Talk:Predatory dinoflagellate

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A fact from Predatory dinoflagellate appeared on Wikipedia's Main Page in the Did you know? column on 13 January 2008.

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This article was nominated for deletion on 8 March 2008. The result of the discussion was keep.

[edit] Problems

There are several rather large problems with this article. First of all, a parasite is not a carnivore, so the inclusion of parasites on this page is obviously questionable. Secondly, Ichthyophthirius multifiliis, Brooklynella hostilis, and Cryptocaryon irritansis are protozoans, not algae. Hence, ciliates are not algae. This all means that large parts of the content of this article do not even belong here. Ergo, this article is in serious need of gutting. --♦♦♦Vlmastra♦♦♦ (talk) 01:34, 13 January 2008 (UTC)

Very true. Another problem is that the term "Carnivorous alga"/"Carnivorous algae" is never used, looking at Google Scholar and PubMed. Narayanese (talk) 02:47, 13 January 2008 (UTC)

I noticed this too. 'Predatory' is often used (I believe) for microorganisms, but carnivorous is only used for plants and animals pretty much, and maybe a couple of predatory macroscopic fungi.--♦♦♦Vlmastra♦♦♦ (talk) 04:31, 13 January 2008 (UTC)

I saw this article on the main page and looked at it because "carnivore" and "algae" seemed to me a borderline oxymoron. I was disappointed to find it wasn't actually true algae but just protists. Was this article simply recklessly written?--Jpwrunyan (talk) 03:19, 13 January 2008 (UTC)

It seems so. One sees hair-brained bioterminology (to make one up myself) in bioliterature (another), but carnivorous algae seems comic bookish. --♦♦♦Vlmastra♦♦♦ (talk) 04:31, 13 January 2008 (UTC)

Gee, thanks for the feedback. Carnivorous algae was a requested article back in March (see [1] under Biology). I looked for sources for the term and found several, e.g. [2], [3], [4], [5]. Based on those, I redirected the term to Pfiesteria and then dinoflagellate as that seemed to be more general. After collecting articles over the past ten months on what my best guess was what the original page request might have asked for, I finally decided the pile was tall enough and "recklessly" started an article with the references I had. Granted, the term "carnivorous algae" seems to be more popular in the media and not so much in scholarly literature where "carnivorous dinoflagellate" or "predatory dinoflagellate" seems preferred to describe Pfiesteria and related species. Feel free to suggest a move or split. As for "parasites are not carnivores" - I found several hits on Google Books and Google Scholar for the term "carnivorous parasite" which should then be an oxymoron, but yet it appears in scholarly literature. - tameeria (talk) 05:18, 13 January 2008 (UTC)

Ah, the lead does say "in the media" when I look carefully. Still, what are ciliates doing here? Narayanese (talk) 11:52, 13 January 2008 (UTC)

I included ciliates mostly by analogy to dinoflagellates and because species of both phyla may be referred to as algae in the media. Both are alveolata and contain species that that are mixotrophic or autotrophic (phototrophic) and contain chloroplasts for photosynthesis. The term "algae" is not very well defined. E.g. the American Heritage Dictionary defines algae as "various chiefly aquatic, eukaryotic, photosynthetic organisms, ranging in size from single-celled forms to the giant kelp." Looking closely at the literature, the dinoflagellates mentioned in the article (Pfiesteria and related species, freshwater Oodinium) can take the form of a heterotrophic "carnivorous" stage or a phototrophic "algal" stage depending on feeding conditions. Thus calling them "algae" seems appropriate. I'm not sure if the same applies to the ciliate species mentioned, so maybe "carnivorous protist" might be a less confusing title. However, there are examples for photosynthetic ciliates. This study found that typically 30-40% of the ciliates in the water contained plastids and this study found that about 34% of ciliates contained chloroplasts. The photosynthetic ciliates (aka "phytociliates"), e.g. Mesodinium rubrum (e.g. [6]) and Laboea strobila (e.g. [7]) and others, are often lumped in with the phytoplankton and included in reports of "algal blooms" or red tides (e.g. see [8], [9], [10], [11], [12]). - tameeria (talk) 16:27, 13 January 2008 (UTC)

Several problems:

• The algae are of course paraphyletic and polyphyletic. Therefore arguing that the Alveolata must all be algae simply because some of them are is fallacious. Would you call Plasmodium an alga? The dinoflagellates are considered algae by all reputable sources, but most ciliates are not. I should add that many ciliates merely acquire chloroplasts temporarily from their prey for 2-3 weeks, or harbor symbiotic algae.

