(Note 2: First, please view the attached Comic.jpg file shown below or open it separately, before reading the detailed explanation below. A family member was able to correctly interpret most of it without any prior knowledge of the subject.)
(Please view the comic before reading)
The comic illustrates the cooperative hunting relationship of groupers and moray eels. When the grouper's prey is hiding in crevices that it cannot reach (1&2), it will signal to a moray eel to join the hunt, by shaking/shivering its body (3).
The grouper will also do a "headstand" and shake/shiver its body to point out the location of hidden prey to the moray eel (4). This will usually prompt the moray eel to investigate the indicated spot (5). Sometimes it will flush the prey out into the open, where the grouper can grab it (6). However, it's not always a fruitless hunt for the moray eel, because sometimes it will catch the prey first (7&8).
Neither fish is actively "sharing" prey with the other, each is simply trying to grab whatever prey it can catch. Although both are behaving selfishly, the cooperative hunting relationship benefits both parties, hence it is an example of mutualism. Together, the two predators cut off most of the prey's escape routes: swimming away or hiding in the reef. Thus, they can increase their success rates when hunting together.
Also, this relationship features a rare example of inter-species communication. The grouper uses specific gestures to communicate, which the moray eel is able to interpret. So far, moray eels have not been observed to signal back.
Grouper: fast swimmer, good eyesight, too big to pursue prey into hiding places in the reef
Moray Eel: slower, poor eyesight but good sense of smell, flexible and able to wriggle into small crevices
References (last accessed 13 Jul 2020):
Comic drawn using various online and book photographs as visual references, without tracing.
BONUS SECTION: Perhaps you could consider broadening to the topic to include relationships other than mutualism.
You can see wonders in the oceans
If you examine closely holothurians
The sea cucumber anus
Is really quite spacious
Enough to house commensal crustaceans