Open main menu

Opengenome.net β

Changes

Copepod

12,578 bytes added, 16:46, 30 September 2006
no edit summary
<p><strong>Copepods</strong> are a group of small <a title="Crustacean" href="http://en.wikipedia.org/wiki/Crustacean">crustaceans</a> found in the sea and nearly every <a title="Fresh water" href="http://en.wikipedia.org/wiki/Fresh_water">freshwater</a> <a title="Habitat (ecology)" href="http://en.wikipedia.org/wiki/Habitat_%28ecology%29">habitat</a>. Many species are <a title="Plankton" href="http://en.wikipedia.org/wiki/Plankton">planktonic</a>, but more are <a title="Benthos" href="http://en.wikipedia.org/wiki/Benthos">benthic</a>, and some continental species may live in limno-terrestrial habitats and other wet terrestrial places, such as swamps, under leaf fall in wet forests, bogs, springs, ephemeral ponds and puddles, damp moss, or water-filled recesses (phytothelmata) of plants such as <a title="Bromeliad" href="http://en.wikipedia.org/wiki/Bromeliad">bromeliads</a> and <a title="Pitcher plant" href="http://en.wikipedia.org/wiki/Pitcher_plant">pitcher plants</a>. Many live underground in marine and freshwater caves, <a title="Sinkhole" href="http://en.wikipedia.org/wiki/Sinkhole">sinkholes</a>, or stream beds. Some copepods are <a title="Parasite" href="http://en.wikipedia.org/wiki/Parasite">parasitic</a> and attach themselves to fish, sharks, marine mammals, and many kinds of invertebrates such as molluscs, tunicates, or corals.</p>
<p>Planktonic copepods are hugely important to global <a title="Ecology" href="http://en.wikipedia.org/wiki/Ecology">ecology</a> and the <a class="new" title="Carbon balance" href="http://en.wikipedia.org/w/index.php?title=Carbon_balance&amp;action=edit">carbon balance</a>; They are usually the dominant members of the <a title="Zooplankton" href="http://en.wikipedia.org/wiki/Zooplankton">zooplankton</a>, and are major food organisms for small <a title="Fish" href="http://en.wikipedia.org/wiki/Fish">fish</a>, <a title="Whale" href="http://en.wikipedia.org/wiki/Whale">whales</a>, <a title="Seabird" href="http://en.wikipedia.org/wiki/Seabird">seabirds</a> and other <a title="Crustacean" href="http://en.wikipedia.org/wiki/Crustacean">crustaceans</a> such as <a title="Krill" href="http://en.wikipedia.org/wiki/Krill">krill</a> in the ocean and in fresh water. Some scientists say they form the largest animal <a title="Biomass" href="http://en.wikipedia.org/wiki/Biomass">biomass</a> on earth. They compete for this title with <a title="Antarctic krill" href="http://en.wikipedia.org/wiki/Antarctic_krill">Antarctic krill</a> (<em>Euphausia superba</em>). Because of their smaller size and relatively faster growth rates, however, and because they are more evenly distributed throughout more of the world's oceans, copepods almost certainly contribute far more to the <a class="new" title="Secondary productivity" href="http://en.wikipedia.org/w/index.php?title=Secondary_productivity&amp;action=edit">secondary productivity</a> of the world's oceans, and to the global ocean <a title="Carbon sink" href="http://en.wikipedia.org/wiki/Carbon_sink">carbon sink</a> than <a title="Krill" href="http://en.wikipedia.org/wiki/Krill">krill</a>, and perhaps than all other groups of organisms together. The surface layers of the oceans are currently believed to be the world's largest <a title="Carbon sink" href="http://en.wikipedia.org/wiki/Carbon_sink">carbon sink</a>, absorbing about 2 billion tonnes of carbon a year, the equivalent to perhaps a third of <a title="Greenhouse gas" href="http://en.wikipedia.org/wiki/Greenhouse_gas">human carbon emissions</a>, thus reducing their impact. Many <a title="Plankton" href="http://en.wikipedia.org/wiki/Plankton">planktonic</a> copepods feed near the surface at night, then sink into deeper water during the day. Their moulted <a title="Exoskeleton" href="http://en.wikipedia.org/wiki/Exoskeleton">exoskeletons</a>, <a title="Feces" href="http://en.wikipedia.org/wiki/Feces">faecal</a> pellets and <a title="Respiration" href="http://en.wikipedia.org/wiki/Respiration">respiration</a> at depth all bring <a title="Carbon" href="http://en.wikipedia.org/wiki/Carbon">carbon</a> to the deep sea.</p>
