''Mangelia sagena'' is a species of

sea snail 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 ...

, a marine

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...

in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Mangeliidae Mangeliidae is a monophyletic family of small to medium-sized, predatory sea snails, marine gastropod mollusks in the superfamily Conoidea. Bouchet, P. (2011). Mangeliidae P. Fischer, 1883. In: MolluscaBase (2016). Accessed through: World Regis ...

Description

The length of the shell attains 5 mm, its diameter 2.2 mm. (Original description) The small shell is vitreous white. It is few whorled, the

body whorl The body whorl is part of the morphology of the shell in those gastropod mollusks that possess a coiled shell. The term is also sometimes used in a similar way to describe the shell of a cephalopod mollusk. In gastropods In gastropods, the b ...

much the largest. It contains a smooth

protoconch A protoconch (meaning first or earliest or original shell) is an embryonic or larval shell which occurs in some classes of molluscs, e.g., the initial chamber of an ammonite or the larval shell of a gastropod. In older texts it is also called ...

of1½

whorl A whorl ( or ) is an individual circle, oval, volution or equivalent in a whorled pattern, which consists of a spiral or multiple concentric objects (including circles, ovals and arcs). Whorls in nature File:Photograph and axial plane floral ...

and somewhat more than 3½ subsequent whorls. The suture is inconspicuous, not constricted. The fasciole is feebly marked. The axial

sculpture Sculpture is the branch of the visual arts that operates in three dimensions. Sculpture is the three-dimensional art work which is physically presented in the dimensions of height, width and depth. It is one of the plastic arts. Durable sc ...

consists of (on the body whorl about a dozen) low rounded ribs with much wider interspaces, crossing the whorls, and well-marked close incremental lines. The spiral sculpture consists of (on the first adult whorl 2, on the next 3, and on the body whorl 8 or 9) sharp fine threads with much wider interspaces, a little swollen where they override the ribs, and forming by the intersection a rather open reticulum. In the interspaces are very fine close spiral striae. This sculpture covers the shell. The

aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane. An opt ...

is narrow, hardly wider than the

siphonal canal The siphonal canal is an anatomical feature of the shells of certain groups of sea snails within the clade Neogastropoda. Some sea marine gastropods have a soft tubular anterior extension of the mantle called a siphon through which water is ...

. The

anal sulcus The anal sulcus, also called the anal sinus or anal canal, in Gastropods is a notch, a shelly tube at the top of the aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and fo ...

is very shallow. The outer lip is hardly thickened. The columella is short and straight, axis impervious. Dall W. H. (1927). Small shells from dredgings off the southeast coast of the United States by the United States Fisheries Steamer "Albatross", in 1885 and 1886; Proceedings of the United States National Museum, 70(18): 1–134

Distribution

This marine species was found off Fernandina, Florida, USA at a depth of 805 m.

References

External links

Smithsonian Institution: ''Daphnella sagena''
* {{DEFAULTSORT:Mangelia Sagena sagena Gastropods described in 1927