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A shell-dwelling Lamprologus ocellatus. The terms shell dwellers or shelldwellers, shell-breeding, or ostracophil are descriptive terms for cichlid fish that use the empty shells of aquatic snails as sites for breeding and shelter. The terms have no taxonomic basis, although most shell-dwelling cichlids are from Lake Tanganyikas lamprologine ...
Shell intactness was the most critical factor, followed by shell length and aperture width. This approach disentangles the influence of different shell features, which are usually correlated in nature, and provides a more refined method for studying animal decision-making and niche construction.
Difflugia is the largest genus of Arcellinida, one of several groups of Tubulinea within the eukaryote supergroup Amoebozoa. [1] Arcellinida species produce shells or tests from mineral particles or biogenic elements (e.g. diatom frustules) and are thus commonly referred to as testate amoebae or shelled amoebae.
The shell ranges from 3 mm to 37 mm in diameter depending on species. Like in chitons , the head is poorly defined, and there are no eyes. The mouth is located within the animal's undeveloped head in front of its single large foot and contains a radula , a defining characteristic of the mollusca.
Umbilicated – Having an opening in the base of the shell. [1] Undulated – Having undulations or waves. [1] Univalve – Having the shell composed of a single piece, as a snail. [1] Varicose – Swollen or enlarged. [1] Vascular – Containing or made up of blood vessels. [1] Vermiform – Formed like a worm. [1] Ventral – The lower border ...
Four views of a shell of the land snail Arianta arbustorum The giant clam (Tridacna gigas) is the largest extant species of bivalve. The mantle is visible between the open valves. A mollusc shell is formed, repaired and maintained by a part of the anatomy called the mantle. Any injuries to or abnormal conditions of the mantle are usually ...
They were predominantly deposit-feeding bottom dwellers, although there is evidence to suggest that some species took to the water column to be free-swimming organisms. † Anaspida (extinct) Anaspida ('no-shields') is an extinct group of primitive jawless vertebrates that lived during the Silurian and Devonian periods. [16]
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 but may have a remnant within the mantle, or in some cases the shell is reduced such that the body cannot be retracted within it .