This MedLibrary.org supplementary page on Aphotic zone is provided directly from the open source Wikipedia as a service to our readers. Please see the note below on authorship of this content, as well as the Wikipedia usage guidelines. To search for other content from our encyclopedia supplement, please use the form below:
Related Sponsors
|
|
|
| Pelagic | |
| Photic | |
| Epipelagic | |
| Aphotic | |
| Mesopelagic | |
| Bathyalpelagic | |
| Abyssalpelagic | |
| Hadalpelagic | |
| Demersal | |
| Benthic | |
|
|
|
| Pycnocline | |
| Isopycnal | |
| Thermocline | |
| Halocline | |
| Chemocline | |
|
|
|
|
|
|
The aphotic zone (aphotic from Greek prefix ἀ- + φῶς "without light") is the portion of a lake or ocean where there is little or no sunlight.
It is formally defined as the depths beyond which less than 1% of sunlight penetrates. Consequently, bioluminescence is essentially the only light found in this zone. Most food comes from dead organisms sinking to the bottom of the lake or ocean from overlying waters.
The depth of the aphotic zone can be greatly affected by such things as turbidity and the season of the year. The aphotic zone underlies the photic zone, which is that portion of a lake or ocean directly affected by sunlight.
The Ocean
The aphotic zone of the ocean is 0.9 - 4.6 km (3,000 - 15,000 feet) deepcitation needed and the temperatures range from 0 - 6°C (32 - 43°F)citation needed. Unusual and unique creatures dwell in this expanse of pitch black water, such as the gulper eel, the giant squid, the anglerfish, and the vampire squid.
The aphotic zone is divided into two parts- the bathyal zone and the abyssal zone. The bathyal zone extends from 200 meterscitation needed to 2000 meters. The abyssal zone extends from 2000 meters to the bottom. Creatures in this area must be able to live in complete darkness.
See also
 This oceanography article is a stub. You can help Wikipedia by expanding it. |
Wikipedia content modification information:
- This page was last modified on 4 August 2008, at 23:30.
Wikipedia Authorship and Review
Wikipedia content provided here is not reviewed directly by MedLibrary.org. Wikipedia content is authored by an open community of volunteers and is not produced by or in any way affiliated with MedLibrary.org.
Wikipedia Usage Guidelines
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article on "Aphotic zone".
The URL for this specific entry is:
All Wikipedia text is available under the terms of the GNU Free Documentation License. (See Copyrights for details). Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc.