This 3-foot jellyfish uses four to seven strong tentacles to capture its prey but has no stinging cells. It is so different from other known jellyfish that scientists created a new subfamily for it.

A cartoonish species of dumbo octopus found at depths ranging from 1,000 to 16,000 feet.

A vampire squid from hell, which has assumed its defensive "pineapple posture" by throwing its arms over its head.

A 20-inch glowing sucker octopus with fins that resemble elephant ears.

This small squid can change color and hue from virtually glass-clear to reddish. The large reflective spot under the eye bioluminesces to cancel out their shadow and make them invisible to predators lurking below.

A foot-long sea cucumber known as the deep-sea Spanish dancer. When the creature is attacked, its skin lights up and detaches, sticking to the aggressor.

Another deep-sea jellyfish.

Another little-known species of deep-sea dumbo octopus, the largest of which can reach 5-feet in length.

This bizarre-looking fish has large sensory pores around its mouth and lives more than 3,000 feet beneath the ocean surface.

Brightly colored 7-foot tube worms thrive near deep-sea hydrothermal vents and derive their energy from chemosynthetic bacteria.

The Johnson-Sea-Link submersible can dive 3,000 feet below the ocean surface offering panoramic views to its pilot and a paqssenger who sit within a clear acrylic sphere.

A ghostly 3-inch-long deep-sea white anglerfish. The buttonline lure between its eyes bioluminesces to attract prey.

A red paper lantern medusa jellyfish.

Almost completely transparent, this octopus drifts in the midwater waiting for prey.