Demersal fish
Most demersal fish exhibit a flat ventral region so as to more easily rest their body on the substrate.
They either lie-and-wait as ambush predators, at times covering themselves with sand or otherwise camouflaging themselves, or move actively over the bottom in search for food.
But as the fish grows from the larval stage, one eye migrates to the other side of the body as a process of metamorphosis.
Flounder ambush their prey, feeding at soft muddy area of the sea bottom, near bridge piles, docks, artificial and coral reefs.
The great hammerhead swings its head in broad angles over the sea floor to pick up the electrical signatures of stingrays buried in the sand.
For example, the family of nearly blind spiderfishes, common and widely distributed, feed on benthopelagic zooplankton.
Their fins have long rays they use to "stand" on the bottom while they face the current and grab zooplankton as it passes by.
[10] Following Moyle and Cech (2004) they can be divided into five overlapping body shapes:[10] Benthopelagic fish inhabit the water just above the bottom, feeding on benthos and zooplankton.
However, the energy demands of sharks are high, since they need to swim constantly and maintain a large amount of oil for buoyancy.
Deep sea stingrays are benthopelagic, and like the squaloids have very large livers which give them neutral buoyancy.
[17] An example of a flabby fish is the cusk-eel Acanthonus armatus,[18] a predator with a huge head and a body that is 90 per cent water.
This fish has the largest ears (otoliths) and the smallest brain in relation to its body size of all known vertebrates.
[19] Deepwater benthopelagic fish are robust, muscular swimmers that actively cruise the bottom searching for prey.
Coastal demersal fishes live on the bottom of inshore waters, such as bays and estuaries, and further out, on the floor of the continental shelf.
The term epibenthic is also used to refer to organism that live on top of the ocean floor, as opposed to those that burrow into the seafloor substrate.
They bury themselves in sand, and leap upwards to ambush benthopelagic fish and invertebrates that pass overhead.
Deep sea benthic fishes are more likely to associate with canyons or rock outcroppings among the plains, where invertebrate communities are established.
Undersea mountains (seamounts) can intercept deep sea currents, and cause productive upwellings which support benthic fish.
[28] Rattails and brotulas are common, and other well-established families are eels, eelpouts, hagfishes, greeneyes, batfishes and lumpfishes.
A consequence of these energy delivery mechanisms is that the abundance of demersal fish and invertebrates gradually decrease as the distance from continental shorelines increases.
[30] Although deep water demersal fish species are not generally picky about what they eat, there is still some degree of specialisation.
Cameras show that when a dead fish is placed on the bottom, vertebrate and invertebrate scavengers appear very quickly.
[31][34] At great depths, food scarcity and extreme pressure limits the ability of fish to survive.
Commercially important demersal food fish species include flatfish, such as flounder, sole, turbot, plaice, and halibut.
[42] Black sea bass inhabit US coasts from Maine to NE Florida and the eastern Gulf of Mexico, and are most abundant off the waters of New York.
They spend most of their time close to the sea floor and are often congregated around bottom formations such as rocks, man-made reefs, wrecks, jetties, piers, and bridge pilings.
There is some research indicating that roving coral groupers (Plectropomus pessuliferus) sometimes cooperate with giant morays in hunting.
[46] Deepwater benthopelagic fish are robust, muscular swimmers that actively cruise the bottom searching for prey.
[48][49] Major demersal fishery species in the North Sea such as cod, plaice, monkfish and sole, are listed by the ICES as "outside safe biological limits."
The European Commission has written that “A key issue is that many of the most important demersal stocks (i.e. those that live on or near the bottom of the sea) are caught in mixed fisheries.
