''Acanthobdella peledina'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of leech-like

clitellate The Clitellata are a class of annelid worms, characterized by having a clitellum - the 'collar' that forms a reproductive cocoon during part of their life cycles. The clitellates comprise around 8,000 species. Unlike the class of Polychaeta, the ...

in the order Acanthobdellida. It feeds on the skin and blood of freshwater fishes in the

boreal Boreal may refer to: Climatology and geography *Boreal (age), the first climatic phase of the Blytt-Sernander sequence of northern Europe, during the Holocene epoch *Boreal climate, a climate characterized by long winters and short, cool to mild ...

regions of northern Europe, Asia and North America.

Taxonomy

The taxonomy of Acanthobdellida has been contentious for many years, but it is now recognized as the sister group to

leech Leeches are segmented parasitic or predatory worms that comprise the subclass Hirudinea within the phylum Annelida. They are closely related to the oligochaetes, which include the earthworm, and like them have soft, muscular segmented bodie ...

es. ''Acanthobdella peledina'' was first described by the German zoologist

Adolph Eduard Grube Adolph Eduard Grube (18 May 1812, Königsberg – 23 June 1880 , Breslau) was a German zoologist. Adolph Eduard Grube, an able worker in many animal groups, was mainly interested in Polychaetes. In 1837 he defended his thesis at the University of ...

in 1851. For a long time, it was believed to be the only species in the order, but in 1966, another species, '' Paracanthobdella livanowi'', was described from the vicinity of the

Kamchatka Peninsula The Kamchatka Peninsula (russian: полуостров Камчатка, Poluostrov Kamchatka, ) is a peninsula in the Russian Far East, with an area of about . The Pacific Ocean and the Sea of Okhotsk make up the peninsula's eastern and we ...

in eastern Siberia.

Description

''A. peledina'' differs from leeches in not having a well-developed sucker at its anterior end; instead, it attaches to its host with about forty hooked

chaeta A chaeta or cheta (from Greek χαίτη “crest, mane, flowing hair"; plural: chaetae) is a chitinous bristle or seta found in annelid worms, (although the term is also frequently used to describe similar structures in other invertebrates suc ...

e (chitinous bristles) borne on its first five segments. It is in fact unique among Hirudinea in having chaetae at all, and also in having a

coelom The coelom (or celom) is the main body cavity in most animals and is positioned inside the body to surround and contain the digestive tract and other organs. In some animals, it is lined with mesothelium. In other animals, such as molluscs, it r ...

(body cavity) divided by

septa The Southeastern Pennsylvania Transportation Authority (SEPTA) is a regional public transportation authority that operates bus, rapid transit, commuter rail, light rail, and electric trolleybus services for nearly 4 million people in five coun ...

into a discontinuous channel. Other ways in which it differs from other leeches are that the body is divided into 29 segments, it lacks a

prostomium The prostomium (From Ancient Greek, meaning "before the mouth"; plural: prostomia; sometimes also called the "acron") is the cephalized first body segment in an annelid worm's body at the anterior end. It is in front of (but does not include) th ...

and a

peristomium The peristomium is the first true body segment in an annelid worm's body in the anterior end. It is directly behind the prostomium and contains the mouth, tentacular cirri, and sometimes feeding palps, which may instead occur on the prostomium. If ...

, and the

nephridia The nephridium (plural ''nephridia'') is an invertebrate organ, found in pairs and performing a function similar to the vertebrate kidneys (which originated from the chordate nephridia). Nephridia remove metabolic wastes from an animal's body. Neph ...

do not have funnels. It has a sucker at the posterior end, and moves in a leech-like fashion by alternately extending its anterior end forward, then clinging on with its hooked chaetae while it brings its posterior sucker close to its front end. The leeches are cylindrical, olive green and about in length.

Distribution

The species has a

distribution and is known from freshwater locations in northern Europe and Asia, and from Alaska.

Ecology

One of the fish in Alaska parasitized by ''A. peledina'' is the

sardine cisco ''Coregonus sardinella'', known as the least cisco or the sardine cisco, is a fresh- and brackishwater salmonid fish that inhabits rivers, estuaries and coastal waters of the marginal seas of the Arctic Basin, as well as some large lakes of tho ...

(''Coregonus sardinella''). The worms were found just behind the pelvic fins with their anterior ends embedded in the skin and muscle tissue below.

References

{{Taxonbar, from=Q4413388 Leeches Animals described in 1851 Taxa named by Adolph Eduard Grube