{"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://reefs.com/#organization","name":"","url":"https://reefs.com/","sameAs":["https://www.facebook.com/reefscom","https://www.linkedin.com/company/reefs-com","http://www.youtube.com/c/Reefscom","https://www.pinterest.com/reefscom/","https://twitter.com/reefscom"]},{"@type":"WebSite","@id":"https://reefs.com/#website","url":"https://reefs.com/","name":"Reefs.com","publisher":{"@id":"https://reefs.com/#organization"},"potentialAction":{"@type":"SearchAction","target":"https://reefs.com/?s={search_term_string}","query-input":"required name=search_term_string"}},{"@type":"WebPage","@id":"https://reefs.com/2013/08/15/caviar-eating-hydroids/#webpage","url":"https://reefs.com/2013/08/15/caviar-eating-hydroids/","inLanguage":"en-US","name":"Caviar-Eating Hydroids\u2026 - Reefs.com","isPartOf":{"@id":"https://reefs.com/#website"},"image":{"@type":"ImageObject","@id":"https://reefs.com/2013/08/15/caviar-eating-hydroids/#primaryimage","url":"https://cdn.reefs.com/blog/wp-content/uploads/2013/08/reef-aquarium-2013-08-14-at-9.09.53-PM.png","width":200,"height":200},"primaryImageOfPage":{"@id":"https://reefs.com/2013/08/15/caviar-eating-hydroids/#primaryimage"},"datePublished":"2013-08-15T14:00:50+00:00","dateModified":"2016-11-03T01:18:44+00:00","description":"Caviar-Eating Hydroids\u2026 - Some Of The Weirdest Critters All right, I admit it.\u00a0 I am a fan of weird and bizarre animals.\u00a0 And, by definition, since nothing truly bizarre can have a backbone, that means I am fond of weird invertebrates.\u00a0 And by doggies, have I got one for you! And me! I have been working diligently on my next article for CORAL and it is coming along nicely.\u00a0 And, of course, that sounds a lot like \u201cSo far, so good!\u201d, a phrase heard 29 times, once as he passed each floor, by a fellow who jumped off a 30 story building.\u00a0 Actually, I do think it is going well.\u00a0 Nonetheless, I felt the need for a mental break yesterday and started to do some surfing looking for odd critters. And, boy, oh boy\u2026\u00a0 While doing a dance with Ms. Google, I came across a rather enigmatic headline, \u201cPolypodium hydriforme, (Coelenterata) in Paddlefish from the Upper Missouri River Drainage.\u201d Several things about this sentence started the chimes going at full volume for me.\u00a0 First, paddlefish are strange fish.\u00a0 Related to sturgeon, they look rather like sawfish, but unlike sawfish, they live in freshwater.\u00a0 Prior to when the Missouri River was turned into a series of interconnected lakes, paddlefish ranged in the Yellowstone River, probably up to Livingston, Montana, about 30 miles south of where I live.\u00a0 Now, paddlefish are vanishingly rare and becoming rarer by the hour.\u00a0 All species go extinct, but the time when the Missouri River populations of Paddlefish exit the stage appears to be approaching much more rapidly than might have been thought the case even a few decades ago.\u00a0 Which I think is really too bad, as I think they are neat fish.\u00a0 Second, the first three words of the sentence, \u201cPolypodium hydriforme (Coelenterata), really woke me up.\u00a0 Polypodium hydriforme is obviously a species name.\u00a0 But, I didn\u2019t have a clue about what it really was.\u00a0 No biggie, there.\u00a0 Most things in fresh water, even around here where I was sorta raised, are not species I am familiar with.\u00a0 However, the word \u201cCoelenterata\u201d in parentheses following the species name fired the pot to a rapid boil, as it means that P. hydriforme is in the Coelenterata. \u00a0Or at least the authors of the article thought so. \u00a0Well, no.\u00a0 Nothing is in the Coelenterata; the term is obsolete, at least it is in the English speaking zoological world.\u00a0 It was the name given for a supposed group consisting of the fusion of the Cnidaria and Ctenophora.