''Onustus longleyi'' is a

species 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. It is the basic unit of Taxonomy (biology), ...

of large

sea snail Sea snails are slow-moving marine (ocean), marine gastropod Mollusca, molluscs, usually with visible external shells, such as whelk or abalone. They share the Taxonomic classification, taxonomic class Gastropoda with slugs, which are distinguishe ...

, a marine

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Xenophoridae Xenophoridae, common name, commonly called carrier shells, is a family (biology), family of medium-sized to large sea snails, marine (ocean), marine gastropod mollusks in the clade Littorinimorpha. Distribution The Xenophorids live on sand and ...

, the carrier shells.

Description

These sea snails are usually a white-cream color, with a cream underside. Their spire is rather smooth, and the lower edge of the shell is quite irregular and jagged. The

umbilicus Umbilicus may refer to: *The navel or belly button *Umbilicus (mollusc), a feature of gastropod, Nautilus and Ammonite shell anatomy *Umbilicus (plant), ''Umbilicus'' (plant), a genus of over ninety species of perennial flowering plants *Umbilicus ...

is straight and open to the apex. Small bits of their shells are cemented at the suture. Most of these gastropods have a calcareous external shell. Others lack a shell completely, or have reduced internal shells. These snails are known for their tendency to pick up other shells, skeletal fragments, rocks, or corals (sometimes still alive) from their surrounding environment and cement these objects to their own shells. The result looks like a pile of shells on the seafloor. Often, sponges and serpulid worm tubes are found encrusting the xenophorid shell - as they contribute to the illusion that a xenophorid is simply a patch of the seafloor. Xenophora carrier snails do this as a camouflage defense against predators. A "glue" or mucus is secreted from the outer portion of their body, called the mantle or pallium in Latin, which means cloak or robe. This mucus is a combination of protein,

calcium carbonate Calcium carbonate is a chemical compound with the chemical formula . It is a common substance found in Rock (geology), rocks as the minerals calcite and aragonite, most notably in chalk and limestone, eggshells, gastropod shells, shellfish skel ...

, etc. that bind together and harden to form the outer shell. It is constantly secreted to enlarge the spiral shell, in a 360-degree manner, as the soft-bodied snail grows. The marine snail "collects" or attaches the bits to the outside edges of the spiral or whorled edges. Their "foot" is the part of their body that they move with.

Life History Traits

This species reproduces sexually. Their

embryo An embryo ( ) is the initial stage of development for a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sp ...

s develop into planktonic

trochophore A trochophore () is a type of free-swimming planktonic marine larva with several bands of cilia. By moving their cilia rapidly, they make a water eddy to control their movement, and to bring their food closer in order to capture it more easily. ...

larvae, and later into juvenile veligers before becoming fully grown adults. These

carnivore A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they ar ...

s consume low growing organisms, such as low-growing grasses and algae. The animals move by extending their powerful foot, anchoring the end in the substrate with the operculum (gill cover), and jerking the shell forward in a leaping movement.

Distribution

''Onustus longleyi'' is distributed along the American Atlantic coast from

North Carolina North Carolina ( ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, South Carolina to the south, Georgia (U.S. stat ...

to the

Gulf of Mexico The Gulf of Mexico () is an oceanic basin and a marginal sea of the Atlantic Ocean, mostly surrounded by the North American continent. It is bounded on the northeast, north, and northwest by the Gulf Coast of the United States; on the southw ...

and the

Caribbean The Caribbean ( , ; ; ; ) is a region in the middle of the Americas centered around the Caribbean Sea in the Atlantic Ocean, North Atlantic Ocean, mostly overlapping with the West Indies. Bordered by North America to the north, Central America ...

reaching

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

in the South. It can be found between 180 and 695 meters.Kreipl, K. & Alf, A. (1999): ''Recent Xenophoridae''. 148 pp. incl. 28 color plts. ConchBooks, Hackenheim, . They are usually found on

continental shelves A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an island ...

and

continental slope A continental margin is the outer edge of continental crust abutting oceanic crust under coastal waters. It is one of the three major zones of the ocean floor, the other two being deep-ocean basins and mid-ocean ridges. The continental margi ...

s in subtropical and tropical regions. They mostly occupy marine environments, but can also be found in freshwater and terrestrial environments.

References

3. ''Onustus longleyi'' (Bartsch, 1931) in GBIF Secretariat (2021). GBIF Backbone Taxonomy. Checklist dataset https://doi.org/10.15468/39omei accessed via GBIF.org on 2022-04-25. 4. Springsteen, F.J. and F.M. Leobrera 1986 Shells of the Philippines. Carfel Seashell Museum. Metro Manila, Philippines. 377 p. 5. MolluscaBase eds. (2022). MolluscaBase. ''Xenophora (Onustus) longleyi'' Bartsch, 1931. Accessed through: World Register of Marine Species at: https://www.marinespecies.org/aphia.php?p=taxdetails&id=743991 on 2022- 04-25 {{Taxonbar, from=Q7095107 Xenophoridae Gastropods described in 1931