<p>Copepods are typically <a title="1 E-3 m" href="http://en.wikipedia.org/wiki/1_E-3_m">1-2&nbsp;mm</a> long, with a teardrop shaped body and large <a title="Antennae" href="http://en.wikipedia.org/wiki/Antennae">antennae</a>. Although like other <a title="Crustacean" href="http://en.wikipedia.org/wiki/Crustacean">crustaceans</a> they have an armoured <a title="Exoskeleton" href="http://en.wikipedia.org/wiki/Exoskeleton">exoskeleton</a>, they are so small that in most species this armour, and the entire body, is almost totally transparent. Copepods have a single eye, usually bright red and in the centre of the transparent head. Some polar copepods reach 1&nbsp;<a title="Centimetre" href="http://en.wikipedia.org/wiki/Centimetre">cm</a>. Most of the smaller copepods feed directly on <a title="Phytoplankton" href="http://en.wikipedia.org/wiki/Phytoplankton">phytoplankton</a>, catching cells singly, but a few of the larger species are predators of their smaller relatives. Herbivorous copepods, particularly those in rich cold seas, store up energy from their food as oil droplets while they feed in the spring and summer <a class="new" title="Plankton bloom" href="http://en.wikipedia.org/w/index.php?title=Plankton_bloom&amp;action=edit">plankton blooms</a>. These droplets may take up over half of the volume of the body in polar species.</p>
<p>Copepods form a <a title="Subclass (biology)" href="http://en.wikipedia.org/wiki/Subclass_%28biology%29">subclass</a> belonging to the subphylum <a title="Crustacea" href="http://en.wikipedia.org/wiki/Crustacea">Crustacea</a> (crustaceans). Some authors consider the copepods to be a full <a title="Class (biology)" href="http://en.wikipedia.org/wiki/Class_%28biology%29">class</a>. The group contains ten <a title="Order (biology)" href="http://en.wikipedia.org/wiki/Order_%28biology%29">orders</a> with some 14,000 described <a title="Species" href="http://en.wikipedia.org/wiki/Species">species</a>. A scientist that studies copepods is a <em>copepodologist</em>.</p>
<p>Copepods are sometimes found in the public mains water supply, especially systems where the water is not filtered, such as <a title="New York City" href="http://en.wikipedia.org/wiki/New_York_City">New York City</a> and <a title="Boston, Massachusetts" href="http://en.wikipedia.org/wiki/Boston%2C_Massachusetts">Boston, Massachusetts</a>. This is not usually a problem in treated water supplies. In some tropical countries, such as <a title="Peru" href="http://en.wikipedia.org/wiki/Peru">Peru</a> and <a title="Bangladesh" href="http://en.wikipedia.org/wiki/Bangladesh">Bangladesh</a>, a correlation has been found between copepods and <a title="Cholera" href="http://en.wikipedia.org/wiki/Cholera">cholera</a> in untreated water, because the cholera bacteria attach to the surfaces of planktonic animals. The risk of cholera from infected water can be reduced by filtering out the copepods (and other matter), for example with a <a title="Cloth filter" href="http://en.wikipedia.org/wiki/Cloth_filter">cloth filter</a>.</p>
<div class="thumb tleft">
<div style="WIDTH: 182px"><a class="internal" title="Copepods from Ernst Haeckel's Kunstformen der Natur" href="http://en.wikipedia.org/wiki/Image:Haeckel_Copepoda.jpg"><img height="253" alt="Copepods from Ernst Haeckel's Kunstformen der Natur" src="http://upload.wikimedia.org/wikipedia/commons/thumb/9/97/Haeckel_Copepoda.jpg/180px-Haeckel_Copepoda.jpg" width="180" longdesc="/wiki/Image:Haeckel_Copepoda.jpg" /></a>
<div class="thumbcaption">
<div class="magnify" style="FLOAT: right"><a class="internal" title="Enlarge" href="http://en.wikipedia.org/wiki/Image:Haeckel_Copepoda.jpg"><img height="11" alt="Enlarge" src="http://en.wikipedia.org/skins-1.5/common/images/magnify-clip.png" width="15" /></a></div>
Copepods from <a title="Ernst Haeckel" href="http://en.wikipedia.org/wiki/Ernst_Haeckel">Ernst Haeckel</a>'s <em><a title="Kunstformen der Natur" href="http://en.wikipedia.org/wiki/Kunstformen_der_Natur">Kunstformen der Natur</a></em></div>
</div>
</div>
