Xenophoridae
Encyclopedia
Xenophoridae, common name
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...

 carrier shells, are a taxonomic family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 of medium-sized to large sea snails, marine
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...

 gastropod mollusks in the clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...

 Littorinimorpha
Littorinimorpha
Littorinimorpha is a large clade of gastropods within Hypsogastropoda consisting primarily of marine species, but also aquatic and terrestrial species as well....

.

According to taxonomy of the Gastropoda by Bouchet & Rocroi (2005)
Taxonomy of the Gastropoda (Bouchet & Rocroi, 2005)
The taxonomy of the Gastropoda as it was revised by Philippe Bouchet and Jean-Pierre Rocroi is currently the most up-to-date overall system for classifying gastropod mollusks...

 the family Xenophoridae has no subfamilies.

Distribution

The Xenophoridae live on sand and mud bottoms of the continental shelves
Continental shelf
The continental shelf is the extended perimeter of each continent and associated coastal plain. Much of the shelf was exposed during glacial periods, but is now submerged under relatively shallow seas and gulfs, and was similarly submerged during other interglacial periods. The continental margin,...

 and the continental slopes
Continental margin
The continental margin is the zone of the ocean floor that separates the thin oceanic crust from thick continental crust. Continental margins constitute about 28% of the oceanic area....

 of the subtropical and tropical seas and range from very shallow water to depths of more than 1,400 meters.

Shell description

Xenophorids are unusual in that in many of the species the animal cements small stones or shells to the edge of the shell
Gastropod shell
The gastropod shell is a shell which is part of the body of a gastropod or snail, one kind of mollusc. The gastropod shell is an external skeleton or exoskeleton, which serves not only for muscle attachment, but also for protection from predators and from mechanical damage...

 as it grows, thus the shells of those species are sometimes humorously referred to as "shell-collecting shells". The genus name Xenophora
Xenophora
Xenophora, common name carrier shells, is a genus of medium sized to large sea snails, marine gastropod mollusks in the family Xenophoridae, the carrier snails or carrier shells.-Description:...

comes from two ancient Greek words and means "bearing (or carrying) foreigners".
The shells are small to rather large (diameter of base without attachments 19-160 mm; height of shell 21-100 mm), depressed to conical, with narrow to wide, simple to spinose peripheral edge or flange separating spire
Spire (mollusc)
A spire is a descriptive term for part of the coiled shell of mollusks. The word is a convenient aid in describing shells, but it does not refer to a very precise part of shell anatomy: the spire consists of all of the whorls except for the body whorl...

 from base. Aperture
Aperture (mollusc)
The aperture is an opening in certain kinds of mollusc shells: it is the main opening of the shell, where part of the body of the animal emerges for locomotion, feeding, etc....

 large, base broad, rather flattened, often umbilicate. Periostracum
Periostracum
The periostracum is a thin organic coating or "skin" which is the outermost layer of the shell of many shelled animals, including mollusks and brachiopods. Among mollusks it is primarily seen in snails and clams, i.e. in bivalves and gastropods, but it is also found in cephalopods such as the...

 very thin or wanting. Protoconch
Protoconch
A protoconch is an embryonic or larval shell of some classes of molluscs, e.g., the initial chamber of an ammonite or the larval shell of a gastropod...

 depressed-conical, multispiral (in one species paucispiral). Teleoconch
Gastropod shell
The gastropod shell is a shell which is part of the body of a gastropod or snail, one kind of mollusc. The gastropod shell is an external skeleton or exoskeleton, which serves not only for muscle attachment, but also for protection from predators and from mechanical damage...

 usually with foreign objects attached in spiral series to peripheral flange and, sometimes, remainder of dorsum, at least on early whorls
Whorl (mollusc)
A whorl is a single, complete 360° revolution or turn in the spiral growth of a mollusc shell. A spiral configuration of the shell is found in of numerous gastropods, but it is also found in shelled cephalopods including Nautilus, Spirula and the large extinct subclass of cephalopods known as the...

. Operculum
Operculum (gastropod)
The operculum, meaning little lid, is a corneous or calcareous anatomical structure which exists in many groups of sea snails and freshwater snails, and also in a few groups of land snails...

 horny, yellowish to brown, nucleus lateral, with simple growth lamellae, sometimes with conspicuous radial striae or hollow radial ribs.

Genera

Genera within the family Xenophoridae include:
  • Onustus Swainson, 1840 - synonyms: Trochotugurium Sacco, 1896; Tugurium Fischer in Kiener, 1879
  • Stellaria
    Stellaria (gastropod)
    Stellaria is a genus of large sea snails, marine gastropod mollusks in the family Xenophoridae, the carrier shells.-Description:Shells medium-sized to large , rather depressed to moderately high-spired, widely umbilicate, with wide peripheral flange which is simple in...

    Möller, 1832 - synonym: Haliphoebus Fischer in Kiener, 1879; Xenophora (Stellaria) Schmidt, 1832
  • Xenophora
    Xenophora
    Xenophora, common name carrier shells, is a genus of medium sized to large sea snails, marine gastropod mollusks in the family Xenophoridae, the carrier snails or carrier shells.-Description:...

    Fischer von Waldheim, 1807 - type genus

External links

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