Nassarius, common name nassa mud snails (USA) or dog whelks (UK), is a genus of minute to medium-sized sea snails, marine gastropod molluscs in the family Nassariidae. They are scavengers.

Etymology

The name is derived from the Latin word "nassa", meaning a wickerbasket with a narrow neck, for catching fish. Nassarius would then mean "someone who uses such a wickerbasket for catching fish".

Ecology

Distribution and habitat

Species within this genus are found worldwide. These snails usually live on mud flats or sand flats, intertidally or subtidally.

Life habits

Most Nassarius species are very active scavengers, feeding on crabs and carrion as dead fish, etc. They often burrow into marine substrates and then wait with only their siphon protruding, until they smell nearby food.

Shell description

The shells of species in this genus have a relatively high cyrtoconoid (approaching a conical shape but with convex sides) spire and a siphonal notch. (Described as Aciculina) The shell is turreted, polished, smooth or longitudinally plicate. The inner lip shows the callus sharp, straight, defined. The outer lip is produced in the middle, variced externally. (Described as Nassa) The eyes are situated on the middle of the tentacles. The lingual teeth are arched and pectinated. The uncini show a basal tooth. The foot is large, expanded and bifurcate at its posterior extremity. The operculum is ovate, the margin serrated or entire. The shell is ovate and ventricose. The body whorl is variously sculptured. The aperture is ovate, with a short reflected truncated anterior canal. The inner lip is smooth, often widely spread over with enamel, with a posterior callosity or blunt dentiform plait. The outer lip is dentated, internally crenulated.

Anatomy

The animal has a long siphon.

Human use

Archeology

Several beads made from Nassarius gibbosulus shells are thought to be the earliest known forms of personal adornment, or even jewelry. Two shell beads found in Skhul Cave on the slopes of Mount Carmel, Israel, are thought to be 100,000 years old, whilst another found at Oued Djebbana, Algeria, is believed to be 90,000 years old. A further group of pierced shells, some with red ochre, has been recovered from the Aterian levels at the Taforalt site in Morocco; these Nassarius gibbosulus beads have been securely dated to about 82,000 years ago. All these examples predate several 75,000-year-old Nassarius kraussianus beads which were found at Blombos Cave, South Africa (including some colored with red ochre). These beads had previously been thought to be the oldest examples of jewelry. From A.D. 1130 to 1275, shell beads were manufactured by the inhabitants of the Exhausted Cave near the Clear Creek Ruins. A Southern Sinagua site in Verde Valley, Arizona where "shell played a major role in the economic system of this culture."

Modern uses

Nassarius vibex is a species which is often selected for marine aquaria. It is often confused with Nassarius obsoletus, a cooler water snail less suited to tropical marine aquarium temperatures. In aquaria, the Nassarius is considered nearly indispensable for keeping sand beds clean and healthy, as these snails tend to burrow and plow through the upper layer in a conch-like fashion, keeping algae and detritus from building up visibly on the surface. The shells of various species of Nassarius are popular with shell collectors, and are sometimes used in jewelry and other forms of decoration.

Taxonomy

The genus Nassarius has traditionally been subdivided into several subgenera, based on differences in shell morphology, especially the sculpture: Aciculina, Alectrion, Allanassa, Nassodonta, Niotha, Plicarcularia, Profundinassa, Pygmaeonassa, Telasco, and Zeuxis. However, this division is difficult to define, resulting in much confusion. Even phylogenetic analysis shows that the division into these subgenera appears to be uncertain and unreliable. There seem to be two groups within the genus Nassarius with the closest relationship between the subgenera Zeuxis and Telasco. Even the species within the subgenus Plicarcularia do not belong to a single clade. In the end, the molecular phylogeny did not match the previous morphological phylogeny.

Gallery

Species

In the course of time, more than 1,000 names have been allocated to species in the genus Nassarius, most of which have become synonyms. The following species are accepted names according to the World Register of Marine Species (WoRMS):

Synonyms

Synonymized subgenera