As they submerge to the deep ocean bottom, marine scientists might encounter any number of bizarre-looking organisms, illuminated in their submersible's headlights. These photos are a few of the deep-sea dwellers that UD marine scientists have seen en route to vent sites 2 miles down.
While few deep-sea fish live at hydrothermal vent sites -- with the exception of pale eel-like zoarcids, also known as eelpouts -- fish have been found at great depths elsewhere in the ocean. How low can they go? The greatest depth at which a fish has been recorded is 27,460 feet. That's more than 5 miles deep!
Fangtooth. Food is scarce in the deep sea. The fish that live here must rely on what little food floats down from above--referred to as "marine snow"--or eat their neighbors! Deep-sea fish typically have big mouths, long sharp teeth, and stretchy stomachs to catch prey in the dark and swallow it whole. This fish, called "fangtooth," is found at depths of 2,600 to 5,000 feet. It grows to about 10 inches long.
Tubeworms. Resembling giant lipsticks, these worms live over a mile deep on the Pacific Ocean floor near hydrothermal vents. This species, Riftia pachyptila, may grow to about 8 feet tall. Tubeworms have no mouth, eyes, or stomach. They get their energy from bacteria that live inside their bodies. These bacteria convert the chemicals that spew out of the vent into food for the worms.]
Deep-Sea Dragonfish. Since there, is no natural light in the ocean below 3,300 feet, many deep-sea fish rely on bioluminescent (light-producing) organs to find a mate and lure prey. The dragonfish has a long chin barbel that glows in the dark. The fish uses the barbel like a fishing lure, flashing it on and off and waving it back and forth. When an unsuspecting fish nears, it is snapped up in the dragonfish's powerful jaws. While this fish grows to only about 6 inches long, it is a fierce predator.
Deep-Sea Octopus. Hair-like projections called "cirri" line the webbed arms of this octopus. These projections may help it sense food in the darkness. This species is also equipped with paddle-like fins to help it swim.