Some unusual species
The blobfish (Psychrolutes marcidus) is a deep sea fish, grow up to 30 centimetres, found off the coasts of mainland Australia and Tasmania. They live at depths of up to 800m and are rarely seen by humans.
Blobfish live at depths where the pressure is 80 times higher then normal sea level.The flesh of the blobfish is primarily a gelatinous mass with a density slightly less than water; this allows the fish to float above the sea floor without using energy to swim. Its lack of muscle is not a disadvantage as it primarily swallows prey that floats in front of it.
Blobfish arecaught by bottom trawling with nets as bycatch. Trawling in the waters off Australia may threaten the blobfish in what may be its only habitat and is currently facing extinction due to deep-sea fishing.
17 species of cladorhizid sponges, have been identified in New Zealand waters. Their biology is quite unique. They are often very small and feather or dandelion-shaped, and often completely lack the filtering systems used by all other sponges. Hook-like spicules cover the outside of the sponge filaments, rather like sticky Velcro. These hooks passively capture tiny invertebrate prey, such as crustaceans, that brush against them. When the crustacean is stuck, the cells of the sponge stream toward the prey to engulf its flesh, digesting it within individual cells. The filaments contract as the cells migrate toward the meal; when the dinner is complete; the filaments grow and extend again for the next meal, a process that can take 3 to 8 days.
From Beware the carnivorous sponge - CenSeam: a global census of marine life... http://www.niwa.co.nz/news-and-publications/publications/all/wa/14-1/...
Usually corals and sponges dominate seamount peaks, filtering food that arrives on the current. Biologists aboard the Tangaroa discovered “Brittlestar City” in the Maquarie Ridge (this stretches 1,400 km south from New Zealand to just above the Antarctic Circle). Brittlestar City is the first dense aggregation of another filter feeder, the brittlestar, ever found atop a seamount, and they credit the summit’s shape and extraordinary current circumstances there, 750-meters above the ocean floor. Reearchers photographed brown-black brittlestars numbering hundreds per square metre and estimate tens of millions of them populate the 100 square km flat top of the seamount.
Bubblegum Coral (Paragorgia arborea)
Bubblegum corals have eight tentacles on each polyp. They belonging to the phylum Cnidaria, which also includes stony corals and jellyfish and form colonies that feed on plankton and drifting organic particles. They have two types of polyp: large polyps with eight tentacles that are usually concentrated in dispersed clusters, and numerous tiny reproductive polyps without tentacles that are distributed throughout the colony surface. ‘Bubblegum’ alludes to the distinctive colour and surface appearance of the colony. It can form great branching trees that reach metres from the seabed.
Many animals are known to use red tree corals as both food and habitat. Economically important rockfish, shrimp and crabs hide among the branches, seeking protection. Crinoids, basket stars, anemones and sponges attach themselves to dead branches so they may better collect food from the currents. Other animals, such as sea stars and snails, feed directly on the corals themselves.