File:Trails made by variable coquina clams (Donax variabilis) (Cayo Costa Island, Florida, USA) 11 (25981995931).jpg
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DescriptionTrails made by variable coquina clams (Donax variabilis) (Cayo Costa Island, Florida, USA) 11 (25981995931).jpg |
Variable coquina clam trails in Florida, USA. (December 2012) Bivalves are bilaterally symmetrical molluscs having two calcareous, asymmetrical shells (valves) - they include the clams, oysters, and scallops. In most bivalves, the two shells are mirror images of each other (the major exception is the oysters). They occur in marine, estuarine, and freshwater environments. Bivalves are also known as pelecypods and lamellibranchiates. Bivalves are sessile, benthic organisms - they occur on or below substrates. Most of them are filter-feeders, using siphons to bring in water, filter the water for tiny particles of food, then expel the used water. The majority of bivalves are infaunal - they burrow into unlithified sediments. In hard substrate environments, some forms make borings, in which the bivalve lives. Some groups are hard substrate encrusters, using a mineral cement to attach to rocks, shells, or wood. The fossil record of bivalves is Cambrian to Recent. They are especially common in the post-Paleozoic fossil record. Shown above are many curvilinear trails in a supratidal sandy marine shoreline environment. Prima facie, these were suspected to be worm trails, but they were actually made by variable coquina clams, Donax variabilis. This clam species has a smooth, small, Tellina-like shell that varies considerably in color (hence the species name). It is common in shallow marine sandy environments, ranging from the intertidal zone to moderately shallow subtidal settings. The individuals that made these trails were in the supratidal part of a sandy marine shoreline. They likely reached this area during a then-recent storm, which usually results in a temporarily high sea level (storm surge). After the storm, the clams found themselves in a non-permanently wet or moist environment and made trails in search of water before dying. Variable coquina clams can be abundant in intertidal zone sandy beach environments of southwestern Florida. When the sand is disturbed (pick up a couple handfuls in the swash zone and place it back down), many Donax are often visible - they immediately burrow back down into the sediments. Classification: Animalia, Mollusca, Bivalvia, Heterodonta, Veneroida, Donacidae Locality: supratidal zone of marine beach near the southern end of the western shoreline of Cayo Costa Island, Gulf of Mexico coast of southwestern Florida, USA (vicinity of 26° 36' 51.30" North latitude, 82° 13' 24.39" West longitude) More info. at: en.wikipedia.org/wiki/Donax_variabilis |
Date | |
Source | Trails made by variable coquina clams (Donax variabilis) (Cayo Costa Island, Florida, USA) 11 |
Author | James St. John |
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This image was originally posted to Flickr by James St. John at https://flickr.com/photos/47445767@N05/25981995931. It was reviewed on 14 August 2016 by FlickreviewR and was confirmed to be licensed under the terms of the cc-by-2.0. |
14 August 2016
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current | 17:34, 14 August 2016 | 4,000 × 3,000 (4.38 MB) | Ser Amantio di Nicolao (talk | contribs) | Transferred from Flickr via Flickr2Commons |
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Camera manufacturer | Canon |
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Camera model | Canon PowerShot D10 |
Exposure time | 1/250 sec (0.004) |
F-number | f/9 |
ISO speed rating | 80 |
Date and time of data generation | 15:50, 17 December 2012 |
Lens focal length | 7.23 mm |
Image title | |
Width | 4,000 px |
Height | 3,000 px |
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Pixel composition | RGB |
Orientation | Normal |
Number of components | 3 |
Horizontal resolution | 180 dpi |
Vertical resolution | 180 dpi |
Software used | Adobe Photoshop Elements 13.0 (Macintosh) |
File change date and time | 23:48, 24 March 2016 |
Y and C positioning | Co-sited |
Exif version | 2.21 |
Date and time of digitizing | 15:50, 17 December 2012 |
Meaning of each component |
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Image compression mode | 2 |
APEX shutter speed | 7.96875 |
APEX aperture | 6.34375 |
APEX exposure bias | −0.33333333333333 |
Maximum land aperture | 3.34375 APEX (f/3.19) |
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Focal plane resolution unit | inches |
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File source | Digital still camera |
Custom image processing | Normal process |
Exposure mode | Manual exposure |
White balance | Manual white balance |
Digital zoom ratio | 1 |
Scene capture type | Standard |
Lens used | 6.2-18.6 mm |
Date metadata was last modified | 17:48, 24 March 2016 |
Unique ID of original document | D2DFC925A47E4A9148CB3484B8AD2003 |