Pheretima darnleiensis

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Pheretima darnleiensis
Systematics
Class : Belt worms (Clitellata)
Subclass : Little bristle (Oligochaeta)
Order : Earthworms in the broader sense (Crassiclitellata)
Family : Giant Earthworms (Megascolecidae)
Genre : Pheretima
Type : Pheretima darnleiensis
Scientific name
Pheretima darnleiensis
( JJ Fletcher , 1886)

Pheretima darnleiensis is a type of little bristle from the family of Megascolecidae (giantearthworms) in the order of Crassiclitellata (earthworms in the broader sense), which iswidespreadin Southeast Asia and reaches a length of 70 cm.

features

Pheretima darnleiensis is usually about 4.5 cm to 40 cm, in some areas up to 70 cm long and 2.5 mm to 6 mm wide, with adult animals having about 70 to 180 segments. About 25 to 66 bristles are distributed evenly on each segment , the number of which is greater in the rear segments than in the front. The skin of the giant earthworm is gray-blue in color with a darker clitellum and a greenish sheen, but preserved animals take on a brown color.

The hermaphrodite usually has four, rarely five pairs of receptacula seminis , which are located in the segments from the 6th to the 9th, rarely also in the 5th segment and are about a fifth of the total circumference of the body cross-section apart. The two male genital orifices on the 18th segment are also about a fifth of the circumference laterally apart. There are no markings on the genitals. The giant earthworm has two pairs of testicles that are located in segments 11 and 12 in scrotums. The large, grape-like prostates lead in segments 17 to 19 into copulation bags, each with a conical penis . The ovaries are tightly packed as a pair in the 13th segment with strands of ice, while ice sacs are missing.

There is a gum stomach that includes up to four segments between the 7th and 11th segment. In or next to the 27th segment there are two simple intestinal blind sacs. In the closed blood vessel system there is only one single back vessel and hearts in segments 10 to 13.

distribution

Pheretima darnleiensis is widespread in Southeast Asia , especially in the Indomalayan - Australasian archipelago ( Singapore , Sumatra , Java , Bali , Borneo , Sulawesi , Philippines , Christmas Island , neighboring islands of New Guinea such as Darnley / Erub ) and on the Malay Peninsula . The giant earthworm is likely to have been introduced to the Caroline Islands and Fiji , but also to Darnley . On the slopes of Kinabalu in Borneo ( Malaysia ), the annelworm, which is native to this area, reaches a length of 70 cm.

Life cycle

Like other belt worms - as are all earthworms - Pheretima darnleiensis is a hermaphrodite , whereby two individuals exchange their sperm during mating and store the sperm of the respective sex partner in their own receptacula seminis . Unlike the European earthworms , but like other giant earthworms , Pheretima darnleiensis has several cone-shaped penises for mating . With the help of the clitellum , a cocoon is formed after copulation , in which the eggs are laid and inseminated with the partner's temporarily stored sperm. The embryos develop into small finished earthworms in the cocoon.

Habitat and way of life

Like other Crassiclitellates, Pheretima darnleiensis is a soil dweller and substrate eater , digesting the organic components of the ingested substrate and loosening and aerating the forest soil through its burial activity. It can often be seen during and after heavy rains, while otherwise it hangs in the self-dug tubes underground.

Predators

Among the main predators of the giant earthworm include predatory terrestrial Riesenegel as to the throat leech species belonging Gastrostomobdella monticola and on the Kinabalu living Mimobdella buettikoferi which, like this dig on the hunt for earthworms through the floor.

literature

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