Pila globosa (Apple Snail) - Diagram and Description

Pila globosa or apple snail are gastropod molluscs and thus their body shows coiling or torsion. They are freshwater organisms that can be found in ponds, lakes and streams. During the rainy season, they come out of ponds and thrive in the land. Also, it can overcome extreme drought with a period of inactivity by burying itself in the mud. This is called summer sleep or aestivation.

Let’s learn more about the habitat and description of Pila globosa with a well-labelled diagram.

Table of Contents:

• Pila globossa – Classification
• Labelled Diagram of Pila globosa or Apple Snail
• Habitat and Distribution
• Description
• Frequently Asked Questions

Pila globosa – Classification

Labelled Diagram of Pila globosa or Apple Snail

Habitat and Distribution

Pila is abundantly found in tanks, pools, ponds, streams and lakes. It is a freshwater mollusc and can also be found in brackish water environments with low salinity. They are amphibious and thus adapted to live both on land as well as on water. They are mostly confined to the Ethiopian and Oriental regions.

They are herbivores and feed on the plant scrapping and succulent aquatic vegetation.

Description

• Apple snails are found in various colours. They are typically globose in shape and are brown or lemon-yellow in colour.
• They are molluscs and thus have a soft and unsegmented body. Their body can be regionated into the head, visceral mass and foot.
• The head has two pairs of tentacles, one pair of eyes, a ventral slit-like mouth or aperture and nuchal lobes.
• In the shell, the outer margin of the aperture is called an outer lip, and the inner margin is called the columellar or inner lip.
• The foot is a broad, flat, ventral and roughly triangular structure attached to the operculum.
• Visceral mass is a hump-like structure containing the main organs. It fills the whorls of the shell and is also spirally coiled.
• The mantle covers the visceral mass. It forms a hood over the snail when it is withdrawn. The mantle has a pigmented chemosensory patch called the osphradium that typically tests the quality of water.
• Radula is present in the buccal mass.
• The animal is well-protected by a spirally twisted shell. Only the foot and head come out of the shell mouth. The visceral mass lies inside the whorls of the shell.
• The shell is coiled spirally to form the apex, body whorl and the penultimate whorl. Suture lines are present between the whorls. The shell shows right-hand or dextral coiling.
• The centre of the shell has a vertical axis around which the shell whorls are coiled. This vertical axis opens to the exterior as an umbilicus.
• The shell surface shows lines of growth called the varices.
• The unique feature of Pila is the presence of an operculum. Operculum is a calcareous anatomical structure which also has concentric lines of growth. When the snail is inside the shell, it is covered by this structure called an operculum.
• Pila respires with the help of the pulmonary sac and ctenidium (gills).
• It has a heart with the pericardium, and renal organs are also present.
• Sexes are separate, and fertilisation is internal.

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