Question:medium
Which one of the following is a nektonic bivalve?
Which one of the following is a nektonic bivalve?
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Nektonic bivalves like Solen can swim actively, unlike benthic forms like Mytilus, Trigonia, and Gryphaea.
Updated On: Jun 1, 2026
- Gryphaea
- Trigonia
- Mytilus
- Solen
Show Solution
The Correct Option is D
Solution and Explanation
Step 1: What nektonic means.
Nektonic animals swim actively in the water and can move against a current. This is different from animals that sit on or in the sea floor.
Step 2: Check Gryphaea and Trigonia.
Gryphaea, the devils toenail, rested on the bottom and did not swim. Trigonia was also a bottom dweller. Neither is nektonic.
Step 3: Check Mytilus.
Mytilus, the common mussel, fixes itself to rock with thread like byssus. Being anchored, it is not a swimmer.
Step 4: Check Solen.
Solen, the razor clam, uses its strong foot to push and dart through water and sediment. Among the four it best fits the active, nektonic style.
Step 5: Final choice.
So the answer is Solen.
\[ \boxed{\text{Solen}} \]
Nektonic animals swim actively in the water and can move against a current. This is different from animals that sit on or in the sea floor.
Step 2: Check Gryphaea and Trigonia.
Gryphaea, the devils toenail, rested on the bottom and did not swim. Trigonia was also a bottom dweller. Neither is nektonic.
Step 3: Check Mytilus.
Mytilus, the common mussel, fixes itself to rock with thread like byssus. Being anchored, it is not a swimmer.
Step 4: Check Solen.
Solen, the razor clam, uses its strong foot to push and dart through water and sediment. Among the four it best fits the active, nektonic style.
Step 5: Final choice.
So the answer is Solen.
\[ \boxed{\text{Solen}} \]
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