nematocysts in cnidariansnematocysts in cnidarians

Proc Natl Acad Sci USA. As this process continues, the channel between the digestive gland and the cnidosac opens and closes with the contractions of the gut (Fig. 1990;179:24353. In particular, a large family of unusual minicollagens has been demonstrated to form the highly resistant scaffold of the capsule. Urban & Fischer; 2018;97:28999. This type of sequestration contrasts with many others, which usually involve the internalization of whole cells [3] or of small chemicals that do not require internalization via phagocytosis [17,18,19]. J World Aquac Soc. JAG and DCL conceived of the study; JAG and VB collected data; JAG performed data analyses; all authors contributed to study design, andparticipated in data interpretation. The morphology of the adult cnidosac in Berghia stephanieae (Fig. 1E), supporting the longtime assertion that nematocysts (the organelles) are sequestered, rather full and intact nematocytes (the cells). Nematocysts or cnidocysts represent the common feature of all cnidarians. We initially staged juveniles based on previous descriptions of juvenile development [41], and selected animals between the early juvenile and juvenile stages, as these are the stages where the animals begin feeding and cerata emerge. All authors read and approved the final manuscript. J Mar Biol Assoc. In TEM images, we noted that sequestered nematocysts are separately bound in individual vacuoles (Fig. 2008 Feb 29;376(4):1008-20. doi: 10.1016/j.jmb.2007.10.090. Carr D, Carr C. On triggering and control of cnidocyst discharge. Nature of the metamorphic signal and its internal transduction in Larvae of the Nudibranch Phestilla Sibogae. Kristof A, Klussmann-Kolb A. Neuromuscular development of Aeolidiella stephanieae Valdz, 2005 (Mollusca, Gastropoda, Nudibranchia). Pink, orange, red, and brown cnidarians are commonly pigmented by carotenoids derived from crustaceans in their diet. Martin R, He M, Schrdl M, Tomaschko K-H. Cnidosac morphology in dendronotacean and aeolidacean nudibranch molluscs: from expulsion of nematocysts to use in defense? (Mollusca: Opisthobranchia) with a Description of the Kleptocnidae sequestered from its sea anemone prey. Cnidarian - Locomotion, feeding & symbioses | Britannica Carroll DJ, Kempf SC. Predators of cnidarians include Chordata (specifically fish, reptiles, and birds), Chaetognatha, Arthropoda, Ctenophora, Acoelomorpha, Platyhelminthes, and . Plant Physiol. Berghia stephanieae juveniles begin to feed on Exaiptasiadiaphana by seemingly attaching the anterior surface of the inner lip to their prey (Additional file 2: Video 1). A cnidocyte (also known as a cnidoblast or nematocyte) is an explosive cell containing one large secretory organelle called a cnidocyst (also known as a cnida (PLcnidae) or nematocyst) that can deliver a sting to other organisms. Marin A. These inconsistencies may be due to differences among species [46], differences between regeneration and development [45, 46], or lower resolution imaging techniques [41, 45, 46]. ). Prior to discharge the coiled cnidae tubule exists inside the cell in an "inside out" condition. We performed deconvolution of the datasets with the Leica Lightning deconvolution software, and visualized images using Fiji (version 2.3.0, [61]), and prepared image plates using the FigureJ plugin [62]. 1A), which is connected to the digestive gland via a short channel (Additional file 1: Figure S1). They all have tentacles with stinging cells called nematocysts that they use to capture food. This knowledge gap is mainly due to a lack of genetically tractable model systems among predators and their cnidarian prey. Accessibility 7) can enter the cnidosac during digestion, without first being internalized within digestive cells. J Linn Soc London, Zool. Martin R, Walther P. Effects of discharging nematocysts when an eolid nudibranch feeds on a hydroid. We embedded samples with Spurr's Low Viscosity Embedding Media Kit (Electron Microscopy Sciences #14,300), following the standard Firm formulation provided by the manufacturer, and cured at 60C overnight. nematocyst, minute, elongated, or spherical capsule produced exclusively by members of the phylum Cnidaria (e.g., jellyfish, corals, sea anemones). Introduction Cnidarian nematocysts are complex subcellular weapons with highly specialized forms and functions 1, 2. 2012;76:22961. Schindelin J, Arganda-Carreras I, Frise E, Kaynig V, Longair M, Pietzsch T, et al. FOIA Bethesda, MD 20894, Web Policies 2005;119:16776. Article This article was most recently revised and updated by, https://www.britannica.com/science/nematocyst. Stachowicz JJ, Lindquist N. Hydroid defenses against predators: the importance of secondary metabolites versus nematocysts. MeSH Article Nematocysts - The Stinging Cells | Zoology for IAS, IFoS and other Poly--glutamate synthesis during formation of nematocyst capsules in Hydra. 