Carnivorous protist

Predatory dinoflagellates are predatory heterotrophic or mixotrophic alveolate protists that derive some or most of their nutrients from digesting other organisms. About one half of dinoflagellates lack photosynthetic pigments and specialize in consuming other eukaryotic cells, and even photosynthetic forms are often predatory.cite book |author=Doyle, Jeff; Soltis, Douglas E.; Soltis, Pamela S. |title=Molecular systematics of plants II: DNA sequencing |publisher=Kluwer Academic Publishers |location=Boston |year=1998 |pages= |isbn=0-412-11121-7 |oclc= |doi=] cite book |author=Bhattacharya, Debashish; Olson, Laura Katz |title=Genomics and evolution of microbial eukaryotes |publisher=Oxford University Press |location=Oxford [Oxfordshire] |year=2006 |pages= |isbn=0-19-856974-2 |oclc= |doi=]

Organisms that derive their nutrition in this manner include "Oxyrrhis marina", which feeds phagocytically on phytoplanktoncite journal |author=Whiteley AS, Burkill PH, Sleigh MA |title=Rapid method for cell cycle analysis in a predatory marine dinoflagellate |journal=Cytometry |volume=14 |issue=8 |pages=909–15 |year=1993 |pmid=7507024 |doi=10.1002/cyto.990140809] , "Polykrikos kofoidii", which feeds on several species of red-tide and/or toxic dinoflagellatescite journal |author=Jeong HJ, Kim SK, Kim JS, Kim ST, Yoo YD, Yoon JY |title=Growth and grazing rates of the heterotrophic dinoflagellate Polykrikos kofoidii on red-tide and toxic dinoflagellates |journal=J. Eukaryot. Microbiol. |volume=48 |issue=3 |pages=298–308 |year=2001 |pmid=11411838 |doi=] , "Ceratium furca", which is primarily photosynthetic but also capable of ingesting other protists such as ciliatescite journal |author=Smalley GW, Coats DW |title=Ecology of the red-tide dinoflagellate Ceratium furca: distribution, mixotrophy, and grazing impact on ciliate populations of Chesapeake Bay |journal=J. Eukaryot. Microbiol. |volume=49 |issue=1 |pages=63–73 |year=2002 |pmid=11908900 |doi=] , "Cochlodinium polykrikoides", which feeds on phytoplanktoncite journal |author=Jeong HJ, Du Yoo Y, Kim JS, "et al" |title=Mixotrophy in the phototrophic harmful alga Cochlodinium polykrikoides (Dinophycean): prey species, the effects of prey concentration, and grazing impact |journal=J. Eukaryot. Microbiol. |volume=51 |issue=5 |pages=563–9 |year=2004 |pmid=15537091 |doi=] , "Gambierdiscus toxicus", which feeds on algae and produces a toxin that causes ciguatera fish poisoning when ingestedcite journal |author= |title=Ciguatera fish poisoning--Texas, 1998, and South Carolina, 2004 |journal=MMWR Morb. Mortal. Wkly. Rep. |volume=55 |issue=34 |pages=935–7 |year=2006 |pmid=16943762 |doi=] , and "Pfiesteria" and related species such as "Luciella masanensis", which feed on diverse prey including fish skin and human blood cells.cite journal |author=Vogelbein WK, Lovko VJ, Shields JD, "et al" |title=Pfiesteria shumwayae kills fish by micropredation not exotoxin secretion |journal=Nature |volume=418 |issue=6901 |pages=967–70 |year=2002 |pmid=12198545 |doi=10.1038/nature01008] cite journal |author=Jeong HJ, Ha JH, Yoo YD, "et al" |title=Feeding by the Pfiesteria-like heterotrophic dinoflagellate Luciella masanensis |journal=J. Eukaryot. Microbiol. |volume=54 |issue=3 |pages=231–41 |year=2007 |pmid=17552978 |doi=10.1111/j.1550-7408.2007.00259.x] Predatory dinoflagellates can kill their prey by releasing toxins or phagocytize small prey directly. [http://www3.interscience.wiley.com/cgi-bin/abstract/110427393/ABSTRACT]

Some predatory algae have evolved extreme survival strategies. For example, "Oxyrrhis marina" can turn cannibalistic on its own species when no suitable non-self prey is availablecite journal |author=Martel CM, Flynn KJ |title=Morphological controls on cannibalism in a planktonic marine phagotroph |journal=Protist |volume=159 |issue=1 |pages=41–51 |year=2008 |pmid=17768088 |doi=10.1016/j.protis.2007.05.003] , and "Pfiesteria" and related species have been discovered to kill and feed on fish, and since have been (mistakenly) referred to as carnivorous "algae" by the media.