Comment: "Alga" is a completely non-taxonomic term. I'm not arguing that all alveolata are algae, I'm arguing that some that some have been referred to as algae in the media (and provided several references for that). Dinoflagellates are double-classified as both algae and protozoa and have actually more in common with protozoa based on molecular data from DNA sequences. The dinoflagellates that the news media called "carnivorous algae" also acquire chloroplasts from their algal prey, just as ciliates. - tameeria (talk) 04:09, 22 January 2008 (UTC)

Response: I am well aware that the algae are a catch-all group, but the protozoa are also quite polyphyletic. The dinoflagellates are distant from other algae, but they definitely meet the requirements of algae. Again, I have no problem with the inclusion of the dinoflagellates, but I believe that you included some organisms that do not contain chloroplasts.--♦♦♦Vlmastra♦♦♦ (talk) 01:40, 23 January 2008 (UTC)

• I would not recommend using a dictionary for scientific definitions, since they are more often unsatisfactory than not. A college level biology textbook would be preferable.

Textbook 1:

... we can divide protists into three categories: photosynthetic (plant-like) protists, or algae (singular, alga); ingestive (animal-like) protists, or protozoans; and absorptive (fungus-like) protists[...] Bear in mind, however, that although the terms alga and protozoa are useful in discussing protist ecology, they do not refer to monophyletic groups.

(Campbell, Reece: Biology, 7th edition)

Textbook 2:

Protists are often classified according to ecological roles into three major groups: algae, protozoa, and fungus-like protists. The term algae (Latin for "seaweeds") applies to about 10 phyla of protists that include both photosynthetic and nonphotosynthetic species (see Table 28.1). (Comment: Sadly, it is not clear from that table which 10 of the listed phyla are considered algae.) Photosynthetic algae produce organic compounds and oxygen, thereby providing substances used by heterotrophic organisms. ... Despite the common feature of photosynthesis, algae do not form a monophyletic group descended from a single common ancestor[...] These examples illustrate that the terms algae, protozoa, and fungus-like protists, while useful in describing ecological roles, lack taxonomic or evolutionary meaning.

(Brooker et al.: Biology, 1st edition)

Textbook 3:

Glossary in Starr & Taggart: Biology: The unity and diversity of life, 10th edition:

Alga, plural algae - Photosynthetic protistans, mainly; mostly are members of phytoplankton.

Textbook 4:

Glossary in Raven et al.: Biology, 8th edition:

Alga, pl. algae - A unicellular or simple multicellular photosynthetic organism lacking multicellular sex organs.

Response: Yes, yes, yes, I am very familiar with these definitions of algae, having used a practically identical one to overhaul the first half of the Algae article about a month ago. But you are preaching to the choir: what are you trying to prove? (Unless you want to put one of these definitions in the article, which would be great.--♦♦♦Vlmastra♦♦♦ (talk) 02:08, 23 January 2008 (UTC)

If you knew this so well, what was the point of your comment above ("I would not recommend using a dictionary for scientific definitions, since they are more often unsatisfactory than not. A college level biology textbook would be preferable.") other than wasting my time pointlessly digging up textbook examples? - tameeria (talk) 20:17, 23 January 2008 (UTC)

• I by far prefer to call these heterotrophic algae predatory rather than carnivorous, since they do not devour and digest their food internally, but rather digest and absorb externally.

