Parmales

The Parmales are a group of marine planktonic algae belonging to the class Bolidophyceae, within the heterokonts (also known as stramenopiles). They are characterized by their distinctive silica plate-like structures called scales or shields, which form an external cell covering or lorica. These scales are composed of two types: a "valvular plate" and "accessory plate".

Parmales are typically very small, in the size range of a few micrometers, and are found in diverse marine environments, including both coastal and open ocean waters. They are particularly common in polar and subpolar regions, where they can contribute significantly to the phytoplankton community.

Historically, the Parmales were difficult to classify due to their small size and the challenges of observing their delicate silica structures. Their taxonomic classification has been revised significantly over time, and they are now considered to be more closely related to the Bolidophyceae than to other heterokont groups to which they were previously assigned.

The ecological role of Parmales is still under investigation, but they are believed to be important primary producers and a food source for small zooplankton. They also play a role in the marine silica cycle, as their silica scales eventually sink to the seafloor after the cells die.

Further research is ongoing to better understand the diversity, distribution, and ecological significance of Parmales in marine ecosystems.