Gregarinasina

Gregarinasina is a subclass of Apicomplexa, a large phylum of parasitic protists. Members of this subclass are known as gregarines, which are primarily parasites of invertebrates, particularly annelids, arthropods, and mollusks.

Morphology

Gregarines are characterized by their elongated, worm-like shape. They possess a unique structure called the epimerite, which is used for attachment to the host's cells. The body of a gregarine is divided into three parts: the epimerite, the protomerite, and the deutomerite. The protomerite and deutomerite together form the trophozoite, the feeding stage of the organism.

Life Cycle

The life cycle of gregarines typically involves both sexual and asexual reproduction. The cycle begins with the sporozoite, which infects the host. Inside the host, the sporozoite develops into a trophozoite. Trophozoites can undergo schizogony, a form of asexual reproduction, to produce more trophozoites. Eventually, trophozoites differentiate into gamonts, which pair up in a process called syzygy.

During syzygy, the gamonts form a gametocyst, within which gametes are produced. The gametes fuse to form zygotes, which then develop into oocysts. The oocysts are released from the host and undergo sporogony to produce new sporozoites, completing the cycle.

Ecology

Gregarines are found in a wide range of environments, wherever their invertebrate hosts are present. They play a role in controlling host populations and can influence the ecology of their environments. Gregarines are often studied for their interactions with their hosts and their potential impact on ecosystems.

Classification

Gregarinasina is divided into several orders, including:

• Eugregarinorida
• Neogregarinorida

Each order contains various families and genera, with Lankesteria being a notable genus within the group.

Related pages

• Apicomplexa
• Protist
• Parasitism