2009;156:2618. The threads of some nematocysts ensnare small prey by wrapping about them. B. stephanieae animals were fed Exaiptasia diaphana three days per week (Monday, Wednesday, Friday). Garg N, tibler UK, Eismann B, Mercker M, Bergheim BG, Linn A, Tuchscherer P, Engel U, Redl S, Marciniak-Czochra A, Holstein TW, Hess MW, zbek S. iScience. Minicollagen genes are one of the major structural components of the capsule. Nematocysts are the taxon-defining features of all cnidarians including jellyfish, sea anemones, and corals. Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA, 92037, USA, Jessica A. Goodheart,Vanessa Barone&Deirdre C. Lyons, You can also search for this author in Mariscal RN, Conklin EJ, Bigger CH. The long history of research on Hydra as a model organism has been accompanied by the cellular, mechanistic and morphological analysis of its nematocyst repertoire. A cnidocyte fires a structure that contains a toxin within the cnidocyst; this is responsible for the stings delivered by a cnidarian. 6. A nematocyst is a subcellular structure or organelle containing extrusive filaments found in two families of athecate dinoflagellates (a group of unicellular eukaryotes ), the Warnowiaceae and Polykrikaceae. van Oppen MJH, Oliver JK, Putnam HM, Gates RD. Chemoecology. 2003;143:53341. Privacy These images show development of the cnidosac and beginning of nematocyst sequestration: A pre-feeding juvenile, B juvenile with cnidosacs and small cerata buds, and C juvenile with two rows of cerata. That force is to be calculated as the mass of the mechanism's stylet multiplied by its acceleration. An official website of the United States government. Furthermore, both nematocysts and dinoflagellates can move into the cnidosac (Figs. Subsequent vesicle fusion enables the formation of a tubule outside of the capsule, which then invaginates into the capsule. Introduction. 2014;281:20133112. The https:// ensures that you are connecting to the Abbreviations: cs, cnidosac; en, entrance; dg, digestive gland, Dinoflagellate movement in a Berghia stephanieae juvenile. Springer; 2010;7:5. However, we know little about how these specialized phagocytic cells identify and select for nematocysts. All Cnidaria are aquatic, mostly marine, organisms. Feeding behavior, ceras structure, and nematocyst storage in the Aeolid Nudibranch, Spurilla Neapolitana (Mollusca). This causes a large concentration gradient of calcium across the cnidocyte plasma membrane. Movement and storage of nematocysts across development in the 5. 6, 7), we now know to focus on cnidophages when investigating the molecular mechanisms of nematocyst sequestration (Fig. The dynamically evolving nematocyst content of an anthozoan, a scyphozoan, and a hydrozoan. [12] Minicollagen genes form compact gene clusters in Cnidarian genomes, suggesting a diversification through gene duplication and subfunctionalization. https://doi.org/10.1186/s12983-022-00460-1, DOI: https://doi.org/10.1186/s12983-022-00460-1. Cnidocyte - Wikipedia government site. Part of Proc Biol Sci. 3BB), indicating that, if not fully mature, these cnidosac structures are at least fully functional. Abbreviations: bm, buccal mass; cs, cnidosac, d, dinoflagellates, dg, digestive gland; j, jaws; nc, nematocyte(s); nem, nematocyst(s); rad, radula; sp, spirocyst(s); spc, spirocyte(s). By using this website, you agree to our Basic Anatomy This anemone has tentacles and exhibits radial symmetry. 8600 Rockville Pike Pseudocnidae of ribbon worms (Nemertea): ultrastructure, maturation, and functional morphology. They are the largest (16 microns in diameter) and most complex nematocysts. They then placed the samples in dry acetone for 15min at room temperature (RT), followed by 50:50 (ethanol:Durcupan) for 1h or longer at RT and 100% Durcupan overnight. 7. Int J Dev Biol. The lack of a pore in this species is consistent with the description provided by Goodheart et al. 4CC, and DD) also begin adding further rows of cerata (usually symmetrically) at the posterior end of the animal as the juvenile grows longer. This organelle consists of a bulb-shaped capsule containing a coiled hollow tubule structure attached to it. This extension will become the cerata as the juveniles mature. Chemical or nematocyst-based defence in the nudibranch Cratena peregrina? Ozbek S, Balasubramanian PG, Holstein TW. Post-metamorphosis, Berghia stephanieae juveniles have elongate, translucent bodies with visible eyespots, statocysts, and ganglia, as well as large anterior cilia (Fig. [25]. 