a scientist is observing an invertebrate animal that she collected in shallow salt water. The animas has a hollow central cavity and a gut. which animal is the xcientist most likely observing?

The scientist is viweing cnidarian, because it has gut.

Explanation:

The gastrovascular gut is the essential organ of assimilation and dissemination in two noteworthy creature phyla: the Cnidaria (counting jellyfish and corals) and Platyhelminthes (flatworms). The cavity might be broadly spread into an arrangement of channels.

In cnidarians, the gastrovascular framework is otherwise called the coelenteron, and is usually known as a "visually impaired gut" or "visually impaired sac", since nourishment enters and waste exits through a similar hole.