\u00a0 Since those two groups are not related, at all, and since the fact that they are not related was determined before the turn of the 20th Century, the use of \u201cCoelenterata\u201d means that 1) the authors are clearly not invertebrate zoologists, and 2) they more than likely mean to use Cnidaria, as no ctenophore has ever lived in fresh water. Okay, so revising the sentence a bit, it would read, \u201cPolypodium hydriforme (Cnidaria) in Paddlefish\u2026\u00a0\u00a0 IN paddlefish.\u00a0 IN Paddlefish???\u00a0 Not: \u201cPolypodium hydriforme in the diet of Paddlefish\u201d, but \u201cPolypodium hydriforme in paddlefish\u201d. I leaned back in my chair and took a drink of coffee, hoping the caffeine soup would shake any cobwebs out.\u00a0 In Paddlefish\u2026\u00a0 It seemed to me the only thing that made sense would be that P. hydriforme is inside Paddlefish.\u00a0 Now, parasitic cnidarians are rare.\u00a0 That life style is not unheard of in the phylum, I know of a couple of examples of marine species that are parasites, but it is uncommon; one parasitic interaction involves a sea anemone whose larvae eat the gonads of a specific species of jellyfish is illustrated below. Larval sea anemone (Peachia quiquecapitata) eating the gonads from the radial canals of the jellyfish (Clytia gregaria). \u00a0The anemone larva has eaten two and one half of the four gonads. \u00a0Most authorities consider this interaction \u00a0parasitism, \u00a0others say it is predation. There is, however, one economically very important and decidedly strange, exceptionally odd and highly derived group of about 1200 species that was batted around from phylum to phylum for about a century before it ended up in the Cnidaria about 15 years ago.\u00a0 The organisms in this group, the Myxozoa, didn\u2019t really seem to belong anywhere. \u00a0A typical myxozoan genus was Myxobolus.\u00a0 As with many parasites, there are several different life history stages; however, the spore stage in Myxobolus was characterized by have a shell or \u201ctest\u201d consisting of several cells joined together with intercellular junctions, a characteristic of multicellular animals, not protists or protozoans.\u00a0 Inside the test was a syncytial mass, basically a mass of protoplasm with several nuclei, but no cell membranes, and\u2026 wait for it\u2026 two so-called \u201cpolar capsules.\u201d These polar capsules were secreted by the cells that contained them, and each consisted of a capsule with an involuted, spirally-coiled, thread that explosively extends to attach to the hosts\u2019 tissues.\u00a0 This sounds suspiciously like the description of a nematocyst.\u00a0 But, obviously it couldn\u2019t be a nematocyst, because only cnidarians had nematocysts, and these creatures were obviously not cnidarians.\u00a0 Or, put another way, they weren\u2019t cnidarians until the techniques became available and some researchers looked at their genetic materials, and compared it to the genetic material in Hydrozoans, and, \u201cKazango, Presto, Chango\u201d.\u00a0 They went from being Myxozoan protozoans to being highly modified Hydrozoans, in the phylum Cnidaria. \u00a0That had to be one of the most rapid evolutionary advances known, from a protozoan to a cnidarian, all in the time it took to publish some research findings! \u00a0In other words, the Myxozoa are actually some really funky tremendously highly modified hydroids.\u00a0 And, the polar capsules could actually be seen to be rather typical nematocysts known as atrichous isorhizas. Okay, so there are some strange cnidarians that are parasites that don\u2019t look at all like cnidarians.\u00a0 But, what about Polypodium? The species Polypodium hydriforme was described 1885 as parasite of sturgeons.\u00a0 This, by itself is unremarkable, and the parasite had been found in some other fish, it would likely be unnoticed or of little consequence.\u00a0 However, this parasite lives inside the oocytes, or developing eggs of sturgeon; Black Sea sturgeon.