''Calliostoma ligatum'',

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contrast ...

the blue top snail, is a small

prosobranch Prosobranchia was a large taxonomic subclass of sea snails, land snails and freshwater snails. This taxon of gastropods dates back to the 1920s. It has however been proven to be polyphyletic (consisting of more than one lineage of descent). Gene ...

trochid

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

Calliostomatidae Calliostomatidae is a family of sea snails within the superfamily Trochoidea and the clade Vetigastropoda.Gofas, S. (2013). Calliostomatidae. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetail ...

, the

Calliostoma ''Calliostoma'' is a genus of small to medium-sized sea snails with gills and an operculum, marine gastropod molluscs within the family Calliostomatidae, the Calliostoma top snails. Previously this genus was placed within the family Trochidae ...

top snails.

Description

The conical, solid shell has well-rounded globose whorls with six to eight smooth spiral cords per whorl and no umbilicus. Its base is flattened. The surface is encircled by numerous spiral smooth riblets, their interstices closely finely obliquely striate. There are usually seven to nine riblets on the penultimate

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 ...

, about nine on the base. The

spire A spire is a tall, slender, pointed structure on top of a roof of a building or tower, especially at the summit of church steeples. A spire may have a square, circular, or polygonal plan, with a roughly conical or pyramidal shape. Spires are ...

is conic. The

apex The apex is the highest point of something. The word may also refer to: Arts and media Fictional entities * Apex (comics), a teenaged super villainess in the Marvel Universe * Ape-X, a super-intelligent ape in the Squadron Supreme universe *Apex ...

is acute. The sutures are impressed. There are about seven, convex whorls. 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 ...

is rounded (or a trifle angled) around the lower part, slightly convex beneath. The oblique aperture is rounded. The outer lip is fluted within, with a beveled opaque white submargin. The throat is pearly and iridescent;. The simple

columella Lucius Junius Moderatus Columella (; Arabic: , 4 – ) was a prominent writer on agriculture in the Roman Empire. His ' in twelve volumes has been completely preserved and forms an important source on Roman agriculture, together with the wo ...

is arcuate. The base color is chocolate brown to mauve with light tan raised cords, and 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 pearly white. The

is darked and usually purple. The shell is relatively heavy for its size, and its length and width are roughly equal. Length and width up to 24 mm.American Seashells (Second Edition, 1974), R. Tucker Abbott, p. 48, Tryon (1889), Manual of Conchology XI, Academy of Natural Sciences, Philadelphia
(described as ''Calliostoma costatum'')

Distribution

Found from

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S., ...

San Diego San Diego ( , ; ) is a city on the Pacific Ocean coast of Southern California located immediately adjacent to the Mexico–United States border. With a 2020 population of 1,386,932, it is the List of United States cities by population, eigh ...

, California.

Reproduction and development

''Calliostoma ligatum'' is a

broadcast spawner Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of releasing the eggs and sperm, and the act of both sexes is called spawning. Most aquatic animals, except for aquat ...

. Snails spawned in the laboratory in the

San Juan Islands The San Juan Islands are an archipelago in the Pacific Northwest of the United States between the U.S. state of Washington and Vancouver Island, British Columbia, Canada. The San Juan Islands are part of Washington state, and form the core of ...

, WA, USA, during the months of February, March, and April, but only in water that was at least 10 °C. Females release eggs in delicate strands of mucus that break down soon after release. These strands are 1-3mm wide and contain 1-4 eggs across the strand. Ten to ninety eggs are released per pulse, with multiple pulses of eggs released during each spawning event. Males release sperm as a milky white cloud. Fertilization occurs in the water. Eggs are just over 200 um in diameter, and an egg with its protective gelatinous chorion is about 750 um in diameter. Early development proceeds as the

zygote A zygote (, ) is a eukaryotic cell formed by a fertilization event between two gametes. The zygote's genome is a combination of the DNA in each gamete, and contains all of the genetic information of a new individual organism. In multicellula ...

undergoes cleavage in the spiral pattern typical of molluscs and other

protostomes Protostomia () is the clade of animals once thought to be characterized by the formation of the organism's mouth before its anus during embryonic development. This nature has since been discovered to be extremely variable among Protostomia's me ...

. Embryos in culture at 7-9 °C reach the

trochophore A trochophore (; also spelled trocophore) 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, to captur ...

larval stage in 3 days, undergo

torsion Torsion may refer to: Science * Torsion (mechanics), the twisting of an object due to an applied torque * Torsion of spacetime, the field used in Einstein–Cartan theory and ** Alternatives to general relativity * Torsion angle, in chemistry Bi ...

in 4.5–5 days, and hatch 6 days after fertilization.

Veliger A veliger is the planktonic larva of many kinds of sea snails and freshwater snails, as well as most bivalve molluscs (clams) and tusk shells. Description The veliger is the characteristic larva of the gastropod, bivalve and scaphopod ...

larvae stop swimming and begin crawling 9.5 days after fertilization and undergo

metamorphosis Metamorphosis is a biological process by which an animal physically develops including birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Some inse ...

into juvenile snails about 12 days after fertilization.

