The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform
Daniel Sher - One of the best experts on this subject based on the ideXlab platform.
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The FASEB Journal • Research Communication
2013Co-Authors: Daniel Sher, Yelena Fishman, Naomi Melamed-book, Mingliang Zhang, Eliahu ZlotkinAbstract:Osmotically driven prey disintegration in the Gastrovascular Cavity of the green hydra by a pore-forming protei
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Many symbiotic algae are observed in the apical part of Chlorohydra viridissima endodermal digestive cells following feeding with Artemia.
2013Co-Authors: Yelena Fishman, Eliahu Zlotkin, Daniel SherAbstract:The symbiotic algae can be seen as small (∼10 µm) green spheres, and those found in the apical part of the cells are marked by arrowheads. A) Unfed Chlorohydra; B) Chlorohydra 15 minutes after feeding; C) Chlorohydra 5 hours after feeding. en = endoderm, ec = ectoderm, gvc = Gastrovascular Cavity, art = artemia. The dashed line between the endoderm and the mesoderm denotes the mesoglea. Bar = 50 µm. D) A quantitative analysis of the number of symbiotic algae in the apical third of the endoderm, at different times after feeding. Values and error bars represent averages and SE from 4–6 animals. There number of symbionts in the apical part of the cell was weakly affected by time (ANOVA, F = 5.067, p = 0.025) and time by treatment (F = 4.267, p = 0.04) but strongly affected by the treatment (F = 26.667, p
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Expulsion of symbiotic algae by apocrine secretion and exocytosis during feeding by Chlorohydra.
2013Co-Authors: Yelena Fishman, Eliahu Zlotkin, Daniel SherAbstract:en = endoderm, gvc = Gastrovascular Cavity. A) A general view of the apical part of Chlorohydra endoderm, 15 minutes after feeding. A large membrane-bound “aposome” is seen within the GVC, adjacent to the apical membrane of an endodermal digestive cell. (black arrowhead). A symbiotic alga is in the process of exocytosis from the aposome (enlarged in the inset), and several others are seen in the apical part of the endoderm (white arrowheads). Bar = 10 µm (1 µm in the inset). B) Expulsion of alga during apocrine secretion, 15 minutes after feeding. Note heterogenous aposomes within the GVC (black arrowheads), one of which contains an alga (algae are marked by white arrowheads). Bar = 10 µm. C) Enlargement of the aposome marked by an square in B. The aposome contains one intact alga (in the process of exocytosis, white arrowhead), as well as possibly another being digested (grey arrowhead). * = mitochondria. Bar = 5 µm. D) An aposome containing four symbiotic algae within the GVC (white arrowheads). Note the microvilli seen on the apical membrane of an endodermal cell (black arrowhead). Bar = 10 µm.
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The evolutionary origin of the Runx/CBFbeta transcription factors – Studies of the most basal metazoans-6
2011Co-Authors: James C Sullivan, Daniel Sher, Miriam Eisenstein, Katsuya Shigesada, Adam M Reitzel, Heather Marlow, Ditsa Levanon, Yoram Groner, John R Finnerty, Uri GatAbstract:Les and mouth region of adult anemones. No staining could be seen when a control probe from the sense strand was used (right animal). An inset from A, showing strong expression in the tentacle tips (arrow). Expression of in the mouth and extended upper pharynx of the same animal as depicted in A and B. Expression levels in the mouth region differed between different animals. General architecture of the tentacles and mouth region, showing the location of the enlarged micrographs in E and H (panel H is of a different serial section from the same anemone). Ten = tentacle, phx = pharynx. Scale bar = 100 μm. Expression of at the base of the ectoderm of the tentacles (arrowheads) en = endoderm, ec = ectoderm, mes-mesoglea. Bar in E = 100 μm, in F = 20 μm. Expression of in the ectoderm of the mouth (arrows). en = endoderm, ec = ectoderm, mes-mesoglea, gvc = Gastrovascular Cavity. Bar = 100 μm Enlargement of a region in the mouth, showing the CBFβ expression in cells close to large microbasic mastigophore nematocysts (arrowheads) Bar = 20 μm. Thin (2 μm) epoxy cross section through the mouth region stained with Methylene Blue, revealing the secretory gland cells (gc) and abundance of microbasic mastigophore nematocytes (mbm) of different sizes. Bar = 20 μm.Copyright information:Taken from "The evolutionary origin of the Runx/CBFbeta transcription factors – Studies of the most basal metazoans"http://www.biomedcentral.com/1471-2148/8/228BMC Evolutionary Biology 2008;8():228-228.Published online 5 Aug 2008PMCID:PMC2527000.
