Definition

The gymnodinium is a genus of the dinoflagellates. They are marine organisms and are mainly present in freshwater. The gymnodinium sp is also known as a naked dinoflagellate. This is because no armor is present on the body of the gymnodinium sp as it is present on the body of other organisms in their class. The gymnodinium are known as red dinoflagellates and they are the reason for the cause of the red tide phenomenon. We will learn more about the gymnodium and the dinoflagellates structure. The gymnodinium has a mixotrophic type of nutrition. They are single-celled eukaryotic organisms. They are also considered to be photosynthetic in nature. 


Morphology

Dinoflagellates are unicellular organelles. They possess two dissimilar flagella that arise from the ventral side of the cell. A ribbon-like transverse flagellum is needed. This is because it has multiple waves that beat to the cell’s left and the longitudinal flagellum beats in a posterior way. The transverse flagellum may be a wavy ribbon during which only the fringes undulate from base to tip. This is because of axensome. The axonemal edge has simple hairs which will be of varying lengths. The flagellar movement produces forward propulsion and also a turning force. The longitudinal flagellum is comparatively conventional in appearance, with few or no hairs. It beats with just one or two periods to its wave. The flagella dwells surface grooves, the transverse one within the cingulum and therefore the longitudinal one within the sulcus, although its distal portion projects freely behind the cell. In dinoflagellate species with desmokont flagellation, the two flagella are differentiated as in dicynodonts, but they are not related to grooves.

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Dinoflagellates Structure

The Dinoflagellates structure has a posh cell covering called a cortex, composed of a series of membranes, flattened vesicles called alveolar, and related structures. In armored dinoflagellates, theca or lorica is the armor that is prepared by the support of overlapping structures. These occur in various shapes and arrangements, counting on the species and sometimes on the stage of the dinoflagellate. Conventionally, the term tabulation has been wont to question this arrangement of thecal plates. The plate configuration is often denoted with the plate formula or tabulation formula. Fibrous extrusomes also are found in many forms. alongside various other structural and genetic details, this organization indicates an in-depth relationship between the dinoflagellates, the Apicomplexa, and ciliates collectively mentioned because of the alveolates.


Classification

Dinoflagellates of the gymnodinium sp protists are classified using both the International Code of Botanical Nomenclature and therefore the International Code of Zoological Nomenclature (ICZN). About half of living dinoflagellate species are autotrophs possessing chloroplasts and half are non-photosynthesizing heterotrophs.


The peridinin dinoflagellates, named after their peridinin plastids, appear to be ancestral for the dinoflagellate lineage. Almost half all known species have chloroplasts, which are either the first peridinin plastids or new plastids acquired from other lineages of unicellular algae through endosymbiosis. The remaining species have lost their photosynthetic abilities and have adapted to a heterotrophic, parasitic, or kleptoparasitic lifestyle.


Most dinoflagellates have a dikaryon. Dinoflagellates with a dikaryon are classified under Dinokaryota, while dinoflagellates without a dikaryon are classified under Syndiniales.


The dinoflagellate nucleus was termed ‘mesokaryotic’ by Dodge. Due to its possession of intermediate characteristics between the coiled DNA areas of prokaryotic bacteria and therefore the well-defined eukaryotic nucleus. This group, however, does contain typically eukaryotic organelles, like Golgi bodies, mitochondria, and chloroplasts.


Mechanism of Capture

Very diverse types of mechanisms of capture and ingestion in dinoflagellates. Several dinoflagellates, both thecate (e.g. Ceratium hirundinella, Peridinium globulus and non-thecate (e.g. Oxyrrhis marina, Gymnodinium sp. and Kofoidinium spp, draw prey to the sulcal region of the cell either via water, currents found out by the flagella or via pseudopodial extensions, and ingest the prey through the sulcus. In several Protoperidinium species, like conicum, an outsized feeding veil — a pseudopod called the pallium — is extruded to capture prey which is subsequently digested extracellularly. Oblea, Zygabikodinium, and Diplopsalis are the sole other dinoflagellate genera known to use this particular feeding mechanism. Katodinium fungiform, commonly found as a contaminant in algal or ciliate cultures, feeds by attaching to its prey and ingesting prey cytoplasm through an extensible peduncle. Two related species, polykrikos kofoidii and neatodinium, shoot out a harpoon-like organelle to capture prey. The feeding mechanisms of the oceanic dinoflagellates remain unknown, although pseudopodial extensions were observed in Podolampas pipes.

FAQs (Frequently Asked Questions)

1. Explain the Lifecycle of Dinoflagellates.

Answer: The dinoflagellates have a haplontic life cycle. Amphimixis also occurs, though this mode of reproduction is merely known during a small percentage of dinoflagellates. This takes place by fusion of two individuals to make a zygote, which can remain mobile in typical dinoflagellate fashion and is then called a plant zygote. This zygote may later form a resting stage or hypnozoite, which is named a dinoflagellate cyst or dinocyst. After germination of the cyst, the hatchling undergoes meiosis to supply new haploid cells. Dinoflagellates appear to be capable of completing several DNA repair processes which will affect different types of DNA damage.

2. Explain Nutrition in Dinoflagellates.

Answer: In dinoflagellates: phototrophy, mixotrophy, and heterotrophy are seen. Phototrophs are often photoautotrophs or auxotrophs. Mixotrophic dinoflagellates are photosynthetically active but also are heterotrophic. Facultative mixotrophs, during which autotrophy or heterotrophy is sufficient for nutrition, are classified as amphitropic. If both forms are required, the organisms are mixotrophic sensu stricto. Some free-living dinoflagellates don't have chloroplasts but host a phototrophic endosymbiont. Food inclusions contain bacteria, blue-green algae, small dinoflagellates, diatoms, ciliates, and other dinoflagellates.