Basking shark and Mackerel shark

Basking shark noun - Large harmless plankton-eating northern shark; often swims slowly or floats at the sea surface.

Mackerel shark and basking shark are semantically related. In some cases you can use "Mackerel shark" instead a noun phrase "Basking shark".

Mackerel shark noun - Fierce pelagic and oceanic sharks.

Basking shark and mackerel shark are semantically related. Sometimes you can replace phrase "Basking shark" with "Mackerel shark", this phrases are similar.