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A hydra with many heads: protein and polypeptide toxins from hydra and their biological roles.
Toxicon : official journal of the International Society on Toxinology, 2009Co-Authors: Daniel Sher, Eliahu ZlotkinAbstract:Hydra have been classical model organisms for over 250 years, yet little is known about the toxins they produce, and how they utilize these toxins to catch prey, protect themselves from predators and fulfill other biological roles necessary for survival. Unlike typical venomous organisms the hydra allomonal system is complex and "holistic", produced by various stinging cells (in the hunting tentacles and body ectoderm) as well as by non-nematocystic tissue. Toxic proteins also fulfill novel, non-allomonal roles in hydra. This review described the toxins produced by hydra within the context of their biology and natural history. Hydra nematocyst venom contains a high-molecular weight (>100 kDa) hemolytic and paralytic protein and a protein of approximately 30 kDa which induces a long-lasting flaccid paralysis. No low-molecular weight toxicity is observed, suggesting the lack of "classical" 4-7 kDa neurotoxins. The occurrence of a potent phospholipase activity in the venom is supported by the detection of several venom-like phospholipase A2 genes expressed by hydra. Hydra also produce toxins which are not part of the nematocyst venom. In the green hydra, Hydralysins, a novel family of Pore-Forming Proteins, are secreted into the Gastrovascular Cavity during feeding, probably helping in disintegration of the prey. Other putative non-nematocystic "toxins" may be involved in immunity, development or regulation of behavior. As the first venomous organism for which modern molecular tools are available, hydra provide a useful model to answer many outstanding questions on the way venomous organisms utilize their toxins to survive.
Michael Gudo - One of the best experts on this subject based on the ideXlab platform.
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Die Weichkörperkonstruktion vonCalceola sandalina (Rugosa, Anthozoa) — Konstruktionszusammenhänge, Ontogenese, Evolution und Funktionsweisen
Palaeontologische Zeitschrift, 2000Co-Authors: Michael GudoAbstract:The slipper-like corallum ofCalceola sandalina comprises the calyx and the lid. It was generated by an anthozoan-like coral. Anthozoan polyps have a barrel-like shape that is produced and maintained by the activity of internal tethering elements and muscular structures in the body wall. All these structures counteract the hydrodynamics of the Gastrovascular Cavity.
