Aquariums often have some creative setups that put an extra spotlight on the fascinating sea life on display, such as spooky Halloween jellyfish exhibitions and tunnels that turn eels into good luck New Year's sushi rolls. However, it's always the natural behavior of the animals that resonates the most.

Japanese Twitter user Mai Otani (@maiohtanifiddle) captured that sentiment recently when they made a visit to the Maxell Aqua Park Shinagawa in Tokyo and was taken aback by a tank of zebra sharks.

One shark seems to be enjoying a nibble of one shark, and the other doesn't seem to mind at all:

Many in the comments were amused by what appears to be a very "I don't care, go ahead" expression on the shark being chewed on--especially when pressed up against the glass--but this may actually be part of a courtship ritual zebra sharks engage in, in which the male shark nibbles on the tail of the female shark. So Mai may have just had the luck of visiting at that exact moment!

By - grape Japan editorial staff.