"Blue tide of dinoflagellates" by BMC Ecology is licensed under CC BY 2.0
Definition of Pyrrophyta (Fire Algae / Dinoflagellates)
The phylum Pyrrophyta is often called the Dinoflagellates, so named because of the movement of the two whip-like flagella (in Latin, dino means whirlpool). Dinoflagellates consist of about 1,100 species, mainly living in sea water, although some species live in fresh water. Dinoflagellates are motile unicellular algae, with the main characteristic of having gaps and grooves on the outside of the envelope that surrounds the cell wall.
Some types of dinoflagellates do not have a cell wall, but most have a cell wall that is divided into polygonal cellulose plates that are closely connected to each other. Pyrrophyta are also often called fire plants or fire algae.
Why are Pyrrophyta or Dinoflagellates called fire algae?
Phylum Pyrrophyta is called fire algae because it has a shell that contains phosphorus which is able to emit a bright red light like fire or blue green which is very beautiful, especially in dark conditions at night in sea water. This phenomenon of light fluorescence is called bioluminescence . An example is Noctiluca sp. , and Ceratium sp.
The appearance of red color is because these protists contain a lot of carotenoids , so their appearance is more often gold, brown or red than green. Pyrrophyta or Dinoflagellates mostly have non-contractile vacuoles, chloroplasts, and have chlorophyll a and b.
Dinoflagellate green chlorophyll is usually covered by a red pigment that helps capture light energy. When the water is warm and rich in nutrients, the Dinoflagellate population will explode. The number of dinoflagellates will be so large that the water will be colored red by body color. This event is known as a red wave ( red tide ).
Autotrophic dinoflagellates are a common type of phytoplankton. They are excellent producers of biomass and oxygen. Some dinoflagellates which are photosynthetic, live in symbiosis on the bodies of several types of corals, sea anemones, flatworms, and giant clams.
Some dinoflagellates are also heterotrophs. They live by ingesting organic matter and other living cells. In addition, a small proportion of Dinoflagellates can be parasitic on the bodies of various marine animals, for example Protogonyaulax catenella .
Pyrrophyta (Fire Algae / Dinoflagellates) Body Structure
To understand the parts of the cell structure of Dinoflagellates and their functions, please look at the pictures and explanations below.
■ Dinoflagellata is essentially motile unicellular organisms and berflagel two (biflagella), golden-brown colored, and including photosynthetic protists. Although the dominant color is golden brown, there are also yellow, green, brown and even blue ones. Some of them are non-motile, do not have flagella, are ameboid, and are fibrous.
■ cells are generally covered by a coat or a rigid plate made of cellulose arranged artistically sculpted. This arrangement of plates is called armor plate or armor plate .
■ dinoflagellates have two slits or grooves are longitudinal grooves (longitudinal) called the sulcus (groove) and a circular groove (transverse) known as the cingulum or annulus or corset.
■ Two flagella in different Dinoflagellata (heterokonts), the flagellum transverse and longitudinal flagellum. Longitudinal flagella are smaller and smoother and point posteriorly and are located in the sulcus . While the transverse flagella is shaped like a ribbon and is located on the cingulum . These two types of flagella move in different directions, resulting in a whirlpool when the Dinoflagellates move.
The nucleus is large and named mesokaryon by Dodge (1966). This part of the chromosome lacks histones or RNA.
■ plastids or chromatophore have chlorophyll a and chlorophyll c.
■ vesicles located at the bottom of the cell memberan.
■ vacuole non-contractile called pusule located near the base of flagella. This pustule is useful for floating on the water surface and osmoregulation. There are no contractile vacuoles in Dinoflagellates.
Characteristics of Pyrrophyta (Fire Algae / Dinoflagellates)
Pyrrophyta or Dinoflagellates or Fire Algae have general characteristics or characteristics, which are as follows.
■ Unicellular (single-celled)
■ Characteristically motile (active)
■ It has a flagellum (feather whip)
■ Have a real cell wall composed of plates that contain cellulose, but there are some who do not have cell walls, for example Gymnodinium sp.
