Question

The presence of a sucking disc with 10-28 transverse movable laminae on the head is the striking taxonomic feature of which family ?

• A. Rachycentridae
• B. Echeneidae
• C. Catastomidae
• D. Sphyrnidae

Hint:

Remember: Remoras (Suckerfish) = Family Echeneidae, possessing a modified first dorsal fin on the head that forms a suction disc with transverse laminae.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Several fish species have developed specialized morphological adaptations to live in commensal or mutualistic relationships with larger marine hosts like sharks, turtles, and marine mammals.

Step 2: Detailed Explanation:
The family Echeneidae comprises the remoras or suckerfishes.
Their most striking taxonomic diagnostic feature is the presence of an oval, transversely laminated sucking disc located dorsally on the head.
This sucking disc is a highly modified first dorsal fin.
It contains between 10 to 28 transverse, movable cartilaginous plates (laminae) that can be raised or lowered to create a powerful vacuum.
This allows the remora to attach itself firmly to the skin of larger marine animals, obtaining free transportation, protection from predators, and access to food scraps from the host's meals.
Let us review the other families:
- Rachycentridae: Contains the cobia, which lacks a sucking disc.
- Catastomidae: Freshwater sucker fishes, but their "sucker" is a modified mouth, not a dorsal disc.
- Sphyrnidae: Hammerhead sharks, characterized by a laterally expanded head (cephalofoil).

Step 4: Final Answer:
Therefore, the family characterized by this dorsal sucking disc is Echeneidae.