| Crisilla picta | |
|---|---|
 | |
| Crisilla picta | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Gastropoda |
| Clade: | Caenogastropoda |
| Clade: | Hypsogastropoda |
| Order: | Littorinimorpha |
| Family: | Rissoidae |
| Genus: | Crisilla |
| Species: | C. picta |
| Binomial name | |
| Crisilla picta | |
| Synonyms [2] | |
| |
Crisilla picta is a species of minute sea snail with an operculum; this organism is a marine gastropod mollusk or micromollusk in the family Rissoidae. [4]
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined.
Sea snail is a common name for slow moving marine gastropod molluscs usually with visible external shells, such as whelk or abalone. They share the taxonomic class Gastropoda with slugs, which are distinguished from snails primarily by the absence of a visible shell.
The operculum, meaning little lid, is a corneous or calcareous anatomical structure like a trapdoor which exists in many groups of sea snails and freshwater snails, and also in a few groups of land snails; the structure is found in some marine and freshwater gastropods, and in a minority of terrestrial gastropods, including the families Helicinidae, Cyclophoridae, Aciculidae, Maizaniidae, Pomatiidae, etc.
