Question

Which of the following bivalves is/are swimmers?

• A. Aspergillum
• B. Lima
• C. Tellina
• D. Pecten

Hint:

Remember that most bivalves are sessile or burrowers, but families like Limidae (\textit{Lima}) and Pectinidae (\textit{Pecten}) are notable exceptions because they can swim by valve clapping.

Answer 1

The Correct Option is B, D

Step 1: General concept.
Most bivalves are sedentary and either burrow in sediment or attach themselves to hard substrates. However, a few are capable of active swimming using rapid valve clapping or jetting water. These swimming bivalves usually belong to families like Pectinidae and Limidae. Step 2: Evaluate each option.
- (A) \textit{Aspergillum:}
Commonly known as the "watering pot shell," it is sedentary and lives in burrows within calcareous substrates. It is not capable of swimming. $\Rightarrow$ Incorrect.
- (B) \textit{Lima:}
Members of the Limidae family (file shells) such as \textit{Lima} are capable of swimming by rapidly clapping their valves and using tentacles for movement. $\Rightarrow$ Correct.
- (C) \textit{Tellina:}
These are burrowing bivalves that live in sandy or muddy bottoms. They are infaunal and not swimmers. $\Rightarrow$ Incorrect.
- (D) \textit{Pecten:}
Scallops (\textit{Pecten}) are well-known for their ability to swim by clapping their shells and generating jet propulsion. $\Rightarrow$ Correct.
Step 3: Final Answer.
The swimming bivalves among the given options are: \[ \boxed{\text{(B) \textit{Lima} and (D) \textit{Pecten}}} \]