''Vermicularia knorrii'', commonly known as the Florida worm snail, is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

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 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 ...

Turritellidae Turritellidae, common name the "tower shells" or "tower snails", is a taxonomic family of small to medium-sized sea snails, marine gastropod molluscs in the clade Sorbeoconcha. These snails are filter feeders. This method of feeding is s ...

. ''V. knorrii'' has been concluded to be the junior synonym to ''Vermicularia lumbricalis''. The shell of Florida worm snail is light brown or tan in color with an apex that is white. It is found living in reefs on the coasts of the southern states of the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

to the top of

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

. ''V. knorri'' use their ciliated appendages to trap plankton and sperm.

Distribution

This species is found in the

from

Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and to ...

North Carolina North Carolina () is a state in the Southeastern region of the United States. The state is the 28th largest and 9th-most populous of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, Georgia and So ...

, the Gulf Coast, the eastern coast of

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, Barbuda,

Cuba Cuba ( , ), officially the Republic of Cuba ( es, República de Cuba, links=no ), is an island country comprising the island of Cuba, as well as Isla de la Juventud and several minor archipelagos. Cuba is located where the northern Caribbea ...

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, and

Bermuda ) , anthem = "God Save the King" , song_type = National song , song = " Hail to Bermuda" , image_map = , map_caption = , image_map2 = , mapsize2 = , map_caption2 = , subdivision_type = Sovereign state , subdivision_name = , e ...

''. Vermicularia knorrii'' is strictly marine and does not live in brackish or fresh waters and is not terrestrial. ''V. knorrii'' is found in waters with temperatures around .

Habitat

''Vermicularia knorrii'' habitat ranges from 35.34°N to 12°N and 92°W to 64.7°W. They can be found between depths of , but typically live in water . The deepest recorded depth of ''Vermicularia knorrii'' is about on the continental slope of Texas, but it may have been another species wrongfully identified at the greater depths. This places the Florida worm snail's habitat in the epipelagic and mesopelagic zones most often being found in the

photic zone The photic zone, euphotic zone, epipelagic zone, or sunlight zone is the uppermost layer of a body of water that receives sunlight, allowing phytoplankton to perform photosynthesis. It undergoes a series of physical, chemical, and biological proc ...

. Unlike other ''Vermicularia'' species, the Florida worm snail does not form inter-coil structures but rather lives in hard substrates such as

coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and sec ...

s and

sponge Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through t ...

s. It stays in the substrate by cementing itself in it. ''V. knorrii'' can be found in "boiler" reefs, rim reefs, subtidal, and patch reefs. It appears to be vulnerable of desiccation, or the removal of water, usually during low tides.

Shell

The shell of this species is in length. When the shell is intact, the apex is pure white, somewhat translucent, and tightly coiled similarly to that of the genus '' Turritella''. The regularly coiled apex is around in length. The subsequent whorls are brown, and they are loosely and irregularly coiled, such that the whorls do not touch. Their irregular shape helps them anchor into sponges, rocks, and corals. The irregular shape of their shells gives the Florida worm snail its name as they resemble the tubes made by tube worms. As they grow, '' Vermicularia'' shells start to uncoil due to the need to access food and to attach to substrate they live in stabley. The shells are also used by hermit crabs, such as ''

Calcinus verrillii ''Calcinus verrillii'', commonly known as Verrill's hermit crab, is a species of hermit crab in the genus ''Calcinus'' which is endemic to Bermuda. It was first described by the American zoologist Mary J. Rathbun and named in honour of the Ame ...

'', as shelter. The odd shapes of the worm snail shells affect the symmetry of the

uropod Uropods are posterior appendages found on a wide variety of crustaceans. They typically have functions in locomotion. Definition Uropods are often defined as the appendages of the last body segment of a crustacean. An alternative definition sugge ...

Feeding

Due to the Florida worm snail living in sponges and corals, it is sessile and does not actively hunt for food. It is a

suspension feeder Filter feeders are a sub-group of suspension feeding animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feedin ...

and catches food by expelling cilia and mucus from its

mantle A mantle is a piece of clothing, a type of cloak. Several other meanings are derived from that. Mantle may refer to: *Mantle (clothing), a cloak-like garment worn mainly by women as fashionable outerwear **Mantle (vesture), an Eastern Orthodox ve ...

. The mantle cavity elongates the gill surface and pushes out the cilia. The cilia flow with the current, creating a mucus net that catches

plankton Plankton are the diverse collection of organisms found in Hydrosphere, water (or atmosphere, air) that are unable to propel themselves against a Ocean current, current (or wind). The individual organisms constituting plankton are called plankt ...

. The snail then retracts the strings and uses its

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 ...

to eat the food.

Reproduction and life cycle

Although not much is known about the reproductive cycle of ''Vermicularia knorrii'', it is thought to be gonochoristic and broadcast spawn. It is theorized that ''Vermicularia knorrii'' has similar reproductive and life stages to its sister gastropod, ''

Vermicularia spirata ''Vermicularia spirata'', common name the West Indian worm-shell or the West Indian wormsnail, is a species of sea snail, a marine gastropod mollusc in the family Turritellidae. Juveniles can move around, but larger individuals become sessile. ...

''. ''Vermicularia spirata'' is protandrous hermaphroditic with small males being free living and eventually attaching to substrate when switching sexes. Both males and females have open pallial ducts, which serves as the fertilization pouch and seminal receptacle in the female. Females receive sperm from nearby males and fertilization occurs. Eggs are brooded in the mantle cavity of the mantle which hatch as veliger larvae with shells with two and a half whorls. This is likely the reproduction cycle that ''V. knorrii'' follow as ''V. spirata'' have very similar gross morphology.

Gallery

Wsnail1.jpg, ''Vermicularia knorrii'' Wsnail2.jpg, ''Vermicularia knorrii'' Wsnail3.jpg, ''Vermicularia knorrii'' Wsnail4.jpg, ''Vermicularia knorrii'' Wsnail5.jpg, ''Vermicularia knorrii''

References

External links

* https://conchology.be/t=263&family=TURRITELLIDAE%20TURRITELLINAE&fullspecies=Vermicularia%20knorrii&shellID=1813 * https://www.aquamaps.org/receive.php?type_of_map=regular&map=cached {{Taxonbar, from=Q3168010 Turritellidae Gastropods described in 1843