The crop works like an expandable storage compartment and allows the leeches to store blood up to
five times its body size.
Descriptions of the different stages of Haemadipsa's attack :
Haemadipsa picta is known locally as 'timtang' or 'pacat daun' (leaf leech), because it is usually
found on leaves of lower vegetation. Can grow to about 4cm long when stretched out, and sports
alternating yellow/orange and black stripes. Bite can be felt by humans.
When a leach locates its prey, it punctures the skin using salivary glands producing an anticoagulant
to regulate blood flow. This is the reason why leech bites may continue to bleed several hours after
the leech has been removed. A leech may absorb several times its own weight in blood before
dropping off. It is thought that one meal can last up to six months or more.
As in the pic, the tiger leech is curled in a resting position, in a state of physiological inactivity upon
the upper surface of a leaf on low vegetation in the lowland forest. Two suckers are present in its
body, one surrounding the mouth, the other at the posterior end which the leech use to attach itself
at the surface. In the pic the anterior end is folded beneath itself and the posterior sucker permit it
to estabilish itself on the leaf, waiting for a potential host to attack. When the leech detects a passing
host it extends the rest of the body out and drops from the leaf and attaches to its host using an oral
sucker.
Haemadipsids (commonly called jungle leeches) which attack humans are a feature of rain forest
from Madagascar and India through South-East Asia to the West Pacific Australia. Haemadipsa
zeylanica is mainly a ground-level species, while Haemadipsa picta (Tiger leech) climbs one or two
metres up into the undergrowth. Haemadipsids like the tiger leech forage on the ground, along the
branches and leaves of underbrush and other exposed surfaces. They attach themselves to these
surfaces by their larger posterior sucker and stretch themselves out, with the oral sucker
(surrounding the mouth) ready to attach to a passing host. Detecting of host rely on the multiple
sensory mechanisms. According to some researchers, these leeches utilize two eyespots on the top
of their heads to detect movement through changes in both light and shadows. Field experiments
carried out by Kmiecik, O'leary and Yiing, suggest that movement and heat of the prey play an
important role in leech attraction. Therefore it could be possible that other factors such as smell,
sound and combinations of multiple factors interact making more complicate the situation.
The species are distinguished in the field, since H. picta has a conspicuous yellow strip and inflicts a
painful bite, in contrast to the uniformly coloured H. zeylanica whic causes no pain because of the
inoculated anaesthetic substance.
Although these leeches don't transmit human disease, wounds can be susceptible to infections,
especially if their removal is not correct. For example, commonly, many people utilize some
unappropriated techniques to remove a leech, utilizing a flame, a lit cigarette, salt, or caustic
chemicals such as alcohol, or insect repellent. However, these techniques, although may be appear
efficacious, could instead result in possible infections. In fact these technique may lead the leech to
regurgitate its stomach contents into the wound and quickly detach. The vomit may carry disease
and increase the risk of infections. Simply pulling a leech off by grasping, it can also cause
regurgitation and adds further risks.
There is not a guaranted method of preventing leech bite but if bittening happens, the best trick for
removing the leech is using a fingernail or a flat object to break the seal of the oral sucker at the
anterior end of the leech, repeating with the posterior end, then flicking the leech away. As the
fingernail or the object is pushed along the person's skin against the mouthpart of the leech, the
suction of sucker's seal is stopped, and the leech should detach its jaws.
Like in the pics bleeding could continue for long time, due to the leech's anti-clotting enzyme.
However the best technique to avoid the attack by these land leeches is the prevention. In my
opinion the most reliable method to defense ourself is to cover teh exposed skin and utilize good
insect repellents in order to prevent bites.
Since leeches commonly reach our more delicate parts of the body passing through our feet and
legs, white or light colour leech socks could be useful in preventing bites. Leech socks should be
pulled over the wearer's trousers to prevent leeches reaching the exposed skin of the legs and
attaching there or climbing towards the torso. Essential is check out costantly our body, also after
we come back home. Haemadipsa spp. occurs commonly throughout the year in alluvial and in
Dipterocarp forests, while occur rarely in heath forests (Kerangas) and never in forest over
limestone.
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