If blue heron can consume 2 mussels per hour but require exp

If blue heron can consume 2 mussels per hour but require exposed mussels and a croaker can consume one mussel per hour but requires 0.5 m of water to swim, which is the greater predator?Explain why.

Solution

If the blue heron consumes exposed mussels, the mussels should most probably be dead. So the blue heron is not truly a predator but a saprophyte feeding off the dead exposed mussels.

In contrast, the croaker, which is habitually a coastal fish and thus is natural to be in shallow waters can find ample of shallow depths in the sea water to fish catch the mussels. It is a true predator hunting a live prey.

So, the croaker is a greater predator than the blue heron.