\u00a0 In other words, it eats caviar, before the sturgeon can deposit the caviar outside its body.\u00a0 Given that caviar is legendary for its value, any parasite that gets to it first has to be of some importance. Polypodium hydriforme is unusual in a number of regards.\u00a0 First, it lives within the cells of its host.\u00a0 That is not unusual for a protozoan or protistan parasite, such as malaria; however, it is almost unheard of for a animal parasite. \u00a0Normally animal parasites, for example, flukes, \u00a0live in the tissues or the blood of the host, not within the cells. \u00a0For most of its life span in the host, which may be several years, P. hydrifome individuals are essentially inside out, with the gastrodermis located as an outer layer presumably digesting host oocyte materials. Some parts of the life cycle of this organism are fairly well known, but there are some interesting gaps.\u00a0 How the animal gets into its host\u2019s eggs is not clearly known.\u00a0 However, once into the oocytes, \u201cPolypodium develops from a binucleate cell into an inside-out planuliform larva and then into an elongate inside-out stolon; the epidermal cell layer is located internal to the body and the gastrodermis is located externally.\u00a0 The embryo, larva and stolon are surrounded by a protective polyploid cell, which also functions in digestion.\u00a0 Just prior to host spawning, Polypodium everts to the normal position of cell layers, revealing tentacles scattered along the stolon. During eversion, the yolk of the\u00a0host oocyte fills the gastral cavities of the parasite, supplying the future free-living stage with nutrients. \u00a0Finally, upon emerging from the host egg in fresh water, the free living stolon (Figure 1A) fragments into individual medusoid-like forms (Figure 1B) that go on to multiply by means of longitudinal fission, form sexual organs, and ultimately infect host fish with their gametophores.\u201d\u00a0 Quoted from Evans, N. A. et al. 2008.\u00a0 Quotation and image use allowed under a Creative Commons Attribution License. Figure 1 from Evans, N. M. et al. 2008. Used by permission of Creative Commons Attribution License This animal is a hydrozoan or hydroid that spends a long portion of its life as an inside-out parasite living inside the oocytes or developing egg masses of sturgeon, or paddlefishes digesting the developing eggs.\u00a0 Then when its host spawns, the parasite turns itself inside out again, thus becoming a normally oriented hydrozoan, which apparently takes up an external lifestyle.\u00a0 At some time in the future, they develop gonads, spawn, and their larvae infect a new generation of fishes. I think this one is bizarre enough for me, today.\u00a0 I hope you enjoyed this tale of strangeness amongst the caviar-eating hydroid parasites. \u00a0References: Evans, N. M., A. Lindner, E. V. Raikova, A. G. Collins and P. Cartwright. 2008. \u00a0Phylogenetic placement of the enigmatic parasite, Polypodium hydriforme, within the Phylum Cnidaria. BMC Evolutionary Biology, 8:139 doi:10.1186/1471-2148-8-139 This article is available from: http://www.biomedcentral.com/1471-2148/8/139 \u00a9 2008 Evans et al; licensee BioMed Central Ltd.\u00a0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Holloway Jr. H. L., T. A. Dick, and C. A. Ottinger. 1991. Polypodium hydriforme, (Coelenterata) in Paddlefish from the Upper Missouri River Drainage. Journal of Aquatic Animal Health, 3: 210-212 Raikova, E. V. 1994. Life cycle, cytology, and morphology of Polypodium hydriforme, a coelenterate parasite of the eggs of Ascipeniform fishes.\u00a0 Journal of Parasitology. 80:1-22."