4AA). Non-muscle myosin II drives critical steps of nematocyst morphogenesis. 2023 Feb 28;26(3):106291. doi: 10.1016/j.isci.2023.106291. The lack of this structure in B. stephanieae suggests that this is not a necessary feature for managing such nematocysts. Your privacy choices/Manage cookies we use in the preference centre. Little is known about how common cellular mechanisms, like phagocytosis, can be modified to selectively internalize and store foreign structures. 2009 Dec 15;54(8):1038-45. doi: 10.1016/j.toxicon.2009.03.006. This prevents the cnidarian from stinging itself although sloughed off cnidae can be induced to fire independently. Studies on Cnidophage, Specialized Cell for Kleptocnida, of Pteraeolidia semperi (Mollusca: Gastropoda: Nudibranchia) [PhD]. Finally, the radula is pulled back in toward the jaws, bringing some of the E.diaphana tissue through the oral tube and pharynx and into the buccal cavity. The musculature surrounding the cnidosac becomes slightly thicker as the animals reach later stages (>2 rows of cerata) (Fig. We captured images on a JEOL 1400 plus TEM at 80kV with Gatan 4kx4k camera at the facility. Certain types of sea slugs, such as the nudibranch aeolids, are known to undergo kleptocnidy (in addition to kleptoplasty), whereby the organisms store nematocysts of digested prey at the tips of their cerata. Box indicates the tip of the ceras, where the cnidosac is found. Wgele H, Willan RC. nematocyst: a capsule, in certain cnidarians, containing a barbed, threadlike tube that delivers a paralyzing sting; Class Scyphozoa Class Scyphozoa, an exclusively marine class of animals with about 200 known species, includes all the jellies. However, selectivity for particular symbionts is more flexible than originally thought [9] and relies on the specificity of both the symbiont and host [10]. Exaiptasia diaphana from the great barrier reef: a valuable resource for coral symbiosis research. Clipboard, Search History, and several other advanced features are temporarily unavailable. Nematocysts are a type of cnidae, and it is the presence of cnidae that separates jellyfish and other cnidarians from other animals. As the animal continues to eat, the contractions of the gut move food particles into and out of the diverticula, until the digestive gland is completely full, or feeding is disrupted, or there is no more food to eat. 8B). Observational studies typically used a tentacle solution assay with a chemical stimulant to create discharge and cameras to record them. The architecture and operating mechanism of a cnidarian stinging Nat Methods. Jesus B, Jauffrais T, Trampe ECL, Goessling JW, Lekieffre C, Meibom A, et al. Although cnidarian nematocysts can serve as defensive structures, a diverse array of cnidarians are preyed on by species from a range of animal phyla (von Salvini-Plawen 1972; Arai 2005). Oecologia. 2002 Oct 29;99(22):14224-9 National Library of Medicine PubMed Central Cnidarians are recognizable by their radial symmetry and bodies made of two layers of living tissue with a gelatinous layer in-between. When touched, the cells are known to fire coiled threads that can either penetrate the flesh of the prey or predators of cnidarians, or ensnare it. Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. 3B). 2005;147:131321. Togawa Y. PubMed These early stage cnidosacs, prior to ceras formation, already have a clear musculature (Fig. 1976;54958. 2009;156:75361. B. stephanieae feeds on the cnidarian Exaiptasia diaphana, an anemone used to investigate cnidarian-dinoflagellate endosymbiosis [28], and is known to sequester nematocysts from E. diaphana [25, 29]. This finding is inconsistent with previous studies that place the formation of the cnidosac after cerata emerge. Cnidarians only have two body layers, the ectoderm and endoderm, separated by a jelly-like layer called the mesoglea. -, J Biol Chem. Seabra S, Zenleser T, Grosbusch AL, Hobmayer B, Lengerer B. Biomimetics (Basel). May 10, 2021 21.1: Features of the Animal Kingdom 21.3: Flatworms, Nematodes, and Arthropods OpenStax OpenStax The kingdom of animals is informally divided into invertebrate animals, those without a backbone, and vertebrate animals, those with a backbone. All sponges are aquatic and the majority of species are marine. San DiegoElectron Microscopy Core Facility for Transmission Electron Microscopy services and training. 1C, D; Additional file 1: Figures S2 and S3), we have evidence of the sequestration of nematocysts from multiple E.diaphana tissues(including the acontia and tentacles). 