Dinoflagellata

Dinoflagellata

Dinoflagellata is a diverse group of protists that are primarily marine plankton, but they can also be found in freshwater environments. They are an important component of the aquatic food web and are known for their role in bioluminescence, red tides, and as symbionts in coral reefs.

Characteristics

Dinoflagellates are characterized by their unique cell structure. They typically have two flagella, one that encircles the cell in a groove called the cingulum, and another that extends posteriorly from the sulcus. This arrangement allows them to move in a distinctive spinning motion.

Cell Structure

The cell wall of dinoflagellates is composed of cellulose plates, which form a structure known as the theca. The theca can vary greatly in shape and ornamentation, which is used to classify different species.

Photosynthesis

Many dinoflagellates are photosynthetic and contain chlorophylls a and c, as well as accessory pigments such as peridinin. These pigments give them a golden-brown color. However, some dinoflagellates are heterotrophic and obtain nutrients by ingesting other organisms.

Reproduction

Dinoflagellates primarily reproduce asexually through binary fission, where the cell divides into two identical daughter cells. Some species can also reproduce sexually, forming a resting cyst that can survive harsh environmental conditions.

Ecological Role

Dinoflagellates play a crucial role in marine ecosystems. They are primary producers, forming the base of the food web. Some species are known for forming harmful algal blooms, commonly referred to as red tides, which can produce toxins affecting marine life and humans.

Symbiosis

Certain dinoflagellates, such as those in the genus Symbiodinium, form symbiotic relationships with corals, providing them with nutrients through photosynthesis. This relationship is vital for the health of coral reefs.

Bioluminescence

Some dinoflagellates are capable of bioluminescence, emitting light when disturbed. This phenomenon is often observed in the ocean at night and can create spectacular displays of glowing water.

Taxonomy

Dinoflagellates belong to the phylum Dinoflagellata, which is part of the supergroup Alveolata. They are closely related to other alveolates such as ciliates and apicomplexans.

Notable Genera

• Alexandrium - Known for producing toxins that cause paralytic shellfish poisoning.
• Karenia - Responsible for red tides in the Gulf of Mexico.
• Noctiluca - A bioluminescent species often seen in coastal waters.

References

• Taylor, F.J.R. (1987). The Biology of Dinoflagellates. Blackwell Scientific Publications.
• Spector, D.L. (1984). Dinoflagellates. Academic Press.

External Links

• AlgaeBase
• MarineBio Conservation Society