‘Limatik’ Encounters – 3

To paraphrase what Robert Fulghum (1990) said, “All people really need to know, they learned in kindergarten.” In my time, Kindergarten was more of an exception than the rule and so I, like most of my generation, instead went straight to Grade I. Yet essentially the same sets of first lessons and questions as those of today’s tots were asked or taught. Some remained in our minds, and will never be outgrown. Well, growing up, some of us forget some songs of our childhood.

As young kids, we were taught a nursery rhyme that included lines like All things bright and beautiful, All creatures great and small, . . .” from a song by Cecil F. Alexander published in 1848. It seems like everything has to have a purpose, just like tools and other things at home, but the thought has extended to natural objects and yes, “all creatures great and small.”

So back to leeches, I have been asked, “What is their purpose in the environment?” Purpose is something philosophical that unavoidably dwells on the spiritual and I would avoid touching that for this short piece. I would just interpret “purpose” in the biological / ecological sense.

Like many other plants, animals, and other organisms that we ignore or annoy us, leeches are part of that very wide range of our rich biological diversity. Most leeches are considered parasites because they don’t really kill their hosts. Their hosts from which they obtain blood are usually mammals, occasionally birds, and less frequently, reptiles. By logic, therefore, they could also be biological indicators. If in a certain place, where the forest cover is still good, and which is not usually reached by many people, there would be lots of leeches, then one could infer that vertebrate wildlife would still be abundant there. Possibly, wildlife species like wild pigs, deer, cloud rats or other mammals which could serve as “blood donors” to the leeches.

Where and why are leeches abundant in Mount Makiling? A trekker usually first notices them up the area going to and around Mudspring. Sometimes there can also be found in the Flat Rocks area. On the ‘College’ (northeastern) side, they are common along the trail to Peak 2, especially starting from Station 14, and during the rainy season, there would be leeches starting at Station 12. They are probably most notorious on the Santo Tomas side, particularly inside the less visited crater area or the Greater Sipit Watershed. There, reports of leech attacks in the eyes, are not uncommon. The rains and the rainforest environment really encourages them. Possibly, vertebrate wildlife – their blood donors – may still be in relatively good numbers. Of course, local tourists can also provide their required blood meal or diet.

Three out of every four hirudineans are blood-feeders. Why blood? We’ll try to answer that next time. What about that “one of every four” – what do they eat? Well, those other leeches feed on other animals smaller than them and are therefore predators. Their prey includes earthworms (their distant relatives) or tiny insects.

So, what’s is the purpose of leeches? Again, I won’t give them a purpose. Purpose connotes usefulness and/or benefit from the human or anthropocentric point of view. I would rather say all species have roles in the environment. All native species are important because of their connectedness to all the living and non-living components of their environment. In much the same way as no single human soul can save our planet, because we all have to do our part. – Jun Lit

Cloud-covered Mount Makiling as viewed from the Institute of Plant Breeding in U.P. Los Baños.
What I tentatively call the Makiling tiger leech, sitting on a leaf and waiting for unwilling blood donors. (Photo taken with the assistance of Kirk J. Taray)

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