| Atlanta echinogyra | |
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| Apical view of the shell of Atlanta cf. echinogyra from the Pliocene of Philippines. Notice the flange-like keel. | |
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| Species: | A. echinogyra |
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| Atlanta echinogyra Richter, 1972 [2] | |
Atlanta echinogyra is a species of sea snail, a holoplanktonic marine gastropod mollusk in the family Atlantidae. [3]
Atlanta echinogyra was described in 1972 by Dr. Gotthard Richter (from Senckenberg Museum, Frankfurt am Main, Germany) based on specimens collected during the Meteor Expedition to the northern Indian Ocean. [4] Richter named the species after the unique structure of the opercular gyre, with its raised spiral row of spines. [4]
Atlanta echinogyra is a small species (to 2.5 mm shell diameter). [4] The shell is colorless, although the tissues underlying the shell spire give it a red-violet to red-brown color. [4] The spire is low conical and consists of 3-3.25 whorls. [1] [4] The spire whorls have incised sutures and bear low spiral ridges on the second through most of the fourth whorls. [4] The outer edge of the third and fourth whorls have a raised ridge (seen best in the larval shell). [4] The fourth whorl (first teleoconch whorl) increases rapidly in width and bears a flange-like keel. [1] The keel is moderately elevated with a slightly truncate leading edge. [4] The keel does not insert between the last two shell whorls. [4] The keel base is either clear or brown. [4] The early whorls are covered with a distinct and relatively coarse ornament consisting of four spirals. [1] 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. [1]
Eyes are type a. [4] Operculum is type c, with a gyre that bears a raised spiral row of strong, distally-tapering spines (hence the specific epithet, "echinogyra"). [4] Radula is type I, with unlimited numbers of tooth rows and lacking sexual dimorphism. [4]
Description overview:
Geographic distribution of Atlanta echinogyra is Indo-Pacific. [4]
In the plankton samples from the Meteor Expedition studied by Richter (1974), Atlanta echinogyra was the fourth most abundant species of heteropod (accounting for 9.1% of the total). [4] 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). [4] 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. [4] In eastern Australian waters, Newman (1990) recorded Atlanta echinogyra as rare in northern and central Great Barrier Reef waters. [4] Thus, it would appear that in the Pacific and Indian Oceans, Atlanta echinogyra is only abundant in the northern Indian Ocean. [4]
Atlanta cf. echinogyra is known from the Pliocene of Anda, Pangasinan, Luzon, Philippines. [1]
Vertical distribution limited to the upper 100 m in Hawaiian waters. [4]
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 ammonites.
The gastropod shell is part of the body of a gastropod or snail, a kind of mollusc. The shell is an exoskeleton, which protects from predators, mechanical damage, and dehydration, but also serves for muscle attachment and calcium storage. Some gastropods appear shell-less (slugs) but may have a remnant within the mantle, or the shell is reduced such that the body cannot be retracted within (semi-slug). Some snails also possess an operculum that seals the opening of the shell, known as the aperture, which provides further protection. The study of mollusc shells is known as conchology. The biological study of gastropods, and other molluscs in general, is malacology. Shell morphology terms vary by species group. An excellent source for terminology of the gastropod shell is "How to Know the Eastern Land Snails" by John B. Burch now freely available at the Hathi Trust Digital Library.
Atlantidae is a family of sea snails, holoplanktonic gastropod molluscs in the clade Littorinimorpha.
Atlanta is a genus of pelagic marine gastropod molluscs in the family Atlantidae. They are sometimes called heteropods.
The Pterotracheoidea is, according to the Taxonomy of the Gastropoda, a taxonomic superfamily of sea snails or sea slugs, marine gastropod molluscs in the clade Littorinimorpha. They are commonly called heteropods or sea elephants.
The following is a glossary of common English language and scientific terms used in the description of gastropods.
Teretiopsis thaumastopsis is a species of sea snail, a marine gastropod mollusk in the family Raphitomidae.
Cryptogemma polystephanus is a species of sea snail, a marine gastropod mollusk in the family Turridae, the turrids.
Choristella leptalea is a species of sea snail, a marine gastropod mollusk in the family Choristellidae.
Carenzia trispinosa is a species of sea snail, a marine gastropod mollusk in the family Seguenziidae.
Nucella lamellosa, commonly known as the frilled dogwinkle or wrinkled purple whelk, is a species of sea snail, a marine gastropod mollusk in the family Muricidae, the murex snails or rock snails. This species occurs in the eastern Pacific Ocean, its range extending in the intertidal zone from the Aleutian Islands southward to central California.
Atlanta brunnea is a species of sea snail, a holoplanktonic marine gastropod mollusk in the family Atlantidae.
Atlanta californiensis is a species of sea snail, a holoplanktonic marine gastropod mollusk in the family Atlantidae.
Atlanta lesueurii is a species of sea snail, a holoplanktonic marine gastropod mollusk in the family Atlantidae.
Oxygyrus keraudrenii is a species of sea snail, a holoplanktonic marine gastropod mollusk in the family Atlantidae.
Protatlanta souleyeti is a species of sea snail, a holoplanktonic marine gastropod mollusk in the family Atlantidae.
Protatlanta rotundata is an extinct species of sea snail, a holoplanktonic marine gastropod mollusk in the family Atlantidae.
Odostomia cooperi is a species of sea snail, a marine gastropod mollusk in the family Pyramidellidae, the pyrams and their allies.
Seguenzia costulifera is a species of extremely small deep water sea snail, a marine gastropod mollusk in the family Seguenziidae.
Carinaria cristata, commonly known as the glassy nautilus, is a species of pelagic marine gastropod mollusc in the family Carinariidae. It is found in the Pacific Ocean and is described as being holoplanktonic, because it spends its entire life as part of the plankton. It was first described by Carl Linnaeus in 1767. Its fragile shell was much prized by early conchologists for their collections, being so rare that it was said to be worth more than its weight in gold.
This article incorporates CC-BY-3.0 text from references. [1] [4]