Acantharea is a class of radiolarian protists which are distinguished and classified by their “skeletons”. These “skeletons” are composed of strontium sulfate crystals and can take the form of either ten or twenty diametric or radial spines. Their central capusle is made up of microfibrils that are arranged into twenty plates, each with a hole though a spine projects. Microfibrillar cortex’s linked to the spines are also present and assist in flotation.
Of the four subclasses of Acantharea each can be distinguished by whether their spines are radial/diametric and how they are positioned.
Image(s): David Patterson, Linda Amaral Zettler, Mike Peglar and Tom Nerad