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Tuesday, July 13, 2010

Are there leeches

By Mary Margaret
LEECHES or lintah in Malay. The very word is enough to send shivers of terror down the spines of even the bravest. The thought of such creatures inching onto us, sinking their teeth in and sucking in a blood meal is horrifying. It is the stuff of nightmares.
However, if we can overcome our instinctive repulsion, we might begin to wonder about the roles these creatures play in the natural environment.
Are they only predators or are they also prey? Are they intricate components of the food web and the multitude of interlinking cycles of life? Do they bring benefits? Are they related to other animals?
Leeches are invertebrates and a carnivorous type of worm. They are related to the earthworm and belong to Phylum Annelida, Class Hirudinea and Subclass Euhirudinea.
Despite their reputation, they play important roles in a multitude of land, marine and freshwater ecosystems. It is irrelevant that we shudder at the thought of them or base creatures of nightmares on them.
The three orders of leeches are Rhynchobdellae, Gnathobdellae and Pharyngobdellae. Members of Rhynchobdellae are jawless and have a straw-like proboscis (mouth) that can be injected into prey. Members of Pharyngobdellae are toothless worm leeches, which consume their prey whole.
Gnathobdellae have jaws armed with teeth and these are the ones that are of direct interest to us humans, as they are the bloodsuckers. These jawed leeches generally have specific prey — mammals, fish, amphibians, reptiles and birds.
HIRUNDO MEDICINALIS: This native European species has been used for thousands of years by medical practitioners.

Leeches, as an intricate part of the world, not only eat but are also eaten. These creatures are preyed upon mainly by fish and birds.
Like other worms, leeches have segments and are hermaphroditic with both male and female sex organs. Leeches, like other worms, have a clitellum at the side of their body. Glands in this organ secrete a cocoon to protect the eggs. They have well-developed eye spots, ocelli, which help them identify prey. Leeches inch along with suckers at the front and back.
These invertebrates go through metamorphosis — eggs, larvae and finally emerge as adults. Leeches are good parents. The eggs are protected by a cocoon that is produced by citellum that slides of the head, but picks up the fertilised eggs that are along the leech’s body.
HERMAPHRODITES: Like other worms, leeches have both male and female sex organs.

The cocoon is attached to a hard surface. In some species the cocoon becomes hard and dry; in others a spongy layer is formed to prevent dehydration.
Leeches are found in Sarawak’s jungles and with the exception of a single species from Borneo, leech bites are not painful. Leech saliva contains, for example, a number of components that are potentially medically beneficial: antibiotics, anti-coagulant to prolong bleeding and increase permeability of skin.
The most famous leech is the medical leech Hirundo medicinalis, a native European species which is threatened in its original range. This leech has been used for thousands of years and continues to be used by medical practitioners and in order to get sufficient numbers it is farmed.
A newspaper report on April 13, indicated that it might be raised in the Belaga area.
I don’t suppose the next time we walk in the jungle and we observe a leech standing and waving looking for prey, that we will be keen on being preyed on to join the many interlinking food webs, but that is life.

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