Deep Water pelagic fish

In the open sea beyond the continental shelf, five life zones can be recognized. In the euphotic or epipelagic zone (the first 500 feet below the sea surface) cyanobacteria and phytoplankters receive enough light for photosynthesis. These tiny organisms are the primary producers of the entire pelagic regions. Beneath this zone, consumers either feed on sinking algae and bacteria, are scavengers of the rain of organic debris coming from above, or are predators of the other consumers. All life in the pelagic region either drifts or must swim in the water column all of the time.

At depths greater than 3, 500 ft below sea level, the pelagic habitat is fairly uniform and dark. Pressure increases with increasing depth, which poses problems for body structure and buoyancy, but an even bigger challenge is limited food availability. Species have evolved to meet these challenges, but biodiversity is relatively low.

In the epipelagic zone, tiny zooplankters consume the one-celled phytoplankters larger, and zooplankters rely upon globs of particulate organic matter (POM) known as “marine snow.” At night the zooplankters rise toward the surface to feed on algae and bacteria. Most predators, both invertebrate (e.g., copepods) and vertebrate (e.g. fishes) also feed at night. Many of the carnivores hunt by sight, so natural selection has favored “invisible” zooplankters—transparent gelatinous creatures such as salps (planktonic tunicates), siphonophores, medusae (jellyfish), ctenophores (com jellies), squids, and chaetognaths (arrow worms). Fish typically are counter-shaded (dark on top; light on the undersides) and have disruptive patterns that make them less visible to predators from below; still they are safer feeding in night-time darkness when their prey is more concentrated.

In the mesopelagic zone, the same groups dominate as in the epipelagic zone, but different species occur: copepods and siphonophores are especially abundant. Shrimp in this region of the sea are often transparent and red or orange, pigments that absorb the shorter wavelengths of sunlight that penetrate into this zone, rendering them more or less invisible to predators.

Fish in the upper parts of this zone are strongly muscled, usually have well-developed eyes, dark backs, reflective flanks, and light-producing organs (photophores) on their bellies. Gas-filled swim bladders help them control buoyancy. Predators tend to have upward-oriented eyes and mouths. Fishes in the lower parts of the zone are dark all over and do not have reflective flanks.

The highest diversity of pelagic organisms is found in the baythypelagic zone at depths between -3, 000 and -8, 000 ft. Fishes here are black and have tiny, simple eyes. They have fat-filled swim bladders or lake them altogether. Feather-like bristles and antennae may aid buoyancy. Bioluminescence is important in species and gender recognition, in luring prey, in spotlighting prey, and/or in confusing predators. Musculature is greatly reduced to save energy. Many fish look like a large mouth with fins.

The abyssopelagic zone, an area of immense pressure and constant cold (35°-37° F) is inhabited primarily by decapods and, in the deepest waters, by mysid shrimp.


Sea Frontiers 1974 Jan.- Feb. (Pelagic Adaptations, Artificial Reefs, freedom to fish, king of the winged boats, 20)
Book (american color plate)

Fish Stocks/ Windpower/ Wave Generators

2006-11-14 00:23:43 by jaybug39

I have read that ocean fish stocks will be gone in a few years. And I have been thinking since I heard that Massachusetts refused to build wind turbines in Long Island Sound as they were unattractive, why not build some in the pacific where we could create national sea life refuges?
This would help out coastal communities in several regards. Some people would come see the turbines, much like some people visit lighthouses. The energy produced would ease any difficulties coastal communities may face from their currently existing long distance power transmissions. And they would get the benefit of knowing that fish will be around in the future


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