Atlanta echinogyra
Encyclopedia
Atlanta echinogyra is a species
of sea snail
, a holoplankton
ic marine
gastropod mollusk in the family
Atlantidae
.
, Frankfurt am Main, Germany) based on specimens collected during the Meteor Expedition to the northern Indian Ocean. Richter named the species after the unique structure of the opercular
gyre, with its raised spiral row of spines.
Atlanta echinogyra is a small species (to 2.5 mm shell diameter). The shell is colorless, although the tissues underlying the shell spire give it a red-violet to red-brown color. The spire is low conical and consists of 3-3.25 whorls
. The spire whorls have incised sutures and bear low spiral ridges on the second through most of the fourth whorls. The outer edge of the third and fourth whorls have a raised ridge (seen best in the larval shell). The fourth whorl (first teleoconch whorl) increases rapidly in width and bears a flange-like keel. The keel is moderately elevated with a slightly truncate leading edge. The keel does not insert between the last two shell whorls. The keel base is either clear or brown. The early whorls are covered with a distinct and relatively coarse ornament consisting of four spirals. This ornament is also visible on the base of the shell, where it is present in the umbilicus, on the last part of the protoconch.
Eyes are type a. Operculum is type c, with a gyre that bears a raised spiral row of strong, distally-tapering spines (hence the specific epithet, "echinogyra"). Radula
is type I, with unlimited numbers of tooth rows and lacking sexual dimorphism.
Description overview:
In the plankton samples from the Meteor Expedition studied by Ricther (1974), Atlanta echinogyra was the fourth most abundant species of heteropod (accounting for 9.1% of the total). By contrast, the species was uncommon off northeastern Australia (ranking ninth, accounting for 1.5% of the total number of heteropods collected) in a study by Seapy et al. (2003). In Hawaiian waters Atlanta echinogyra was variable in its presence and numbers among different collections, ranking eleventh out of thirteen species of atlantids (Seapy, 1990a); from five different sampling periods between 1984 and 1986, it was not collected twice, was represented by a single individual once, and by 27 and 19 individuals in two collections. In eastern Australian waters, Newman (1990) recorded Atlanta echinogyra as rare in northern and central Great Barrier Reef waters. Thus, it would appear that in the Pacific and Indian Oceans, Atlanta echinogyra is only abundant in the northern Indian Ocean.
of Anda, Pangasinan
, Luzon, Philippines.
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
Atlanta echinogyra was described in 1972 by Dr. Gotthard Richter (from Senckenberg MuseumSenckenberg Museum
The Naturmuseum Senckenberg in Frankfurt is the second largest museum of natural history in Germany. It is particularly popular with children, who enjoy the extensive collection of dinosaur skeletons: Senckenberg boasts the largest exhibition of large dinosaurs in Europe. One particular treasure is...
, Frankfurt am Main, Germany) based on specimens collected during the Meteor Expedition to the northern Indian Ocean. Richter named the species after the unique structure of the opercular
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...
gyre, with its raised spiral row of spines.
Atlanta echinogyra is a small species (to 2.5 mm shell diameter). The shell is colorless, although the tissues underlying the shell spire give it a red-violet to red-brown color. The spire is low conical and consists of 3-3.25 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...
. The spire whorls have incised sutures and bear low spiral ridges on the second through most of the fourth whorls. The outer edge of the third and fourth whorls have a raised ridge (seen best in the larval shell). The fourth whorl (first teleoconch whorl) increases rapidly in width and bears a flange-like keel. The keel is moderately elevated with a slightly truncate leading edge. The keel does not insert between the last two shell whorls. The keel base is either clear or brown. The early whorls are covered with a distinct and relatively coarse ornament consisting of four spirals. This ornament is also visible on the base of the shell, where it is present in the umbilicus, on the last part of the protoconch.
Eyes are type a. Operculum is type c, with a gyre that bears a raised spiral row of strong, distally-tapering spines (hence the specific epithet, "echinogyra"). 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 unlimited numbers of tooth rows and lacking sexual dimorphism.
Description overview:
- Shell small, with a maximal diameter of 2.5 mm elevated spiral row of outwardly-directed spines that taper distally
- Shell colorless
- Spire region of shell red-violet to red-brown due to underlying tissues
- Spire of 3-3/4 whorls, with low conical shape and deep sutures
- Low spiral ridges present on the second through most of the fourth spire whorls
- Outer edge of third and fourth whorls with a raised ridge
- Keel moderately elevated, with a slightly truncate leading edge
- Keel does not insert between last two whorls
- Keel base clear (North Pacific Ocean) or dark to yellow-brown (northern Indian Ocean)
- Eyes type a
- Operculum type c; gyre bears a raised spiral row of distally-tapering spines
- Radula type I
Distribution
Geographic distribution of Atlanta echinogyra is Indo-Pacific.In the plankton samples from the Meteor Expedition studied by Ricther (1974), Atlanta echinogyra was the fourth most abundant species of heteropod (accounting for 9.1% of the total). By contrast, the species was uncommon off northeastern Australia (ranking ninth, accounting for 1.5% of the total number of heteropods collected) in a study by Seapy et al. (2003). In Hawaiian waters Atlanta echinogyra was variable in its presence and numbers among different collections, ranking eleventh out of thirteen species of atlantids (Seapy, 1990a); from five different sampling periods between 1984 and 1986, it was not collected twice, was represented by a single individual once, and by 27 and 19 individuals in two collections. In eastern Australian waters, Newman (1990) recorded Atlanta echinogyra as rare in northern and central Great Barrier Reef waters. Thus, it would appear that in the Pacific and Indian Oceans, Atlanta echinogyra is only abundant in the northern Indian Ocean.
Fossil distribution
Atlanta cf. echinogyra is known from the PliocenePliocene
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...
of 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.