Atlanta lesueurii
Encyclopedia
Atlanta lesueurii is a species
of sea snail
, a holoplankton
ic marine
gastropod mollusk in the family
Atlantidae
.
is transparent, thin and fragile, with a smooth surface (lacking raised sculpture
). The spire
is very small, somewhat elevated and compact, consisting of about 2½ whorls. Spire sutures are deep, with the result that the whorls are somewhat rounded in profile and can easily be distinguished. After metamorphosis the outermost whorl enlarges and inflates rapidly and the keel becomes progressively taller, becoming very tall in large adults and having a truncate leading edge. The keel base and spire sutures are colorless.
Main features for the recognition of this species are the protoconch
composed of just 2¼-3 convex whorls
, separated by an incised suture and the absence of any ornament. The first teleoconch whorl expands rapidly and bears a well-developed flange-like keel. In the largest specimens the final three quarters of the teleoconch separates from the penultimate whorl.
Eyes are type b, with a large lens. The Operculum
is the type b. Radula
is type I, with a narrowly triangular shape.
Atlanta lesueurii is the large species in the genus Atlanta, but Atlanta peronii
is larger.
Atlanta lesueurii resembles closely Atlanta oligogyra
, in which, however, the first whorls are separated by a superficial suture and the shell remains much smaller.
Overview of description:
The first fossil specimens of Atlanta lesueurii has been found from Pliocene
in Tiep, Roxas
(map) and Anda, Pangasinan
, Luzon, Philippines in 2001 (published in 2007).
patterns of Atlanta lesueurii (among the 13 species of heteropods in the study) were investigated off leeward Oahu
, Hawaii in waters overlying a bottom depth of 2,000 m (between 9 and 11 km offthe coast) by Seapy (1990). Heteropods were collected during day and night periods using paired, opening-closing BONGO nets at 50-m depth intervals between the surface and 200 m and at 200–300 m and 300–400 m. Three or four replicated tows were taken in each depth interval. Atlanta lesueurii was found to be the most abundant species, with a maximal density of 59 individuals per 1,000 m3 in a daytime 0–45 m depth interval. The species ranged from the surface to 140 m during both day and night periods. There was an apparent partial populational migration from a depth interval of 45–90 m during the day to 0–45 m at night. However, high variability in densities between the replicated tows in each of the depth intervals resulted in statistically non-significant differences between day and night periods for each of the depth intervals.
In a subsequent study off leeward Oahu (Seapy, 2008), duplicate tows were taken with a MOCNESS multiple, opening-closing net system during day and night periods at three stations located 1, 5 and 15 nm off the island in fall and spring sampling periods. Mean densities were computed (as numbers of individuals beneath 100 m2 of ocean surface) during day and night periods at each station. As in the 1990 study, Atlanta lesueurii was the most abundant species in the fall, although it was a close second to Atlanta plana
in the spring. Comparisons were made using the nighttime density data to avoid issues such as daytime net avoidance and to include increased nighttime abundances resulting from possible nocturnal vertical migrator species. Atlanta lesueurii was found to be most abundant at the offshore (15 nm) station during both seasons. Offshore to inshore abundance decreased most dramatically in the fall; from mean nighttime densities of 480 (15 nm) to 124 (5 nm) to 37 (1 nm) individuals beneath 100 m2 of ocean surface. At the 15 nm station the species ranged downward to the greatest depths; to the 120–160 m depth interval in the spring and to the 80–120 m depth interval in the fall. Clear evidence for nocturnal vertical migration was only seen in the spring at the 1-nm station (10-m depth interval tows were taken in the upper 100 m at this shallow-water station). Highest abundances were recorded between 60 and 30 m during the day to 30 m to the surface at night.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of sea snail
Sea snail
Sea snail is a common name for those snails that normally live in saltwater, marine gastropod molluscs....
, a holoplankton
Holoplankton
Holoplankton are organisms that are planktonic for their entire life cycle. Examples of holoplankton include some diatoms, radiolarians, some dinoflagellates, foraminifera, amphipods, krill, copepods, and salps.-Sources:Asexual Holoplankton:...
ic 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 mollusk in the 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...
Atlantidae
Atlantidae
Atlantidae is a family of sea snails, holoplanktonic gastropod molluscs in the clade Littorinimorpha.According to taxonomy of the Gastropoda by Bouchet & Rocroi the family Atlantidae has no subfamilies.- Description :...
.
Description
The maximal shell size of Atlanta lesueurii appears to vary geographically (from 2 mm in Hawaiian and eastern Australian waters to 6 mm in the tropical western Pacific). The shellGastropod 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...
is transparent, thin and fragile, with a smooth surface (lacking raised sculpture
Sculpture (mollusc)
The sculpture of a mollusc shell is the three-dimensional ornamentation on the outer surface, as distinct from the basic shape of the shell itself or colouration. Sculpture may be concave as well as convex. Sometimes it has microscopic detail. Sculpture refers to the calcareous outer layer, not the...
). The 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...
is very small, somewhat elevated and compact, consisting of about 2½ whorls. Spire sutures are deep, with the result that the whorls are somewhat rounded in profile and can easily be distinguished. After metamorphosis the outermost whorl enlarges and inflates rapidly and the keel becomes progressively taller, becoming very tall in large adults and having a truncate leading edge. The keel base and spire sutures are colorless.