},{"@type":"Article","@id":"https://reefs.com/2013/08/15/caviar-eating-hydroids/#article","isPartOf":{"@id":"https://reefs.com/2013/08/15/caviar-eating-hydroids/#webpage"},"author":{"@id":"https://reefs.com/author/Reef-To-Rainforest/#author","name":"Reef To Rainforest"},"publisher":{"@id":"https://reefs.com/#organization"},"headline":"Caviar-Eating Hydroids\u2026","datePublished":"2013-08-15T14:00:50+00:00","dateModified":"2016-11-03T01:18:44+00:00","commentCount":0,"mainEntityOfPage":"https://reefs.com/2013/08/15/caviar-eating-hydroids/#webpage","image":{"@id":"https://reefs.com/2013/08/15/caviar-eating-hydroids/#primaryimage"},"articleSection":"Fish,Invertebrates,Science"},{"@type":"Person","@id":"https://reefs.com/author/Reef-To-Rainforest/#author","name":"Reef To Rainforest","image":{"@type":"ImageObject","@id":"https://reefs.com/#personlogo","url":"https://cdn.reefs.com/blog/wp-content/uploads/2014/01/d721reef-to-rainforest.jpg","caption":"Reef To Rainforest"},"description":"REEF to RAINFOREST MEDIA is an independent, award-winning publishing house based in Shelburne, Vermont founded in 2009. Reef to Rainforest publishes high-acclaimed magazines, digital content, and books for aquarists and underwater naturalists. CORAL is the world\u2019s leading marine aquarium magazine, read in English in more than 100 countries. Available in high-quality print and digital editions. AMAZONAS is the world\u2019s leading freshwater-only aquarium magazine. Both titles are originally published in German by Matthias Schmidt and Natur und Tier -Verlag, Meunster, Germany, and are now available in English in high-quality print and digital editions produced by Reef to Rainforest Media.","sameAs":[]}]}

Caviar-Eating Hydroids…

Reef To RainforestBy Reef To Rainforest 6 years ago
Home  /  Fish  /  Caviar-Eating Hydroids…

 All right, I admit it.  I am a fan of weird and bizarre animals.  And, by definition, since nothing truly bizarre can have a backbone, that means I am fond of weird invertebrates.  And by doggies, have I got one for you! And me! I have been working diligently on my next article for CORAL and it is coming along nicely.  And, of course, that sounds a lot like “So far, so good!”, a phrase heard 29 times, once as he passed each floor, by a fellow who jumped off a 30 story building.  Actually, I do think it is going well.  Nonetheless, I felt the need for a mental break yesterday and started to do some surfing looking for odd critters. And, boy, oh boy…  While doing a dance with Ms. Google, I came across a rather enigmatic headline, “Polypodium hydriforme, (Coelenterata) in Paddlefish from the Upper Missouri River Drainage.” Several things about this sentence started the chimes going at full volume for me.  First, paddlefish are strange fish.  Related to sturgeon, they look rather like sawfish, but unlike sawfish, they live in freshwater.  Prior to when the Missouri River was turned into a series of interconnected lakes, paddlefish ranged in the Yellowstone River, probably up to Livingston, Montana, about 30 miles south of where I live.  Now, paddlefish are vanishingly rare and becoming rarer by the hour.  All species go extinct, but the time when the Missouri River populations of Paddlefish exit the stage appears to be approaching much more rapidly than might have been thought the case even a few decades ago.  Which I think is really too bad, as I think they are neat fish.  Second, the first three words of the sentence, “Polypodium hydriforme (Coelenterata), really woke me up. MORE: Caviar-Eating Hydroids…

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REEF to RAINFOREST MEDIA is an independent, award-winning publishing house based in Shelburne, Vermont founded in 2009. Reef to Rainforest publishes high-acclaimed magazines, digital content, and books for aquarists and underwater naturalists. CORAL is the world’s leading marine aquarium magazine, read in English in more than 100 countries. Available in high-quality print and digital editions. AMAZONAS is the world’s leading freshwater-only aquarium magazine. Both titles are originally published in German by Matthias Schmidt and Natur und Tier -Verlag, Meunster, Germany, and are now available in English in high-quality print and digital editions produced by Reef to Rainforest Media.

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