AY Honors/Shells - Advanced/Answer Key

2006-06-28T14:23:16Z

67.54.224.62: Unicodifying using AWB

A '''whorl''' is a single, complete 360° turn in the [[spiral]] growth of a [[mollusc]] [[Animal shell|shell]]. A mollusc shell is basically a long tube, usually coiled in a spiral for strength and compactness. The number of whorls in the shell depend on various factors in the geometric growth, as described in work of [[D'Arcy Wentworth Thompson|D’Arcy Wentworth Thompson]] (''[[On Growth and Form]]'') and [[David Raup]].

The number of whorls differs in various groups, with the extant family [[Turritellidae]] and the [[Mesozoic]] family [[Nerineidae]] having very high [[Spire (mollusc)|spired]] shells with a large number of whorls and hence a relatively small [[Aperture (mollusc)|aperture]].

*'''Apical whorls'''—those whorls near the apex or tip of the shell.
*[[Body whorl]]—The most recently formed whorl of a spiral shell.
*'''Nuclear whorl(s)'''—small, generally smooth whorls formed within the egg and constituting the apex of the shell.
*'''[[Protoconch]]''' a larval shell of a mollusc; also refers to protoconch whorls of an adult shell.
*'''Teleoconch'''—all the whorls of a shell after the protoconch whorls.

[[Category:Animal anatomy]]
[[Category:Molluscs]]

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AY Honors/Shells - Advanced/Answer Key