Jellyfish

Jellyfish appear for the first time as enemies in underwater levels.

Crash Bandicoot: The Wrath of Cortex
Crash must avoid them or he will be electrocuted. They can only be destroyed by missiles from the submarine or Aku Aku invincibility for they could shock from far distances. They mimic the classic 'Frogger Style' movement seen throughout the Crash series. (Ex. The seal line from the snow-themed levels in Crash Bandicoot 2: Cortex Strikes Back and the skunk lines from the jungle-themed levels in Crash Bandicoot.) They will continuously file out of the abyss and the player is forced to either quickly maneuver the submarine over the jellyfish before they completely barricade the player or blast a hole through the jellyfish line and move through.

Crash Bandicoot: The Huge Adventure
They reappear in this game. However, in this game, they can be spun from the bottom.

Physiology
Judging by the size of the jellyfish in the game, they seem to be Lion's Mane Jellyfish (Cyanea capillata), the largest known species of jellyfish known to exist. The actually anatomy of the jellyfish is very simple and cartoonish, similar to the "Blue Jellyfish" from the Spongebob Squarepants series. These jellyfish give off a blue bio-luminescence, similar to the light of Ctenophora.

Habitat
The only known location of jellyfish in the Crash games is deep in caverns on the bottom of the ocean floor, like in the level Coral Canyon. Their 'Frogger' movement indicates that there can be an infinite number of jellyfish in one undersea cavern. The cavern itself glows a light blue, similar to the bio-luminescence given off by the jellyfish, another, more practical indication that there are many more jellyfish down in the cavern.