It seems that everything that has evolved to survive the ocean depth looks like an alien. A great example is the organism shown above: a scary scaleworm (Polychaete). This bizarre worm has a mouth that turns inside-out to help them in capturing their prey. This organism, which is a couple of inches long, lives in an ecosystem that was unknown until 40 years ago. Scientists are absolutely astonished about the diversity of creatures that live on and around hydrothermal vents. These "smokers" are cracks in the seafloor that form at the edges of tectonic plates, allowing geothermal fluids and gases to escape through the vents. Organisms live off the chemicals released from the vents. Scientists are studying this ecosystem to not only better understand our planet's biodiversity, but to also learn what to look for on other planets and their moons that also have hydrothermal vents, such as those that are believed to exist on Jupiter's moon Europa. There are over 10,000 species of scaleworm species, all but 168 (2 percent) that live in marine environments. Very few species ever evolved to live in fresh water.
How about the photo of an intriguing crab (I think) shown below? This image came from a web page written in another language, so I don't know anything about this creature that is so ugly -- it is cute.
Here is another awesome deep sea crab.
This distant relative of the hermit crab was discovered in 2005. It is not only a new genus and species of crab, but also represents a newer and more advanced family. Researchers speculate that the crabs may house bacteria in their bristles, where the bacteria reproduce and provide a steady source of crab food. The bacteria may also serve to detoxify poisonous compounds, such as sulfur, emitted in the vent fluids. Or the bacteria may convert sulfide compounds into food in exchange for a place to live on the crab. Additional specimens of crab will have to be studied to establish the relationship between the crab and its resident bacteria. There are nearly 7,000 species of crab on earth, with around 90 percent that live in the ocean and the remainder that live on land or in fresh water.
Pink Sea-Through Sea Cucumber
This incredibly translucent organism lets everything show. This pink see-through fantasia is found a mile and a half deep in the western Pacific (east of Borneo). There are around 1,250 species of Sea Cucumbers, with the greatest number being in the Asia Pacific region. One unusual feature of these animals is the material that forms their body wall. This collagen body surface can be loosened and tightened at will. IF the organism wants to squeeze through a small gap, it can essentially liquefy its body and pour into the space. To keep itself safe in these crevices and cracks, the sea cucumber will then reactivate and hook up all its collagen fibers to make its body firm again. In the ocean depths below five miles, sea cucumbers make up more than 90 percent of the biomass.
Found in the Celebes Sea, this is a squidworm. This is a brand new species (and a new genus) of worm just discovered in 2007. Since then five new species have been discovered. They live above the ocean floor and eat a mixture of sinking microscopic plants and animals, fecal material and cast-off mucus. Swimming upright, it navigates by moving two body-length rows of thin, paddle-shaped protrusions that cascade like dominoes.
This simple organism lives in a very complex arrangement as a colony composed of a number of specialised zooids linked together by a long stem. At the front is the pneumatophore, there is an orange-coloured, gas-filled float. Behind this area is a region where there are a number of translucent radial canals. These are bell-shaped medusae specialised for locomotion. When they contract, water is expelled which causes the colony to move. Their contractions are coordinated which enables the animal to swim forwards, sidewards or backwards. The remaining region of the colony includes polyps that function to collect food. They do this for the whole colony, spreading their single long tentacles in the water to snare prey.
Flamingo tongue snail
Jellyfish are found in every ocean, and at every depth.. A few jellyfish have even evolved to inhabit freshwater. Large, often colorful, jellyfish are common in coastal zones worldwide. Jellyfish have roamed the seas for at least 500 million years and possibly 700 million years or more, making them the oldest multi-organ animal on our planet. The main bell varies in size from species to species between a fraction of an inch to over six feet. There are over 200 different types of jellyfish.