6) and dinoflagellates (Fig. By contrast, the two penetrant types of cnidocytes present in this species display a much broader localization, on the outer epithelial layer of the tentacles and body column, as well as on the pharynx epithelium and within mesenteries. Cnidae are among the most complex intracellular secretion products known. Phylum Cnidaria | Boundless Biology | | Course Hero sharing sensitive information, make sure youre on a federal 2007;7:65160. sharing sensitive information, make sure youre on a federal Cnidocyst structure and the biomechanics of discharge. However, the muscle layer is still not as thick as that of the cnidosacs in adult B. stephanieae (Fig. Like other nudibranchs, B. stephanieae sequesters nematocysts in a structure called the cnidosac that is found at the tips of finger-like dorsal projections called cerata [25]. 2015 Mar;32(3):740-53. doi: 10.1093/molbev/msu335. Greenwood PG. 2000;124:2808. Our results pave the way for future studies using live imaging and targeted gene editing to identify the molecular mechanisms involved in nematocyst sequestration. Furthermore, nematocysts are also clearly bound inside what appear to be cnidophages (Fig. This is accompanied by the release of a toxin cocktail stored in the capsule matrix. 2011 Oct;248(4):635-40. doi: 10.1007/s00709-010-0219-4. Histological slides and vouchers are available from the Scripps Institution of Oceanography Benthic Invertebrate Collection (SIO-BIC) for both Berghia stephanieae (slides, M18637-M18646; vouchers, M18660-M18661) and Exaiptasia diaphana (Co3615-Co3617). We performed imaging with a Leica Sp8 inverted confocal microscope equipped with a 20X objective (0.70 DRY) and a resonant scanner. Cnidae are used to capture prey and as a defense against predators. 8A), and only nematocysts (the organelles) are targeted and phagocytosed by cnidophages (Fig. Berghia stephanieae juvenile digestion. Careers. 2016;14:1724. B. stephanieae tissues (longitudinal section) include (D) the cnidosac (SIO-CIC M18637) and (F) digestive gland (SIO-BIC M18638). In Hydrozoans, in order to regulate discharge, cnidocytes are connected as "batteries", containing several types of cnidocytes connected to supporting cells and neurons. A cnidocyte (also known as a cnidoblast or nematocyte) is an explosive cell containing one large secretory organelle called a cnidocyst (also known as a cnida ( PL cnidae) or nematocyst) that can deliver a sting to other organisms. Invertebr Biol. During the discharge of nematocysts following a chemical or mechanical stimulus, the thread is expelled from within the capsule matrix in a harpoon-like fashion. B. stephanieae juveniles therefore promise to be an excellent tool for investigating the cell and molecular processes involved in nematocyst sequestration. Cnidae are among the most complex intracellular secretion products known. Chemoecology. Your US state privacy rights, How Do Jellyfish Sting? - Ocean Conservancy official website and that any information you provide is encrypted Video showing the rapid movement (fractions of a second) of dinoflagellates (brown circles) both into and out of the cnidosac via contractions of the digestive gland in a B. stephanieae juvenile. Step 1: Introduction All cnidarians have nematocysts, also known as cnidocysts. Acquisition and Use of Nematocysts by Cnidarian Predators When discharged, it pierces the skin or, Glutinant: a sticky surface used to stick to prey, referred to as. When touched, the nematocysts release a thread of poison that can be used to paralyze prey. Most data generated or analysed during this study are included in this published article and its additional files. Schematic highlighting our hypothesis for nematocyst sequestration in Berghiastephanieae adults. 2007;73:238. In defensive sequestration systems, however, it is much easier to investigate the cell and molecular specificity of sequestration, since defensive structures and chemicals have been stripped from their original cell. 1999;9:187207. stman C. A guideline to nematocyst nomenclature and classification, and some notes on the systematic value of nematocysts. PubMed J Molluscan Stud Oxford Academic. The dinoflagellates inside the digestive gland are the most visible components of the food due to their distinctive brown coloration (when viewed with DIC optics) and bright autofluorescence (magenta in confocal images). Amongst all marine fauna, Cnidarians are well renowned for producing bioactive peptides which are used in drug development, as they harbor various biological activities; anticancer, anti-inflammatory, immunomodulatory, radical scavenging, anti-parasitic activities, etc. 1. New Insights into the Toxin Diversity and Antimicrobial Activity of the "Fire Coral". International Journal for Parasitology Volume 50, Issues 10-11, September 2020, Pages 763-769 Invited Review A comparison of the structure and function of nematocysts in free-living and parasitic cnidarians (Myxozoa) Benjamin Americus a , Tamar Lotan b , Jerri L. Bartholomew a , Stephen D. Atkinson a Add to Mendeley Comparative morphology and evolution of the cnidosac in Cladobranchia (Gastropoda: Heterobranchia: Nudibranchia). Terms and Conditions, Immature nematocyst incorporation by the aeolid nudibranch Spurilla neapolitana. 