Comment: Personal preference is not a good argument for changing anything on Wikipedia. I provided several references for the exact term "carnivorous algae" being used in the media. Plus, that was also the title of the requested article. Carnivorous simply means flesh-eating:

(Brooker et al.: Biology, 1st edition), Glossary:

Carnivore - an animal that consumes animal flesh or fluids.

Glossary in Starr & Taggart: Biology: The unity and diversity of life, 10th edition:

Carnivore - Animal that consumes mostly flesh.

Of course, if we assume that all carnivores are animals, there shouldn't be such as thing as carnivorous plants or carnivorous fungi either. - tameeria (talk) 04:09, 22 January 2008 (UTC)

Excuse me, that was badly worded. I meant that "predatory" may be more descriptive of the actual nature of these organisms; the other "Carnivorous algae" seems to be typical media hype. In any case, "predatory" seems to be the more common descriptor. Some carnivorous plants do devour their food in a rather animal-like fashion, thus the "nickname." As for "carnivorous fungi," "predatory" is somewhat more common, but both are seen, perhaps as an analogy to the carnivorous plants, but the literature searches provide better evidence for "predatory" as applied to the algae.--♦♦♦Vlmastra♦♦♦ (talk) 01:40, 23 January 2008 (UTC)

• Most of the sources you have used (in the article) are not scientific, but seem to be media reports and nonspecialist literature. I think that only scientific literature should be used on a scientific subject, unless specifically citing coverage in the media (which is very prone to inaccuracy and exaggeration).--♦♦♦Vlmastra♦♦♦ (talk) 19:03, 13 January 2008 (UTC)

Comment: Your thought on this stands against a specific request for an article to be added to Wikipedia. The article was requested on 2 June 2006 (diff). It stayed on the requested article list until 2 April 2007 (diff). It was probably taken off because it was no longer a red-link since I had created a redirect for it when I first stumbled over it. I always assumed that Wikipedia was about making it useful to the average user. If a user requests an article to be created for "carnivorous algae" I don't think a redirect is sufficient to fulfill that request. Instead of redirecting, the article should be rewritten to match the request more accurately, if that's a problem. - tameeria (talk) 04:09, 22 January 2008 (UTC)

Follow-up: When I searched Google Scholar, using quotation marks to make sure it only returned results where the terms appeared together, I got no results for the search term "carnivorous dinoflagellate"[13] and four pages of results for "predatory dinoflagellate".[14] Searching for "carnivorous algae" yeilded two results, one outdated and in the other carnivorous and algae were separated by a semicolon and thus not considered one term.[15] Unfortunately, my move to predatory alga seemed to have been in error[16][17], so I fixed the problem by calling this article Predatory dinoflagellate, which I have previously established to be common in the literature.

Comment: If the term is not used in scholarly literature, but the media uses the term, then an article can very well be based on citing the media. It just needs to be clear that this is how the media uses it, but it has no scientific usage. The current statement "the media has sometimes used the term carnivorous algae, but this appears uncommon in scientific literature" is just about as weasely as they come ("sometimes", "appears"). Part of the article (carnivorous algae in fiction) make no sense with the new title. - tameeria (talk) 04:09, 22 January 2008 (UTC)

Well, that really belongs on the talk page, but I have supported it (just on the talk page, not in the article). It is OR as it stands, so I will remove it. I do think that the scientific usage (or lack thereof) should somehow be mentioned in contrast with the media usage. --♦♦♦Vlmastra♦♦♦ (talk) 01:49, 23 January 2008 (UTC)

Finally, the last paragraph appears to be a list of appearances of the term in popular culture. These sorts of lists are discouraged, so I am marking it.--♦♦♦Vlmastra♦♦♦ (talk) 19:34, 13 January 2008 (UTC)

Comment: I would think if popular culture is where the term is used, then that should be legitimate part of the article. - tameeria (talk) 04:09, 22 January 2008 (UTC)

Not as a list of random trivia. See Wikipedia:Trivia sections and below. It should be merged with the rest of the article. --♦♦♦Vlmastra♦♦♦ (talk) 01:40, 23 January 2008 (UTC)

