Overview

Brief Summary

Introduction

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 shell is transparent, thin and fragile, with a smooth surface (lacking raised sculpture). The spire is very small, somewhat elevated and compact, consisting of about 2-1/2 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. Eyes type b, with a large lens. Operculum type b. Radula type I, with a narrowly triangular shape; largest in the genus Atlanta. Geographic distribution is cosmopolitan in tropical to subtropical waters. Vertical distribution in Hawaiian waters restricted to upper 150 m, with most individuals in the upper 100 m and some evidence for nocturnal migration into the upper 50 m.

Diagnosis

  • 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, comprised of about 2-1/2 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

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Comprehensive Description

Characteristics

  1. Shell
    1. Maximal shell size appears to vary geographically (=6 mm in the western tropical Pacific [Souleyet, 1852], 4 mm in the North Atlantic and Indian Oceans [Richter, 1986, 1974] and 2 mm off Hawaii [Seapy, 1990a,b] and eastern Australia [Newman, 1990]).
    2. Shell transparent with thin walls and keel
    3. Shell surface smooth, lacking raised sculpture on the spire whorls
    4. Spire very small, compact and somewhat elevated, consisting of about 2-1/2 whorls; spire whorls somewhat rounded and distinct from each other due to deep sutures (see fourth SEM image below)
    5. Keel tall, with a truncate leading edge (see first SEM image below)

      Figure. Scanning electron micrographs of a 1.2 mm Atlanta lesueurii, viewed from the right side (upper left), the shell spire (upper right), the right side tilted (lower left), and the spire tilted (lower right). Scale bars = 0.5 mm (upper and lower left) and 100 µm (upper and lower right). © Roger R. Seapy

  2. Coloration: in Hawaiian waters juveniles lack body coloration (see second title illustration), but with growth the spire tissues take on pink (see first title illustration) to pinkish-violet (see photograph below) coloration

    Figure. Specimen of a male Atlanta lesueurii retracted into its shell. Note the pinkish-violet coloration of the spire tissues. Shell diameter = 1.5 mm. © Roger R. Seapy

  3. Eyes type b, with a large lens (see first title illustration; also, in enlarged view the transverse slit in the distal pigmented tissue of the right eye can be discerned)
  4. Operculum type b; thin
  5. Radula type I; largest in the genus Atlanta
    1. Shape triangular
    2. Lateral teeth monocuspid (Richter, 1961)
    3. Number of tooth rows can exceed 100 in older adults (Richter and Seapy, 1999)

Comments

Diel vertical distribution 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 (1990b). 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. A. 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. at a station ). 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 mutiple, 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 1990b study, A. lesueurii was the most abundant species in the fall, although it was a close second to A. 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. A. 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 intervai 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.

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Ecology

Habitat

Depth range based on 5 specimens in 1 taxon.
Water temperature and chemistry ranges based on 2 samples.

Environmental ranges
  Depth range (m): 5 - 4766
  Temperature range (°C): 13.628 - 28.240
  Nitrate (umol/L): 2.050 - 4.457
  Salinity (PPS): 35.075 - 38.715
  Oxygen (ml/l): 4.102 - 4.395
  Phosphate (umol/l): 0.153 - 0.512
  Silicate (umol/l): 3.908 - 8.077

Graphical representation

Depth range (m): 5 - 4766

Temperature range (°C): 13.628 - 28.240

Nitrate (umol/L): 2.050 - 4.457

Salinity (PPS): 35.075 - 38.715

Oxygen (ml/l): 4.102 - 4.395

Phosphate (umol/l): 0.153 - 0.512

Silicate (umol/l): 3.908 - 8.077
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Wikipedia

Atlanta lesueurii

Atlanta lesueurii is a species of sea snail, a holoplanktonic marine gastropod mollusk in the family Atlantidae.[4]

Description[edit]

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).[5] The shell 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.[5] Spire sutures are deep, with the result that the whorls are somewhat rounded in profile and can easily be distinguished.[5] 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.[5] The keel base and spire sutures are colorless.[5]

apical view of the detail of the shell of Atlanta lesueurii shows clearly visible protoconch, that has 2¼ whorls