<p>Many species have neurons surrounded by <a title="Myelin" href="http://en.wikipedia.org/wiki/Myelin">myelin</a>, which is very rare among <a title="Invertebrate" href="http://en.wikipedia.org/wiki/Invertebrate">invertebrates</a> (other examples are some <a title="Annelid" href="http://en.wikipedia.org/wiki/Annelid">annelids</a> and <a title="Malacostraca" href="http://en.wikipedia.org/wiki/Malacostraca">malacostracan</a> crustaceans like <a class="new" title="Palaemonidae" href="http://en.wikipedia.org/w/index.php?title=Palaemonidae&amp;action=edit">palaemonid</a> shrimp and <a title="Penaeid" href="http://en.wikipedia.org/wiki/Penaeid">penaeids</a>). Even rarer is the fact that the myelin is highly organized, resembling the well-organized wrapping found in vertebrates (<a title="Gnathostomata" href="http://en.wikipedia.org/wiki/Gnathostomata">Gnathostomata</a>).</p>
<p>Some copepods are very evasive and can jump with extreme speed over a few millimeters (warning: takes some time to load to the correct speed):</p>
<div class="thumb tright">
<div style="WIDTH: 322px"><a class="internal" title="Slow-motion macrophotography video (50%) of juvenile Atlantic herring (38 mm) feeding on copepods - the fish approach from below and catch each copepod individually. In the middle of the image a copepod escapes successfully to the left." href="http://en.wikipedia.org/wiki/Image:Cc3s.gif"><img height="240" alt="Slow-motion macrophotography video (50%) of juvenile Atlantic herring (38 mm) feeding on copepods - the fish approach from below and catch each copepod individually. In the middle of the image a copepod escapes successfully to the left." src="http://upload.wikimedia.org/wikipedia/en/3/3e/Cc3s.gif" width="320" longdesc="/wiki/Image:Cc3s.gif" /></a>
<div class="thumbcaption">Slow-motion macrophotography video (50%) of juvenile <a title="Atlantic herring" href="http://en.wikipedia.org/wiki/Atlantic_herring">Atlantic herring</a> (38 mm) feeding on copepods - the fish approach from below and catch each copepod individually. In the middle of the image a copepod escapes successfully to the left.</div>
</div>
</div>
<p>This scene was scanned with the <a title="EcoSCOPE" href="http://en.wikipedia.org/wiki/EcoSCOPE">ecoSCOPE</a>, an underwater high speed microscope. Very little is known about the details of these kinds of predator/prey interactions, in spite of their importance for global processes, because copepods are difficult to keep in the laboratory and lose most of their escape capacity, and herring are very fast, alert and evasive organisms and flee normal camera systems or <a title="Scuba diving" href="http://en.wikipedia.org/wiki/Scuba_diving">scuba divers</a>.</p>
<p>For the use of copepods as <a title="Bioindicator" href="http://en.wikipedia.org/wiki/Bioindicator">bioindicators</a>, see <a title="Particle (ecology)" href="http://en.wikipedia.org/wiki/Particle_%28ecology%29">particle (ecology)</a>.</p>
<div class="editsection" style="FLOAT: right; MARGIN-LEFT: 5px">[<a title="Edit section: External links" href="http://en.wikipedia.org/w/index.php?title=Copepod&amp;action=edit&amp;section=1">edit</a>]</div>
<p><a id="External_links" name="External_links"></a></p>
<h2>External links</h2>
<ul lastcheckbox="null">
<li><a class="external text" title="http://copepodes.obs-banyuls.fr/en/" href="http://copepodes.obs-banyuls.fr/en/">Diversity and geographical distribution of pelagic copepoda</a> </li>
<li><a class="external text" title="http://www.uwm.edu/~jrs/COPEPODS%20CENTRAL.htm" href="http://www.uwm.edu/~jrs/COPEPODS%20CENTRAL.htm">Rudi Strickler copepod videos</a> </li>
<li><a class="external text" title="http://jaffeweb.ucsd.edu/pages/celeste/copepods.html" href="http://jaffeweb.ucsd.edu/pages/celeste/copepods.html">The virtual copepod page</a> </li>
<li><a class="external text" title="http://www.nmnh.si.edu/iz/copepod/" href="http://www.nmnh.si.edu/iz/copepod/">Copepod World</a> </li>
<li><a class="external text" title="http://www.nsf.gov/od/lpa/forum/colwell/rc01_anatlesson/tsld024.htm" href="http://www.nsf.gov/od/lpa/forum/colwell/rc01_anatlesson/tsld024.htm">Copepods and cholera in untreated water</a> </li>
<li><a class="external text" title="http://www.kosherwater.com/reprints.htm" href="http://www.kosherwater.com/reprints.htm">CNN report: New York Times: The Water's Fine, but Is It Kosher?</a> </li>
</ul>
Anonymous user