Whorl

The term "whorl" refers to a structural feature rather than a specific type of animal.

In zoology, a whorl is a single, complete 360° revolution or turn in the spiral or whorled growth of a mollusc shell.

A mollusc's shell, which can exhibit whorls, is a hard exoskeleton that serves to protect and support the mollusc's body.

It is largely composed of calcium carbonate secreted by the mantle, a skin-like tissue in the mollusk’s body wall.

The shell's coiled form approximates an equiangular spiral or variations of it, providing both strength and compactness.

In summary, a whorl is part of the shell structure of certain molluscs, which are invertebrate animals with soft bodies, most of which are enclosed in a calcium carbonate shell.

A spiral shell can be found in many gastropods (such as snails and slugs) and some cephalopods (such as nautilus and ammonites).

Some shells have many whorls, while others have fewer than two.

Whorls can be counted by drawing a line from the nucleus (the first whorl) to the margin of the shell, and following the course of the whorl until it is parallel to the starting position.

Whorls are important for identifying and classifying different types of molluscs.

• A circular arrangement of like parts, such as leaves, flowers, or ridges, around a point on an axis. For example, some plants have whorls of petals or leaves that radiate from the stem.

• A single turn of a spiral shell, such as a snail or a mollusk. The body whorl is the most recently formed and largest whorl of a spiral shell, ending in the opening.

• A flywheel or a disc-shaped object that is fitted onto a spindle to increase and maintain the speed of the spin. For example, some spinning or weaving machines have whorls on their spindles.

• A fingerprint pattern in which the central ridges on the skin turn through at least one complete circle. Whorls are one of the main types of fingerprint patterns, along with loops and arches.

• Plants: A whorl is a group of leaves, flowers, or other organs that are arranged around a point on a stem. For example, some lilies have whorled leaves.

• Animals: A whorl is a turn of the shell of a snail or other univalve mollusk. For example, the garden snail has four to five whorls in its shell.

• Fingerprints: A whorl is a type of fingerprint pattern that has at least one complete circle of ridges on the skin. For example, about 30% of human fingerprints are whorls.

• Art: A whorl is a shape that resembles a coil or a swirl. For example, some abstract paintings use whorls to create visual effects.