The Feeding of Deep Sea Fish and Invertebrates

The deep sea is completely absent of sunlight, and the pressure can approach up to 1100 atm (up to 1000 times our surface pressure).  The harsh abiotic factors of the deep sea has caused organisms to develop unique ways of attaining food, some of which are highlighted below.

These gulper eels have evolved to gain huge mouths and expandable stomachs, allowing them to engulf large amounts of food at one time. When rare opportunities, like a dead whale hitting the ocean floor, appear, fish with adaptions like the gulper eel can capitalize on the abundance of food.

Organisms like the deep sea sponge of the family Geodiidae have adapted to filter small food particles from the passing water, allowing them to live in most nutrient-starved habitats.

Some deep sea sponges' lack of dependence on sunlight helps them out-compete organisms that do depend on light, like coral. 

Some deep sea carnivorous sponges have been found.

Species like the anglerfish have become equipped with a long dorsal fin on their heads with a tipped bioluminescence glow to lure fish. Such an adaption means that fish like the anglerfish, such as the viperfish, don't have to expend large amounts of energy hunting for food in the extremely dense deep sea.

Lophophorates are organisms characterized by a special feeding organ called a lophophore, which is an extension of the body wall into a U-shaped or circular tentacled structure surronding the mouth. The lophophore is used to trap floating food particles in passing currents.

Organisms collect "marine snow," dead organic material that falls to the sea floor.

References:

marinebio.org 

http://www.montereybayaquarium.org/animals/AnimalDetails.aspx?enc=Z5SIVkZ+n+WJB8kogvD/1A==

http://marinebio.org/oceans/deep/

http://news.nationalgeographic.com/news/2010/07/photogalleries/100727-science-new-species-canada-deep-sea-newfoundland-pictures/

http://www.niwa.co.nz/news/three-new-and-astounding-deep-sea-sponges-with-carnivorous-ways

http://www.gma.org/fogm/Chauliodus_sloani.htm

http://www.youtube.com/watch?v=BW05vMziy2o

http://www.youtube.com/watch?v=Fo2J9kDQkKA

http://seavenger.info/gulper-eel/

http://www.geog.ubc.ca/biodiversity/efauna/LophophoratesABriefTaxonomy_000.html

By John McDonough and Anthony Sabitsky