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.[1] The first teleoconch whorl expands rapidly and bears a well-developed flange-like keel.[1] In the largest specimens the final three quarters of the teleoconch separates from the penultimate whorl.[1]

Eyes are type b, with a large lens.[5] The Operculum is the type b.[5] Radula is type I, with a narrowly triangular shape.[5]

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.[1]

Overview of description:

  • Maximal shell size appears to vary geographically, between 2 and 6 mm[5][6]
  • Shell transparent with a thin, fragile walls[5]
  • Shell surface smooth; lacking surface sculpture[5]
  • Spire compact, consisting of about 2½ whorls[5]
  • Spire sutures incised, enabling distinction of whorls[5]
  • Keel tall, with a truncate leading edge[5]
  • Eyes type b; lens large[5]
  • Operculum type b[5]
  • Radula type I, narrowly triangular shape[5]

Distribution[edit]

Atlanta lesueuri has a Recent circumglobal tropical/subtropical distribution.[1]

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).[1]

Ecology[edit]

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.[5]

Vertical migration[edit]

Diel vertical distribution 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).[5] 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.[5] Three or four replicated tows were taken in each depth interval.[5] 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.[5] The species ranged from the surface to 140 m during both day and night periods.[5] There was an apparent partial populational migration from a depth interval of 45–90 m during the day to 0–45 m at night.[5] 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.[5]

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.[5] Mean densities were computed (as numbers of individuals beneath 100 m2 of ocean surface) during day and night periods at each station.[5] 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.[5] 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.[5] Atlanta lesueurii was found to be most abundant at the offshore (15 nm) station during both seasons.[5] 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.[5] 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.[5] 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).[5] Highest abundances were recorded between 60 and 30 m during the day to 30 m to the surface at night.[5]

References[edit]

This article incorporates CC-BY-3.0 text from references.[1][5]

  1. ^ a b c d e f g h Janssen A. W. (2007). "Holoplanktonic Mollusca (Gastropoda: Pterotracheoidea, Janthinoidea, Thecosomata and Gymnosomata) from the Pliocene of Pangasinan (Luzon, Philippines)". Scripta Geologica 135. 
  2. ^ Gray J. E. (1850). Catalogue of the Mollusca in the collection of the British Museum, 2. Pteropoda. British Museum and E. Newman, London: iv + 45 pp.
  3. ^ (French) Souleyet F. L. A. (1852). In: Eydoux, [F.] & Souleyet, [F.L.A.] Voyage autour du monde exécuté pendant les années 1836 et 1837 sur la corvette ‘La Bonite’, commandée par M. Vaillant, capitaine de vaisseau, publié par ordre du Gouvernement sous les auspices du département de la marine. Zoologie, 2. Mollusques; Ptéropodes: 37-392, atlas (undated): pls 4-15, 15bis, 16-23, 23bis, 24, 24bis. A. Bertrand, Paris. Atlanta lesueurii is on the page 380, plate 20. figs. 1-8.
  4. ^ a b Atlanta lesueurii J. E. Gray, 1850. WoRMS (2010). Atlanta lesueurii J. E. Gray, 1850. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=430416 on 14 August 2010.
  5. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai Seapy R. R. (2009). Atlanta lesueurii Gray 1850. Atlanta lesueuri Souleyet 1852. Version 29 October 2009. http://tolweb.org/Atlanta_lesueurii/28765/2009.10.29 in The Tree of Life Web Project, accessed 20 August 2010.
  6. ^ Welch J. J. (2010). "The "Island Rule" and Deep-Sea Gastropods: Re-Examining the Evidence". PLoS ONE 5(1): e8776. doi:10.1371/journal.pone.0008776.
Creative Commons Attribution Share Alike 3.0 (CC BY-SA 3.0)

Source: Wikipedia

Unreviewed

Article rating from 0 people

Default rating: 2.5 of 5

Disclaimer

EOL content is automatically assembled from many different content providers. As a result, from time to time you may find pages on EOL that are confusing.

To request an improvement, please leave a comment on the page. Thank you!