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Die Weichkörperkonstruktion vonCalceola sandalina (Rugosa, Anthozoa) — Konstruktionszusammenhänge, Ontogenese, Evolution und Funktionsweisen
Paläontologische Zeitschrift, 2000Co-Authors: Michael GudoAbstract:The slipper-like corallum of Calceola sandalina comprises the calyx and the lid. It was generated by an anthozoan-like coral. Anthozoan polyps have a barrel-like shape that is produced and maintained by the activity of internal tethering elements and muscular structures in the body wall. All these structures counteract the hydrodynamics of the Gastrovascular Cavity. In this reconstruction of the soft parts of Calceola the functional aspects pointed out by Richter (1929) will be reviewed and revised and partially corrected. Calceola was reconstructed on the basis of the model of rugose polyps. Consequently it consisted of single mesenteries which were added in four sectors in a serial manner. The lid was formed on the counter side and is explained as a bulge of the basal parts of the soft body. The lid was connected coherently by the mesenteries to the whole construction. It could be closed by contraction of the mesenteries and opened by regeneration of the hydraulic volume in the gastric Cavity. As a mechanical consequence of moving the lid a straight hinge was developed between the calyx and the lid. The soft body of Calceola developed by quite simple structural modifications of a rugose coral. The most important modification was the bulging of the basal parts of the soft body on the counter side which formed the lid. This bulge enlarged the surface for adhesion to the substrate and might have been an advantage in survival as well. The soft body generated its own substrate giving it the specific slipper shape. This shape prevented Calceola from sinking into soft or muddy substrate by the principle of a snowshoe which also enabled Calceola to conquer new territories. The lid meant protection where enemies and pollution were concerned. The slipper shape and the lid of Calceola indicated a complex evolutionary pathway, but they evolved by simple modifications of an ancestor with a round diameter. The slipper shape is just a mechanical consequence of the possession of a flappable lid. Das pantoffelförmige Kalkgerüst von Calceola sandalina , bestehend aus einem Kelch und einem Deckel, wurde von einem Anthozoenpolypen gebildet. Diese Polypen haben eine tonnen- oder zylinderartige Körperform, die durch das Wechselspiel interner Verspannungselemente (Mesenterien), einer muskulär verspannten Außenwand und der als Hydroskelett wirkenden Gastralraumfüllung bestimmt wird. Der Weichkörper von Calceola ist nicht erhalten und muß darum rekonstruiert werden. Hierbei werden Aspekte der funktioneilen Überlegungen von Richter (1929) zum Kalkgerüst und Weichkörper von Calceola in einen konstruktionsmorphologischen Begründungszusammenhang eingebunden, ergänzt und teilweise korrigiert. Der Polyp von Calceola hatte, wie alle rugosen Korallen, Einzelmesenterien, die während der Individual-Entwicklung in Quadranten hinzuwuchsen. Der Deckel entstand durch Auswulstung der basalen Körperabschnitte in Richtung der Gegenseite. Dort wurde Karbonat produziert, so daß eine Kalkplatte (der Deckel) entstand, auf dem sich wie im Kelch die Mesenterienzwischenräume als Kalksepten abbildeten. Der Deckel konnte durch Kontraktion der Mesenterien verschlossen und durch Regeneration der Gastralfüllung geöffnet werden. Hierbei entstand durch mechanische Nötigung automatisch eine gerade Kante als Scharniergelenk zwischen Deckel und Kelch und damit die typische Pantoffelform. Calceola entwickelte sich mit wenigen unspektakulären strukturellen Veränderungen aus einem Vorläufer ohne Deckel. Die wichtigste Veränderung war die Auswulstung der basalen Körperabschnitte auf der Gegenseite, von denen der Deckel gebildet wurde. Vorteil dieser Auswulstung ist eine größere Auflagefläche und damit verbunden auch die Adhäsionsfläche auf dem Substrat. Diese Form verhindert wie ein Schneeschuh das Einsinken in weiche oder schlammige Substrate, so daß entsprechende Lebensräume neu erschlossen werden konnten. Zusätzlich bot der Deckel Schutz vor Verschmutzung oder Freßfeinden. Der Deckel und die Pantoffelform von Calceola entstanden aus konstruktiven Zwängen heraus und zeugen von einer Auseinandersetzung des Organismus mit seinem Lebensraum.
Alina M. Szmant - One of the best experts on this subject based on the ideXlab platform.
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Responses of coral Gastrovascular Cavity pH during light and dark incubations to reduced seawater pH suggest species-specific responses to the effects of ocean acidification on calcification
Coral Reefs, 2020Co-Authors: Colleen B. Bove, Robert F. Whitehead, Alina M. SzmantAbstract:Coral polyps have a fluid-filled internal compartment, the Gastrovascular Cavity (GVC). Respiration and photosynthesis cause large daily excursions in GVC oxygen concentration (O2) and pH, but few studies have examined how this correlates with calcification rates. We hypothesized that GVC chemistry can mediate and ameliorate the effects of decreasing seawater pH (pHSW) on coral calcification. Microelectrodes were used to monitor O2 and pH within the GVC of Montastraea cavernosa and Duncanopsammia axifuga (pH only) in both the light and the dark, and three pHSW levels (8.2, 7.9, and 7.6). At pHSW 8.2, GVC O2 ranged from ca. 0 to over 400% saturation in the dark and light, respectively, with transitions from low to high (and vice versa) within minutes of turning the light on or off. For all three pHSW treatments and both species, pHGVC was always significantly above and below pHSW in the light and dark, respectively. For M. cavernosa in the light, pHGVC reached levels of pH 8.4–8.7 with no difference among pHSW treatments tested; in the dark, pHGVC dropped below pHSW and even below pH 7.0 in some trials at pHSW 7.6. For D. axifuga in both the light and the dark, pHGVC decreased linearly as pHSW decreased. Calcification rates were measured in the light concurrent with measurements of GVC O2 and pHGVC. For both species, calcification rates were similar at pHSW 8.2 and 7.9 but were significantly lower at pHSW 7.6. Thus, for both species, calcification was protected from seawater acidification by intrinsic coral physiology at pHSW 7.9 but not 7.6. Calcification was not correlated with pHGVC for M. cavernosa but was for D. axifuga. These results highlight the diverse responses of corals to changes in pHSW, their varying abilities to control pHGVC, and consequently their susceptibility to ocean acidification.
Eliahu Zlotkin - One of the best experts on this subject based on the ideXlab platform.
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The FASEB Journal • Research Communication
2013Co-Authors: Daniel Sher, Yelena Fishman, Naomi Melamed-book, Mingliang Zhang, Eliahu ZlotkinAbstract:Osmotically driven prey disintegration in the Gastrovascular Cavity of the green hydra by a pore-forming protei
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Many symbiotic algae are observed in the apical part of Chlorohydra viridissima endodermal digestive cells following feeding with Artemia.
2013Co-Authors: Yelena Fishman, Eliahu Zlotkin, Daniel SherAbstract:The symbiotic algae can be seen as small (∼10 µm) green spheres, and those found in the apical part of the cells are marked by arrowheads. A) Unfed Chlorohydra; B) Chlorohydra 15 minutes after feeding; C) Chlorohydra 5 hours after feeding. en = endoderm, ec = ectoderm, gvc = Gastrovascular Cavity, art = artemia. The dashed line between the endoderm and the mesoderm denotes the mesoglea. Bar = 50 µm. D) A quantitative analysis of the number of symbiotic algae in the apical third of the endoderm, at different times after feeding. Values and error bars represent averages and SE from 4–6 animals. There number of symbionts in the apical part of the cell was weakly affected by time (ANOVA, F = 5.067, p = 0.025) and time by treatment (F = 4.267, p = 0.04) but strongly affected by the treatment (F = 26.667, p
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Expulsion of symbiotic algae by apocrine secretion and exocytosis during feeding by Chlorohydra.
2013Co-Authors: Yelena Fishman, Eliahu Zlotkin, Daniel SherAbstract:en = endoderm, gvc = Gastrovascular Cavity. A) A general view of the apical part of Chlorohydra endoderm, 15 minutes after feeding. A large membrane-bound “aposome” is seen within the GVC, adjacent to the apical membrane of an endodermal digestive cell. (black arrowhead). A symbiotic alga is in the process of exocytosis from the aposome (enlarged in the inset), and several others are seen in the apical part of the endoderm (white arrowheads). Bar = 10 µm (1 µm in the inset). B) Expulsion of alga during apocrine secretion, 15 minutes after feeding. Note heterogenous aposomes within the GVC (black arrowheads), one of which contains an alga (algae are marked by white arrowheads). Bar = 10 µm. C) Enlargement of the aposome marked by an square in B. The aposome contains one intact alga (in the process of exocytosis, white arrowhead), as well as possibly another being digested (grey arrowhead). * = mitochondria. Bar = 5 µm. D) An aposome containing four symbiotic algae within the GVC (white arrowheads). Note the microvilli seen on the apical membrane of an endodermal cell (black arrowhead). Bar = 10 µm.
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A hydra with many heads: protein and polypeptide toxins from hydra and their biological roles.
Toxicon : official journal of the International Society on Toxinology, 2009Co-Authors: Daniel Sher, Eliahu ZlotkinAbstract:Hydra have been classical model organisms for over 250 years, yet little is known about the toxins they produce, and how they utilize these toxins to catch prey, protect themselves from predators and fulfill other biological roles necessary for survival. Unlike typical venomous organisms the hydra allomonal system is complex and "holistic", produced by various stinging cells (in the hunting tentacles and body ectoderm) as well as by non-nematocystic tissue. Toxic proteins also fulfill novel, non-allomonal roles in hydra. This review described the toxins produced by hydra within the context of their biology and natural history. Hydra nematocyst venom contains a high-molecular weight (>100 kDa) hemolytic and paralytic protein and a protein of approximately 30 kDa which induces a long-lasting flaccid paralysis. No low-molecular weight toxicity is observed, suggesting the lack of "classical" 4-7 kDa neurotoxins. The occurrence of a potent phospholipase activity in the venom is supported by the detection of several venom-like phospholipase A2 genes expressed by hydra. Hydra also produce toxins which are not part of the nematocyst venom. In the green hydra, Hydralysins, a novel family of Pore-Forming Proteins, are secreted into the Gastrovascular Cavity during feeding, probably helping in disintegration of the prey. Other putative non-nematocystic "toxins" may be involved in immunity, development or regulation of behavior. As the first venomous organism for which modern molecular tools are available, hydra provide a useful model to answer many outstanding questions on the way venomous organisms utilize their toxins to survive.
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Osmotically driven prey disintegration in the Gastrovascular Cavity of the green hydra by a pore-forming protein
FASEB journal : official publication of the Federation of American Societies for Experimental Biology, 2007Co-Authors: Daniel Sher, Yelena Fishman, Naomi Melamed-book, Mingliang Zhang, Eliahu ZlotkinAbstract:Pore-forming proteins (PFPs) are water-soluble proteins able to integrate into target membranes to form transmembrane pores. They are common determinants of bacterial pathogenicity and are often found in animal venoms. We recently isolated and characterized Hydralysins (Hlns), paralytic PFPs from the venomous green hydra Chlorohydra viridissima that are not found within the nematocytes, suggesting they are not involved in prey capture. The present study aimed to decipher the biological role of Hlns. Using in situ hybridization and immunohistochemistry, we show that Hlns are expressed by digestive cells surrounding the Gastrovascular Cavity (GVC) of Chlorohydra and secreted onto the prey during feeding. At biologically relevant concentrations, Hlns bind prey membranes and form pores, lysing the cells and disintegrating the prey tissue. Hlns are unable to bind Chlorohydra membranes, thus protecting the producing animal from the destructive effect of its own cytolytic protein. We suggest that osmotic disinte...
Yelena Fishman - One of the best experts on this subject based on the ideXlab platform.
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The FASEB Journal • Research Communication
2013Co-Authors: Daniel Sher, Yelena Fishman, Naomi Melamed-book, Mingliang Zhang, Eliahu ZlotkinAbstract:Osmotically driven prey disintegration in the Gastrovascular Cavity of the green hydra by a pore-forming protei
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Many symbiotic algae are observed in the apical part of Chlorohydra viridissima endodermal digestive cells following feeding with Artemia.
2013Co-Authors: Yelena Fishman, Eliahu Zlotkin, Daniel SherAbstract:The symbiotic algae can be seen as small (∼10 µm) green spheres, and those found in the apical part of the cells are marked by arrowheads. A) Unfed Chlorohydra; B) Chlorohydra 15 minutes after feeding; C) Chlorohydra 5 hours after feeding. en = endoderm, ec = ectoderm, gvc = Gastrovascular Cavity, art = artemia. The dashed line between the endoderm and the mesoderm denotes the mesoglea. Bar = 50 µm. D) A quantitative analysis of the number of symbiotic algae in the apical third of the endoderm, at different times after feeding. Values and error bars represent averages and SE from 4–6 animals. There number of symbionts in the apical part of the cell was weakly affected by time (ANOVA, F = 5.067, p = 0.025) and time by treatment (F = 4.267, p = 0.04) but strongly affected by the treatment (F = 26.667, p
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Expulsion of symbiotic algae by apocrine secretion and exocytosis during feeding by Chlorohydra.
2013Co-Authors: Yelena Fishman, Eliahu Zlotkin, Daniel SherAbstract:en = endoderm, gvc = Gastrovascular Cavity. A) A general view of the apical part of Chlorohydra endoderm, 15 minutes after feeding. A large membrane-bound “aposome” is seen within the GVC, adjacent to the apical membrane of an endodermal digestive cell. (black arrowhead). A symbiotic alga is in the process of exocytosis from the aposome (enlarged in the inset), and several others are seen in the apical part of the endoderm (white arrowheads). Bar = 10 µm (1 µm in the inset). B) Expulsion of alga during apocrine secretion, 15 minutes after feeding. Note heterogenous aposomes within the GVC (black arrowheads), one of which contains an alga (algae are marked by white arrowheads). Bar = 10 µm. C) Enlargement of the aposome marked by an square in B. The aposome contains one intact alga (in the process of exocytosis, white arrowhead), as well as possibly another being digested (grey arrowhead). * = mitochondria. Bar = 5 µm. D) An aposome containing four symbiotic algae within the GVC (white arrowheads). Note the microvilli seen on the apical membrane of an endodermal cell (black arrowhead). Bar = 10 µm.
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Osmotically driven prey disintegration in the Gastrovascular Cavity of the green hydra by a pore-forming protein
FASEB journal : official publication of the Federation of American Societies for Experimental Biology, 2007Co-Authors: Daniel Sher, Yelena Fishman, Naomi Melamed-book, Mingliang Zhang, Eliahu ZlotkinAbstract:Pore-forming proteins (PFPs) are water-soluble proteins able to integrate into target membranes to form transmembrane pores. They are common determinants of bacterial pathogenicity and are often found in animal venoms. We recently isolated and characterized Hydralysins (Hlns), paralytic PFPs from the venomous green hydra Chlorohydra viridissima that are not found within the nematocytes, suggesting they are not involved in prey capture. The present study aimed to decipher the biological role of Hlns. Using in situ hybridization and immunohistochemistry, we show that Hlns are expressed by digestive cells surrounding the Gastrovascular Cavity (GVC) of Chlorohydra and secreted onto the prey during feeding. At biologically relevant concentrations, Hlns bind prey membranes and form pores, lysing the cells and disintegrating the prey tissue. Hlns are unable to bind Chlorohydra membranes, thus protecting the producing animal from the destructive effect of its own cytolytic protein. We suggest that osmotic disinte...
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Hydralysin, a novel animal group-selective paralytic and cytolytic protein from a noncnidocystic origin in hydra
2003Co-Authors: Mingliang Zhang, Daniel Sher, Yelena Fishman, Eliahu ZlotkinAbstract:ABSTRACT: In Cnidaria, the production of neurotoxic polypeptides is attributed to the ectodermal stinging cells (cnidocytes), which are discharged for offensive (prey capture) and/or defensive purposes. In this study, a new paralysis-inducing (neurotoxic) protein from the green hydra Chlorohydra Viridissima was purified, cloned, and expressed. This paralytic protein is unique in that it (1) is derived from a noncnidocystic origin, (2) reveals a clear animal group-selective toxicity, (3) possesses an uncommon primary structure, remindful of pore-forming toxins, and (4) has a fast cytotoxic effect on insect cells but not on the tested mammalian cells. The possible biological role of such a noncnidocystic toxin is discussed. The Cnidaria (Coelenterata) comprise a worldwide phylum of aquatic radially symmetrical venomous predatory organ-isms (approximately 9000 species), representing one of the most primitive levels of multicellular organization. The Cnidaria are composed of two epithelial layers (ectoderm and endoderm), with a body plan consisting of a sac surrounding a Gastrovascular Cavity (coelenteron) with an oral opening, crowned by hunting tentacles