2013;408409:114. In contrast to sponges, many cnidarians (phylum Cnidaria) use nematocysts ("stinging capsules"), secreted organelles from nematocytes ("stinging cells"), as defense as well as for food capture and locomotion ( Kass-Simon and Scappaticci, 2002 ). With Berghia stephanieae, these challenges have been overcome due to its lecithotrophic development [41, 42] and dietary preference for Exaiptasia diaphana [40, 42], a cnidarian species that is simple to culture under laboratory conditions [43]. The main function of nematocysts is to produce a harpoon-like thread to inject into their enemy or prey. However, no images of these structures were provided, so independent confirmation is impossible. In most groups that sequester nematocysts, it is hypothesized that these organelles are identified for internalization and storage by specialized phagocytic cells [4, 5]. The architecture and operating mechanism of a cnidarian stinging organelle. 3B). A non-sulfated chondroitin stabilizes membrane tubulation in cnidarian organelles. The Atlantic-Mediterranean genus Berghia Trinchese, 1877 (Nudibranchia: Aeolidiidae): taxonomic review and phylogenetic analysis. [11], The diversity of cnidocytes types correlates with the expansion and diversification of structural cnidocyst genes like minicollagen genes. Google Scholar. This support stems from the fact that both nematocysts (Fig. However, the large contractions and expansions that occur in the stomach and digestive gland can also act to move nematocysts out of the cnidosac (Fig. After the third row of cerata has formed, additional rows will be added symmetrically along the length of the animal. Prior to fixation for histology or antibody staining, we relaxed juveniles of B. stephanieae in a 1 part 7.3% MgCl2 to 2 parts Artificial Sea Water (ASW) solution for ~20min. Front Immunol. Venom from animals such as cnidarians, scorpions and spiders may be species-specific. Regulation of spirocyst discharge in the model sea anemone Nematostella vectensis. Nematocysts are secretory organelles in cnidarians that play important roles in predation, defense, locomotion, and host invasion. However, the extent to which nematocysts contribute to adaptation and the mechanisms underlying nematocyst evolution are unclear. Nematocysts contain coiled threads that may bear barbs. Beauties and beasts: a portrait of sea slugs aquaculture. Grajales A, Rodrguez E. Morphological revision of the genus Aiptasia and the family Aiptasiidae (Cnidaria, Actiniaria, Metridioidea). Cnidaria ( / ndri, na -/) [5] is a phylum under kingdom Animalia containing over 11,000 species [6] of aquatic animals found both in freshwater and marine environments, predominantly the latter. We show that nematocyst sequestration begins shortly after feeding and prior to ceras formation in this species, which will be useful for future studies aimed at visualizing or disrupting the process of nematocyst sequestration. Proc Biol Sci. E. diaphana were purchased from Carolina Biological Supply, Burlington, NC. Acquisition and use of nematocysts by cnidarian predators. The body wall musculature does not show any signs of cnidosac formation (Fig. Inside the cnidosac, multiple sequestered nematocysts (also known as kleptocnides) are clustered within cnidophage cells (Fig. Melo Clavijo J, Frankenbach S, Fidalgo C, Serdio J, Donath A, Preisfeld A, et al. General and fine structure of Aeolidia papillosa cnidosacs (Gastropoda: Nudibranchia). Purestock / Getty Images Cnidarias have an internal sac for digestion which is called the gastrovascular cavity. Unauthorized use of these marks is strictly prohibited. 2014;80:48298. This fact will be useful for studies in B. stephanieae in the long term, because the cerata and cnidosacs at these early juvenile stages are more accessible visually due to less external pigmentation relative to later stages [41]. Nematocyst movement in a Berghia stephanieae juvenile. A Adult animal with many cerata found on the dorsum (Photo credit: Park Masterson). Additional file 3. The site is secure. 