
''Megastraea undosa'', common name the wavy turban snail, 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
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 ...
Turbinidae, the turban snails.
This species is native to the coast of
California
California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...
.
Distribution
This species occurs in the eastern
Pacific Ocean
The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...
from
California
California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...
, USA to Central
Baja California
Baja California, officially the Free and Sovereign State of Baja California, is a state in Mexico. It is the northwesternmost of the 32 federal entities of Mexico. Before becoming a state in 1952, the area was known as the North Territory of B ...
, Mexico.
Description
One of the largest gastropod shells found on the Southern California coast, this species varies between 40 mm and 145 mm. The shell lacks an
umbilicus, and has a turbinate-conical shape. Like other shells of the family
turbinidae it is composed of a thick inner nacreous layer, covered by a thinner porcellanous layer. In this species both are covered by a dark brown shaggy
periostracum
The periostracum ( ) is a thin, organic coating (or "skin") that is the outermost layer of the shell of many shelled animals, including molluscs and brachiopods. Among molluscs, it is primarily seen in snails and clams, i.e. in gastropods an ...
in life. The periphery of the shell forms a twisted ridge at the outer edge of each
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).
In nature
File:Photograph and axial plane floral diagra ...
. Each whorl also has regular, coarsely sculpted rows of fine knobs and folds. The base is marked with several spiral cords concentric to the arcuated
columella
Lucius Junius Moderatus Columella (, Arabic: ) was a prominent Roman writer on agriculture in the Roman Empire.
His in twelve volumes has been completely preserved and forms an important source on Roman agriculture and ancient Roman cuisin ...
which has a pearly groove. The unusual
operculum has four strong ridges on its outer side decorated with hard shelly bristles that radiate in a curvilinear fashion from its pointed edge.
Rogers, Julia Ellen (1907), The shell book
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Habitat
This large snail inhabits rocky shores in shallow waters, generally protected areas below the low tide level.
References
W.H. Dall (1910) ''New Species of West American Shells''; The Nautilus v. 23, 1910
External links
*
* Alf A. & Kreipl K. (2011) ''The family Turbinidae. Subfamilies Turbininae Rafinesque, 1815 and Prisogasterinae Hickman & McLean, 1990.'' In: G.T. Poppe & K. Groh (eds), ''A Conchological Iconography.'' Hackenheim: Conchbooks. pp. 1–82, pls 104–245.
* Williams, S.T. (2007). Origins and diversification of Indo-West Pacific marine fauna: evolutionary history and biogeography of turban shells (Gastropoda, Turbinidae). Biological Journal of the Linnean Society, 2007, 92, 573–592.
Proo, Sag del, Larval and early juvenile development of the wavy turban snail, Megastraea undosa (Wood, 1828) (Gastropoda : Turbinidae); The Veliger 46 (4), 2003
{{DEFAULTSORT:Megastraea Undosa
undosa
Gastropods described in 1828
Taxa named by William Wood (zoologist)