I have trimmed the material to include only distinctly predatory (in the strict sense of capturing/disabling/killing "prey") and marked the Pop Culture section. --♦♦♦Vlmastra♦♦♦ (talk) 22:45, 13 January 2008 (UTC)

Thanks for all the time spent discussing this. Looking back, I have to admit that "carnivorous algae" had a more sensational feel to it but I learned a lot from reading the discussion.--Jpwrunyan (talk) 02:53, 11 May 2008 (UTC)

[edit] Extra

Not all parasitic algae are carnivorous; some grow on plants instead of animals.^[1]

Parasitic algae are an economically important issue where fish are reared commercially or kept in aquaria at a high density and result in high mortality in affected fish populations. A study on ornamental fish from export farms in Sri Lanka found that on average 18.4% of all fish were infected with parasitic algae.^[2] Ciliates such as Ichthyophthirius multifiliis invade the gills and form trophonts visible as white spots feeding on their victim's skin (Ichthyophthiriasis or white spot disease). Other ciliates causing invasive infections in freshwater fish include for example Chilodonella, Hemiophrys, Ophryoglena, and Tetrahymena species.^[3] In marine fish, the disease is caused by Cryptocaryon. Clownfish disease or Brooklynellosis is caused by another marine ciliate, Brooklynella hostilis. Dinoflagellates such as Piscinoodinium cause gold dust disease in fish.

This material will be included in a future article on parasitic algae, or perhaps the Algae article itself.--♦♦♦Vlmastra♦♦♦ (talk) 20:05, 13 January 2008 (UTC)

I disagree with the whole carnivorous versus predatory versus parasitic "problem." A carnivore is simply a flesh-eating creature. A predator kills its prey. A parasite lives on its host without killing it. Both predators and parasites can be carnivores. If these statements (which I am basing on biology textbooks as well as scholarly literature) are considered wrong, I would like to see references saying that they are wrong. It appears I'm the only one who actually provided any references to the discussion on this page so far. - tameeria (talk) 05:27, 22 January 2008 (UTC)

So shall we consider all parasitic organisms carnivorous? Are pathogenic bacteria carnivorous? Or yeasts like Candida? Or even dodder or mistletoe? --♦♦♦Vlmastra♦♦♦ (talk) 02:02, 23 January 2008 (UTC)

That is twisting my words around for the sake of rhetoric. All I'm saying is that some parasites are carnivorous. Of course that does not apply to all parasites. Some dogs are poodles, but that does not mean all dogs are poodles. Here's an excerpt from scholarly literature: "Of 15 carnivorous parasitic insect clades..., six were more diverse than their predaceous or saprophagous sister groups,..." (Wiegmann et al., "Diversification of carnivorous parasitic insects," Am. Nat. 1993, Vol. 142, pp. 737-754) If carnivorous insects can be classified into carnivorous parasites (feeding off living hosts), carnivorous predators (killing their prey) and carnivorous saprophages (eating dead animals), I would assume the same might apply to other groups of flesh-eating organisms as well. Your point of "a parasite is not a carnivore" does not apply to all parasites and can be refuted with examples from scholarly literature. I have yet to see you come up with a reference to support your opinion on this. - tameeria (talk) 20:11, 23 January 2008 (UTC)

Can you please clarify your intentions for the deleted section? As far as I can tell, you deleted it because "ciliates are not algae" and then you say above that the deleted section is going to be included either in the algae article or one on parasitic algae. That is directly contradictory to the reason you gave for removing it in the first place. I don't see it anywhere and I have a feeling if I go ahead and use it to create an article on parasitic algae, it will just prompt a repeat of the "ciliates are no algae" discussion. - tameeria (talk) 14:15, 6 March 2008 (UTC)

I must have missed that. No, of course the material does not belong in an algal article. How about Ciliate? --♦♦♦Vlmastra♦♦♦ (talk) 14:25, 7 March 2008 (UTC)

[edit] Requested move