28.2A: Phylum Cnidaria - Biology LibreTexts Enzymes include lipolytic and proteolytic proteins that catabolize prey tissues. Our results clearly indicate that in B. stephanieae, nematocyst sequestration begins shortly after feeding and prior to ceras formation, and nematocyst selectivity occurs inside the cnidosac, likely within the cnidophage cells. Post-relaxation, samples were sent to the Electron Microscopy Core Facility at the University of California, San Diego. The nematocyst capsule is produced within a giant post-Golgi vesicle, which is continuously fed by proteins Those studies led to insights into how oxidative environment regulation is involved in the molecular co-evolution of symbiosis [7] and how we might use knowledge of these symbioses to assist in building coral reef resilience [8]. We thank Nicholas Holland for his advice and use of his histological equipment and the U.C. Nat Commun. 2010 Aug 13;285(33):25613-23 We took section images on a Zeiss AxioM2 fluorescence microscope with an attached digital camera (Axiocam 506 color). Inter-partner specificity limits the acquisition of thermotolerant symbionts in a model cnidarian-dinoflagellate symbiosis. Provided by the Springer Nature SharedIt content-sharing initiative. The following day, they moved the samples into fresh 100% Durcupan for half a day at RT and embedded tissues in Durcupan in 60C oven for 36 to 48h. They collected ultrathin Sects. A new species of Aeolidiella Bergh, 1867 (Mollusca: Nudibranchia: Aeolidiidae) from the Florida Keys, USA. They are very short genes containing the characteristic collagen-triple helix sequence, as well as polyproline domains and cystein-rich domains. 2020;11:1066. After eversion, the thread separates from the nematocyst. 2018;15:43. DIC and histology images of early stage Berghia stephanieae juveniles. Nematocyst discharge is controlled by a mechanosensory . Biol Bull. We also confirm the selectivity of nematocysts in the B. stephanieae cnidosac and identify at least three nematocyst types that are found sequestered inside the nudibranch. Vorobyeva OA, Malakhov VV, Ekimova IA. When discharged, it tightly coils around the prey. 2005;47:21823. In these cases, both the branched digestive gland and a small cnidosac are visible. [3], Few papers have modeled the discharge aside from direct observation. The molecular analysis of the nematocyst has from the beginning indicated a collagenous nature of the capsule structure. Invertebr Biol. We first describe the adult cnidosac histologically in B. stephanieae as a baseline for our understanding of development. CAS Minicollagen 1 Ncol-1 polymers assemble on the inner shell while the outer capsule is composed of polymerized NOWA (Nematocyst Outer Wall Antigen) proteins. Cnidarian internal stinging mechanism - PMC As per the nematocyst definition, the phylum Cnidaria is described by the existence of this cell (sea anemones, corals, jellyfish, shydrae, etc. After this expansion phase, nematoblasts develop their capsules. We discuss the importance of these findings below, and propose a hypothesis for nematocyst sequestration in B. stephanieae where the nematocyte (the cell) membrane is removed during early digestion (Fig. 1977;152:392405. In cnidarian-dinoflagellate endosymbiosis, recognition and phagocytosis appear to be mediated by microbe-associated molecular pattern (MAMP)-pattern recognition receptors (PRR) that target a variety of molecular patterns on the cell surface of potential symbionts [3]. These challenges make it more difficult to identify how the early stages of phagocytosis have been modified in cnidarian-dinoflagellate systems. For the subcellular structure in dinoflagellates, see, "The behavioral and developmental physiology of nematocysts", "Nanosecond-scale kinetics of nematocyst discharge", "Neurotoxin localization to ectodermal gland cells uncovers an alternative mechanism of venom delivery in sea anemones", "The Nematocyst: a molecular map of the Cnidarian stinging organelle", "Diversity and evolution of myxozoan minicollagens and nematogalectins", "Fluid Dynamics of Ballistic Strategies in Nematocyst Firing", "Functional characteristics of nematocysts found on the scyphomedusa Cyanea capillata", "Morphological and Molecular Analysis of the Nematostella vectensis Cnidom", "Medusozoan genomes inform the evolution of the jellyfish body plan", "Cnidarian Cell Type Diversity and Regulation Revealed by Whole-Organism Single-Cell RNA-Seq", "Ordered progression of nematogenesis from stem cells through differentiation stages in the tentacle bulb of Clytia hemisphaerica (Hydrozoa, Cnidaria)", "PaxA, but not PaxC, is required for cnidocyte development in the sea anemone Nematostella vectensis", Dangerous marine animals of Northern Australia: the Sea Wasp.