Ecology and behavior

This snail is found frequently on rocks in the low intertidal zone and in the shallow subtidal zone on large

kelp Kelps are large brown algae seaweeds that make up the order Laminariales. There are about 30 different genera. Despite its appearance, kelp is not a plant - it is a heterokont, a completely unrelated group of organisms. Kelp grows in "underwat ...

, especially the giant kelp ''

Macrocystis ''Macrocystis'' is a monospecific genus of kelp (large brown algae). This genus contains the largest of all the phaeophyceae or brown algae. ''Macrocystis'' has pneumatocysts at the base of its blades. Sporophytes are perennial and the indiv ...

''. ''Calliostoma'' eats a variety of items including the kelp it lives on as well as small sessile organisms and other material that live on rocks or kelp surfaces, including

bryozoa Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquatic invertebrate animals, nearly all living in sedentary colonies. Typically about long, they have a special feeding structure called a l ...

ns, hydroids,

diatom A diatom (Neo-Latin ''diatoma''), "a cutting through, a severance", from el, διάτομος, diátomos, "cut in half, divided equally" from el, διατέμνω, diatémno, "to cut in twain". is any member of a large group comprising sev ...

s, and

detritus In biology, detritus () is dead particulate organic material, as distinguished from dissolved organic material. Detritus typically includes the bodies or fragments of bodies of dead organisms, and fecal material. Detritus typically hosts commun ...

. This snail shows a remarkable range of behavioral reactions to other animals. Snails displayed a flight response with movement rates up to 10 cm/min, often accompanied by shell twisting, between 70% and 100% of the time after contact with the following predatory seastars: ''

Leptasterias hexactis ''Leptasterias hexactis'' is a species of starfish in the family Asteriidae, commonly known as the six-rayed star. It is found in the intertidal zone of the western seaboard of the United States. It is a predator and is unusual among starfish in ...

'', ''

Pycnopodia helianthoides ''Pycnopodia helianthoides'', commonly known as the sunflower sea star, is a large sea star found in the northeast Pacific. The only species of its genus, it is among the largest sea stars in the world, with a maximum arm span of . Adult sunflow ...

'', ''

Pisaster ochraceus ''Pisaster ochraceus'', generally known as the purple sea star, ochre sea star, or ochre starfish, is a common seastar found among the waters of the Pacific Ocean. Identified as a keystone species, ''P. ochraceus'' is considered an important indi ...

'', and '' Evasterias troscheli''. Snails either withdrew into their shells, turned away, or fled after contact with the subtidal crab '' Cancer oregonensis''. ''C. ligatum'' showed only a weak response to contact with predatory snails, but '' Fusitriton oregonensis'' elicited the strongest response of any snail tested. Contact with ''F. oregonensis'' caused about half of the test subjects to exhibit a flight response while others either bit the predator with their

radula The radula (, ; plural radulae or radulas) is an anatomical structure used by molluscs for feeding, sometimes compared to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food ...

, simply turned away, or showed no response. ''C. ligatum'' frequently uses its radula to rasp on, i.e., bite, its non-predators. ''C.ligatum'' bit the non-predatory seastar ''

Henricia leviuscula ''Henricia leviuscula'', commonly called the Pacific blood star, it is a species of sea star found along the Pacific coast of North America. Description They can usually be identified by their bright orange-red color, but there can also be man ...

'' every time they came into contact with each other. After making initial contact the snail reared up, extended its head forward and visibly rasped the upper body wall of ''H. leviuscula'' with its radula. This caused the sea star to move off. ''C. ligatum'' similarly uses its radula to bite, i.e., rasp, on the seastars ''

Solaster stimpsoni ''Solaster stimpsoni'', common names Stimpson's sun star, sun star, orange sun star, striped sunstar, and sun sea star, is a species of starfish in the family Solasteridae. Description ''Solaster stimpsoni'' is a large species, growing up to 5 ...

'' about 60% of the time, and ''

Dermasterias imbricata The leather star (''Dermasterias imbricata'') is a sea star in the family Asteropseidae found at depths to off the western seaboard of North America. It was first described to science by Adolph Eduard Grube in 1857. Description The leather st ...

'' about 40% of the time. ''C. ligatum'' also routinely bit (rasped) the snails '' Ceratostoma foliatum'', '' Searlesia dira'' and '' Amphissa columbiana'' which caused these snails to move away from ''C. ligatum''.

References

External links

* https://scholarsbank.uoregon.edu/xmlui/bitstream/handle/1794/6867/Lane.PDF?sequence=1
''Calliostoma ligatum'' (Gould, 1849)
Wallawalla University * {{Taxonbar, from=Q2212346 ligatum Gastropods described in 1849