■ Have a cell with a characteristic that is there are gaps and grooves as well as in the cells are the plastids containing pigment chlorophyll a and c, as well as carotenoids that the yellowish brown in color.
■ Characteristically autotrophic (able to perform photosynthesis or are photosynthetic) and serves as phytoplankton in the ocean.
■ Characteristically are heterotrophic life by way of ingesting organic matter and other living cells.
■ There are also nature as a parasite that lives in a way attached to the body of a variety of marine animals, for example Protogonyaulax catenella .
■ Live free or symbiosis on the body, some corals, sea anemones, flatworms, and shellfish raksaksa.
■ In some species, cangkagnya containing phosphorus that fluoresces at night.
■ Most berhabitat in seawater but those that live in fresh water.
■ Have non-contractile vacuole which serves to float and osmoregulation.
Classification of Pyrrophyta (Fire Algae / Dinoflagellates)
Because dinoflagellates can be seen as both plant-like and animal-like, their classification has been debated among botanists, zoologists, and paleontologists. The most widely accepted classification scheme is that all dinoflagellates are members of the kingdom Protista, the division Dinophyta, and the class Dinophyceae.
Dinoflagellates were then included in the group of algae (plant-like protists) namely the phylum Pyrrophyta and classified into many orders, genera, and species based on characteristics such as feeding behavior, composition of their outer plate, overall anatomy and physiology.
Pyrrophyta (Fire Algae / Dinoflagellates) Reproduction Methods
Like Euglenophyta , Pyrrophyta also reproduce only asexually, namely by dividing, but some types can produce cysts (resting stage) which are sexual. The cyst will then germinate to produce a new individual under suitable conditions.
Examples of Pyrrophyta or Dinoflagellate species
Dinoflagellates consist of about 1,100 species, mainly living in sea water, although some species live in fresh water. Examples of the most common Dinoflagellate species are Pfiesteria piscicidia, Gonyaulax catanella, and Noctiluca scintillans. The following is an explanation of the three types of Dinoflagellates.
■ Pfiesteria piscicidia is a dinoflagellate species are often found off the coast of North Carolina. Scientists have concluded that it is responsible for killing large numbers of fish by secreting poison. This species has an interesting feeding strategy. It is known to use poison to kill fish then wait for it to consume tissue that sloughs off from decaying organisms. This makes it one of the heterotrophic species of several dinoflagellates.
■ Gonyaulax catanella is dinoflagellate revolving when they move to use two of their flagella. They are also one of the well-known luminous species of dinoflagellates, as they give off a blue-green glow in the waters they inhabit.
■ Noctiluca scintillans are heterotrophic dinoflagellate species that feed on plankton found in estuaries and shallow areas of the continental shelf. This species is often referred to as marine sparkle because it exhibits bioluminescence and becomes very bright when disturbed in water.
The Role of Pyrrophyta or Dinoflagellates
Dinoflagellates often cause an interesting phenomenon in the sea, which can produce a sudden red color of the sea. This phenomenon is often called tidal / wave red or " red tides ". These conditions contain a toxin produced by certain dinoflagellates and can poison fish, shellfish, and sometimes humans.
Toxic red tides can usually occur after the population density of certain dinoflagellates increases sharply ( blooming ). Types of Dinoflagellates that can produce toxic red tides, including Gymnodinium and Protogonyaulax. The toxins or poisons produced by these species are usually neurotoxins or neurotoxins, or can cause the rupture of red blood cells.
When a red tide occurs, thousands of fish suffocate as a result of their gills being clogged or deprived of oxygen by billions of dead and decaying dinoflagellates. However, oysters and mussels "feast" by filtering millions of their food in the water. In this process, their bodies will collect the neurotoxins produced by Dinoflagellates in large enough quantities.
In this situation, Dinoflagellate toxins can accumulate in the body of oysters or mussels without causing the death of the animal. However, if the mollusk is eaten by humans, poisoning can occur in humans who eat it. Therefore, the consumption of shellfish is often avoided during the summer, which is the season when the population of Dinoflagellates increases sharply.
