of this book, occurring only in the Samoan Islands.

estuarine-habitat lying at the interface between freshwater and marine environments; usually the mouths of streams and rivers.

fauna-the full complement of animals living in an area.

genus-the scientific term for a group of closely related species.

genera-plural of genus.

growth lines-fine transverse ridges (see sculpture) formed by the incremental addition of shell material at the growing edge of the shell.

indigenous-organisms occurring naturally in a designated geographical area, but also elsewhere (see also endemic); in the context of this book, occurring naturally in the Samoan Islands, but also elsewhere.

Indo-Pacific-the geographic area encompassing the Indian and Pacific Oceans, the islands within them, and the surrounding continental edges.

intertidal-the strip of land lying between the high and low tide marks.

IUCN-the International Union for the Conservation of Nature and Natural Resources, known also as the World Conservation Union.

keeled-shell with a sharply angled periphery.

lamella-plural "lamellae"; flanges or teeth forming barriers inside the aperture of a snail's shell.

Melanesia- one of the three major subdivisions of the islands of the Pacific, roughly comprising the islands of the southwestern Pacific, south of the equator, from New Guinea to Fiji, and including the Solomon Islands, Vanuatu and New Caledonia.

Micronesia- one of the three major subdivisions of the islands of the Pacific, roughly comprising the islands of the western Pacific, north of the equator, from Palau in the west and the Mariana Islands in the north, to the Gilbert Islands (part of Kiribati) in the east, and including the Federated States of Micronesia and the Marshall Islands.

morphological-relating to the physical form of an organism.

native-organisms occurring naturally in a particular area; also termed indigenous.

non-indigenous-organisms not occurring naturally in a particular area; also termed introduced, alien, exotic, adventive; in the context of this book, not occurring naturally in the Samoan Islands.

operculate-possession of an operculum; a snail that possesses an operculum.

operculum-the trap-door like structure, attached to the body of the snail, that seals the shell opening (aperture) when the snail withdraws into its shell; only possessed by certain groups of snails.

periostracum-the thin outer protein layer of a snail's shell.

periphery-the outermost edge of the shell whorl; the midline of the whorl.

Polynesia-one of the three major subdivisions of the islands of the Pacific, a roughly triangular region stretching from New Zealand in the south, to Hawaii in the north and the Juan Fernandez Islands in the east.

predation-the act of one organism (the predator) eating another (the prey).

protoconch-the shell formed within the egg; becomes the apex of the growing shell.

pulmonate-snail that breathes with a lung; lacks an operculum.

salinity-the amount of salt in the water.

sculpture-patterns of ridges and grooves running spirally or transversely along or across the shell.

species-the scientific term referring to a kind of organism, often defined as those individuals among which successful breeding could potentially take place; individuals that could not interbreed successfully would be considered as belonging to a different species.

striate-shell with sculpture of transverse lines.

suture-the junction between successive whorls of a snail's shell.

synonym-in the context of this book, two or more scientific names of an organism are synonyms if they refer to the same real species; the name published first is the senior synonym and is the one that must be used; later names are junior synonyms.

taxonomy-the scientific description, naming, and classification of organisms.

umbilicus-the cavity that opens at the base of a snail's shell; may vary considerably in size, and may be absent in some species.

whorl-each successive coil of a snail's shell.