Question

Apple snail is the common name of
(a) Turbinella
(b) Pila
(c) Cyprea
(d) Aplysia

Answer 1

Hint: It is a family of large freshwater snails that contains both gills and lungs with the mental cavity.

Complete answer:
Pila is the common name of Apple snail and it is a family of large freshwater snails and aquatic gastropod molluscs with a gill and an operculum in their body. This is in the superfamily Ampullariidae, class Gastropoda, and phylum Mollusca. The Ampullariidae has some unusual characteristics because they have both a gill and a lung, with the mantle cavity being divided in order to separate the two types of respiratory structures. This adaptation allows these snails to be amphibious. Pila species act as a host of a trematode.

Features of Apple snail:
- All molluscs are terrestrial or aquatic with an organ- system level of organization.
- They are bilaterally symmetrical, triploblastic and coelomate animals.
- The body of Pila is covered by a calcareous shell and is unsegmented with a distinct head, muscular foot and visceral hump.
- They are soft-bodied animals with a spirally coiled round shell.
- They have respiratory and excretory functions.
- The anterior head has sensory tentacles and the operculum is well developed.
- The mouth of molluscs contains a file like a rasping organ for feeding, called a radula.
- Mainly all molluscs are dioecious in nature and oviparous with indirect development.

Figure: Apple snail

So, the correct answer is Pila.

Note:
- Triploblastic means three embryonic layers such as ectoderm, mesoderm and endoderm present. - Coelomate animals have a true body cavity called a coelom.
- Trematodes are parasitic flatworms, known as flukes which are from phylum Platyhelminthes. Most trematodes have a complex life cycle with two hosts; molluscs and parasites. The secondary host is the molluscs.