Main features for the recognition of this species are the 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...
composed of just 2¼-3 convex 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...
, separated by an incised suture and the absence of any ornament. The first teleoconch whorl expands rapidly and bears a well-developed flange-like keel. In the largest specimens the final three quarters of the teleoconch separates from the penultimate whorl.
Eyes are type b, with a large lens. 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...
is the type b. Radula
Radula
The radula is an anatomical structure that is used by molluscs for feeding, sometimes compared rather inaccurately to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food enters the esophagus...
is type I, with a narrowly triangular shape.
Atlanta lesueurii is the large species in the genus Atlanta, but Atlanta peronii
Atlanta peronii
Atlanta peronii is a species of sea snail, a holoplanktonic marine gastropod mollusk in the family Atlantidae....
is larger.
Atlanta lesueurii resembles closely Atlanta oligogyra
Atlanta oligogyra
Atlanta oligogyra is a species of sea snail, a holoplanktonic marine gastropod mollusk in the family Atlantidae....
, in which, however, the first whorls are separated by a superficial suture and the shell remains much smaller.
Overview of description:
- Maximal shell size appears to vary geographically, between 2 and 6 mm
- Shell transparent with a thin, fragile walls
- Shell surface smooth; lacking surface sculpture
- Spire compact, consisting of about 2½ whorls
- Spire sutures incised, enabling distinction of whorls
- Keel tall, with a truncate leading edge
- Eyes type b; lens large
- Operculum type b
- Radula type I, narrowly triangular shape
Distribution
Atlanta lesueuri has a Recent circumglobal tropical/subtropical distribution.The first fossil specimens of Atlanta lesueurii has been found from Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...
in Tiep, Roxas
Roxas
Roxas various by language: Roahaas , Roahous , Rohan , Rohanna , Rojo , Roja Red , Rocksas , Rocksberry, Roxbury, Roxberry, Rowhous , Rosas , Roxburg , Roxburghe , Roxborough , Rocshire , Roxshire , Rochas and Rocha , Roach , Roashan Places in the Philippines:* Pres. Manuel A...
(map) and Anda, Pangasinan
Anda, Pangasinan
Anda is a 4th class island-municipality in the province of Pangasinan, Philippines. The people of Anda generally speak Bolinao. The island is near the Hundred Islands, a popular tourist destination for its caves and beaches....
, Luzon, Philippines in 2001 (published in 2007).
Ecology
Vertical distribution in Hawaiian waters is restricted to upper 150 m, with most individuals in the upper 100 m and some evidence for nocturnal migration into the upper 50 m.Vertical migration
Diel vertical distributionDiel vertical migration
Diel vertical migration, also known as diurnal vertical migration, is a pattern of movement that some organisms living in the ocean and in lakes undertake each day. Usually organisms move up to the epipelagic zone at night and return to the mesopelagic zone of the oceans or to the hypolimnion zone...
patterns of Atlanta lesueurii (among the 13 species of heteropods in the study) were investigated off leeward Oahu
Oahu
Oahu or Oahu , known as "The Gathering Place", is the third largest of the Hawaiian Islands and most populous of the islands in the U.S. state of Hawaii. The state capital Honolulu is located on the southeast coast...
, Hawaii in waters overlying a bottom depth of 2,000 m (between 9 and 11 km offthe coast) by Seapy (1990). Heteropods were collected during day and night periods using paired, opening-closing BONGO nets at 50-m depth intervals between the surface and 200 m and at 200–300 m and 300–400 m. Three or four replicated tows were taken in each depth interval. Atlanta lesueurii was found to be the most abundant species, with a maximal density of 59 individuals per 1,000 m3 in a daytime 0–45 m depth interval. The species ranged from the surface to 140 m during both day and night periods. There was an apparent partial populational migration from a depth interval of 45–90 m during the day to 0–45 m at night. However, high variability in densities between the replicated tows in each of the depth intervals resulted in statistically non-significant differences between day and night periods for each of the depth intervals.
In a subsequent study off leeward Oahu (Seapy, 2008), duplicate tows were taken with a MOCNESS multiple, opening-closing net system during day and night periods at three stations located 1, 5 and 15 nm off the island in fall and spring sampling periods. Mean densities were computed (as numbers of individuals beneath 100 m2 of ocean surface) during day and night periods at each station. As in the 1990 study, Atlanta lesueurii was the most abundant species in the fall, although it was a close second to Atlanta plana
Atlanta plana
Atlanta plana is a species of sea snail, a holoplanktonic marine gastropod mollusk in the family Atlantidae....
in the spring. Comparisons were made using the nighttime density data to avoid issues such as daytime net avoidance and to include increased nighttime abundances resulting from possible nocturnal vertical migrator species. Atlanta lesueurii was found to be most abundant at the offshore (15 nm) station during both seasons. Offshore to inshore abundance decreased most dramatically in the fall; from mean nighttime densities of 480 (15 nm) to 124 (5 nm) to 37 (1 nm) individuals beneath 100 m2 of ocean surface. At the 15 nm station the species ranged downward to the greatest depths; to the 120–160 m depth interval in the spring and to the 80–120 m depth interval in the fall. Clear evidence for nocturnal vertical migration was only seen in the spring at the 1-nm station (10-m depth interval tows were taken in the upper 100 m at this shallow-water station). Highest abundances were recorded between 60 and 30 m during the day to 30 m to the surface at night.