Usage in the popular media

The media has applied the term carnivorous or predatory algae mainly to "Pfiesteria piscicida", "Pfiesteria shumwayae" and other "Pfiesteria"-like dinoflagellates implicated in harmful algal blooms and fish kills.cite web |url=http://atlas.aaas.org/index.php?part=2&sec=waste&sub=agchem |title=AAAS Atlas of Population and Environment |accessdate=2008-01-05 |format= |work=] cite book |author=Michael Greger |title=Bird Flu: A Virus of Our Own Hatching |publisher=Lantern Books |location= |year= |pages= |isbn=1-59056-098-1 |oclc= |doi= |URL=http://www.birdflubook.com/a.php?id=52] "Pfiesteria" as an "ambush predator" utilizes a "hit and run" feeding strategy by releasing a toxin that paralyzes the respiratory systems of susceptible fish, such as menhaden, thus causing death by suffocation. It then consumes the tissue sloughed off its dead prey.cite book |author=Eichhorn, Susan E.; Raven, Peter H.; Evert, Ray Franklin |title=Biology of plants |publisher=W.H. Freeman and Company |location=New York |year=2005 |pages=205 |isbn=0-7167-1007-2 |oclc= |doi=] "Pfiesteria piscicida" ( _la. fish killer) has been blamed for killing more than one billion fish in the Neuse and Pamlico river estuaries in North Carolina and causing skin lesions in humans in the 1990s. It has been described as "skinning fish alive to feed on their flesh" or chemically sensing fish and producing lethal toxins to kill their prey and feed off the decaying remains. Its deadly nature has led to "Pfiesteria" being referred to as "killer algae"cite web |url=http://www.cdnn.info/news/article/a020815.html |title=Cyber Diver News Network: Cell from Hell - Killer Algae Eating Fish |accessdate=2008-02-09 |format= |work=] cite web |url=http://discovermagazine.com/1993/apr/killeralgae198 |title=Killer Algae | Unusual Organisms | DISCOVER Magazine |accessdate=2008-02-09 |format= |work=] and has earned the organism the reputation as the "T. rex" of the dinoflagellate world"cite web |url=http://www.unc.edu/depts/cmse/science/pfiesteria.html |title=The Fuss Over Pfiesteria |accessdate=2008-01-05 |format= |work=] or "the Cell from Hell."cite journal |author=Morris JG |title=Pfiesteria, "the cell from hell," and other toxic algal nightmares |journal=Clin. Infect. Dis. |volume=28 |issue=6 |pages=1191–6; quiz 1197–8 |year=1999 |pmid=10451151 |doi=]

"Pfiesteria" hysteria"

The prominent and exaggerating media coverage of "Pfiesteria" as carnivorous algae attacking fish and humans has been implicated in causing "Pfiesteria" hysteria" in the Chesapeake Bay in 1997 resulting in an apparent outbreak of human illness in the Pocomoke region in Maryland.cite journal |author=Terlizzi DE |title=Pfiesteria Hysteria, Agriculture, and Water Quality in the Chesapeake Bay: The Extension Bridge over Troubled Waters |journal=Journal of Extension |volume=44 |issue=5 |pages=5FEA3 |year=2006 |pmid= |doi= |url=http://www.joe.org/joe/2006october/a3.shtml ] However, a study published the following year concluded the symptoms were unlikely to be caused by mass hysteria.cite journal |author=Greenberg DR, Tracy JK, Grattan LM |title=A critical review of the Pfiesteria hysteria hypothesis |journal=Md Med J |volume=47 |issue=3 |pages=133–6 |year=1998 |pmid=9601200 |doi=]

In popular culture

During the media coverage in the 1990s, "Pfiesteria" has been referred to as "super villain" and subsequently has been used as such in several fictional works. A "Pfiesteria" subspecies killing humans featured in James Powlik's 1999 environmental thriller "Sea Change". In Frank Schätzing's 2004 science fiction novel The Swarm, lobsters and crabs spread the killer alga "Pfiesteria homicida" to humans.

In Yann Martel's 2001 novel "Life of Pi", the protagonist encounters a floating island of carnivorous algae inhabited by meerkats while shipwrecked in the Pacific Ocean. At a book reading in Calgary, Canada, Martel explained that the carnivorous algae island had the purpose of representing the more fantastical of two competing stories in his novel and challenge the reader to a "leap of faith."cite web |url=http://www.ffwdweekly.com/Issues/2003/1120/book1.htm |title=FFWD Weekly - November 20, 2003 |accessdate=2008-01-05 |format= |work=]

In the 2005 National Geographic TV show "Extraterrestrial", the alien organism termed "Hysteria" combines characteristics of "Pfiesteria" with those of cellular slime molds. Like "Pfiesteria", "Hysteria" is a unicellular, microscopic predator capable of producing a paralytic toxin. Like cellular slime molds, it can release chemical stress signals that cause the cells to aggregate into a swarm which allows the newly formed superorganism to feed on much larger animals and produce a fruiting body that releases spores for reproduction.cite web |url=http://channel.nationalgeographic.com/channel/extraterrestrial/ |title=National Geographic Channel: EXTRATERRESTRIAL |accessdate=2008-01-05 |format= |work=]

See also

* Carnivorous fungus
* Carnivorous plant
* Protocarnivorous plant

References