INVERTEBRATE ZOOLOGY IN THREE BOOKS - BOOK 2 - H.I. Shcherbak - 1996

PHYLUM ANNELIDA

CLASS LEECHES (HIRUDINEA)

SUBCLASS ARCHIHIRUDINEA

This subclass includes only a single order, Acanthobdellea, comprising one genus with two species. Each of their first five segments bears four pairs of setae (see Fig. 30, a); they possess a well-developed coelom with septa between the somites and a Circulatory system, and The Stomach lacks blind cecal pouches. A small proboscis is present, while the anterior sucker is poorly developed or absent. Body length is up to 30 mm.

Both species are parasites of salmonid Fishes found in cold, oxygen-rich freshwater bodies in high latitudes of the Northern Hemisphere. Acanthobdella peledina is found on salmonids in the waters of Scandinavia, the tundra and forest-tundra zones of Russia, and Alaska. A. livanovi is known only from Kamchatka and Chukotka.

True leeches lack setae, their anterior sucker is well developed, and the coelom takes the form of a lacunar system that partially or entirely replaces the circulatory system. This subclass includes two orders.

Order Rhynchobdellea. Body size is small (5–30 mm, rarely up to 80 mm in length). Exclusively aquatic organisms; they possess a proboscis; the circulatory system is generally well developed. There are three rings per somite. Fertilization is spermatophoral. Parental care is characteristic of many species: their eggs are attached to the ventral side of the leech; the juveniles also develop there, and the adult protects them for some time (Fig. 37).

Widely known throughout Ukraine and the Mediterranean region is the so-called turtle leech (Haementeria costata), which has a broad, flattened body. Coloration ranges from green to brown. Several rows of papillae run along the body. It parasitizes pond turtles and can also feed on the Blood of birds and even humans. Species of the genus Glossiphonia have a body shape similar to the previous species, though they are smaller in size. They prey on Mollusks, insect larvae, and occasionally other leeches.