shrimp, prawn, lobster
鰕 centers on aquatic crustaceans with shells and segmented bodies: shrimp, prawn, and lobster. The meanings are closely related as types of edible shellfish-like sea creatures.
鰕 combines 魚 (fish) with 叚, which likely contributes the sound. The character is used for shrimp and similar crustaceans, treated as a type of fish in traditional classification.
The left side 魚 means fish, and the right side 叚 looks like a shrimp's segmented body with legs. Together they make a fish-like creature that is actually a shrimp or prawn.
For カ, imagine a shrimp caught in a car's headlights: car -> カ, and the shrimp is the catch of the day.