Diloma coracinum facts for kids
Quick facts for kids Diloma coracinum |
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| Drawing of a shell of Diloma coracinum | |
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Diloma coracinum is a type of small sea snail. It is a marine gastropod mollusc that belongs to the family Trochidae, also known as top snails. In the Māori language, this snail is called māihi.
About the Shell
The shell of Diloma coracinum is usually between 6 mm and 9 mm tall. Its width, or diameter, is between 8.5 mm and 12 mm. This small shell is solid and does not have a hole (imperforate). It has a shape that looks like a flattened cone or a round, depressed ball. The shell does not shine; it is lustreless. This species is quite varied in its appearance. It is also the smallest Diloma snail found in New Zealand.
Shell Features
The shell has faint spiral lines, which sometimes disappear. It also has growth lines that cross these spirals.
The shell's color is usually purplish-black or black. It can be a solid color or have a few yellow dots, especially on its bottom part.
The outer layer of the shell is strong and does not wear away easily. The top part of the shell, called the spire, is low and rounded. The very tip of the spire, the apex, is also rounded. The first two turns of the shell, called the protoconch, are flat and slightly curved. They have fine spiral lines and clear growth lines.
The shell has 4 to 5 turns, or whorls, which are slightly curved. The largest turn, called the body whorl, is big. It curves inward below the suture (the line where the turns meet). The edge of the body whorl is slightly angled. The front part of the shell, near the opening, can be worn away. The bottom of the shell is gently curved. The suture line is thin and has a small, wide ridge below it.
The opening of the shell, called the aperture, is slanted. Inside, it looks reddish and shiny, with lines. The outer lip of the opening is curved and sharp. It has a black edge inside, followed by a white band. This white band continues as a shiny stripe over the umbilical area, which is next to the columella (the central pillar of the shell). This stripe connects the ends of the opening. The umbilical area is bordered by green, gray, or brown colors.
The snail has a round, light brown, tough cover called an operculum. This cover has many spirals that start from its center.
Where They Live
This sea snail lives only in New Zealand. It is found around the coasts of the two biggest main islands. You can most often find Diloma coracinum on exposed southern or west coast shores.
