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Leeches have 10 stomachs and hundreds of teeth!

Let’s know more about the anatomy of this enigmatic marvel



The animal kingdom is filled with remarkable and often bizarre creatures, each with unique adaptations that allow them to thrive in their respective environments. One such creature that stands out for its extraordinary anatomy is the leech, a type of worm famous for its parasitic tendencies. Interestingly, leeches possess ten stomachs, thirty two brain segments and nine pairs of testicles! Moreover, it has several hundred teeth. 

So, let’s understand leeches which are known to humans for thousands of years and have been used by ancient civilizations like the Egyptians and Greeks for medicinal purposes. They have remained largely enigmatic in terms of their detailed anatomical features during antiquity. The Swedish botanist and taxonomist Carl Linnaeus (1707-1778) significantly contributed to the organisation of leech studies, classifying them within the animal kingdom and developing binomial nomenclature.

Subsequently, in the 18th and 19th centuries, naturalists like John Hunter and Georges Cuvier played pivotal roles in shedding light on leech anatomy, behaviour and classification. In more recent times, modern scientific research in fields like parasitology, zoology, and invertebrate biology has used advanced techniques such as microscopy, dissections, and molecular biology to uncover the intricate physiology and anatomy of leeches, advancing our understanding of these fascinating creatures.

The multiple stomachs and what they do with it

While it may sound perplexing, leeches indeed have ten stomachs, a feature that helps them make the most of their meals. Leeches primarily feed on blood, and their numerous stomachs allow them to store and process blood for extended periods between feedings. This adaptation is especially useful when they have to endure long periods of fasting, as they can slowly digest their last meal while waiting for their next opportunity to feed.

Leeches are brainy but not in the way you’d think

The claim that leeches have thirty two brains may seem incredulous, but it’s not entirely untrue. Leeches have a well-developed nervous system that includes thirty two segments, each with a ganglion or a cluster of nerve cells. These ganglia function as individual processing units, capable of performing simple tasks on their own. While this distributed nervous system isn’t quite the same as having thirty two brains in the way humans do, it allows leeches to react quickly to external stimuli, such as changes in temperature, light, or the presence of potential hosts for feeding.

The formidable teeth of leeches

Leeches have several hundred teeth, which they use for attachment and feeding. These are razor-sharp and equipped with a powerful anticoagulant enzyme called ‘Hirudin’. When a leech latches onto a host, its teeth cut through the host’s skin, and the anticoagulant enzyme prevents the host’s blood from clotting. This allows the leech to feed on the blood without interruption. Once the leech is done feeding, it detaches and leaves behind a small wound that may continue to bleed for a while due to the anticoagulant’s effects.

What science says

The fascinating anatomy of leeches has been extensively studied and documented by scientists over the years. Research in the field of parasitology and invertebrate biology has provided valuable insights into the biology and behaviour of leeches. Here are a few key studies and findings:

·        “Anatomy and Physiology of the Medicinal Leech (Sawyer et al., 1982): This comprehensive study delves into the anatomical features, including the nervous system and reproductive organs of medicinal leeches, providing in-depth insights into their biology.

·     Leeches and Their Vertebrate HostsBeyond Bloodletting” (Siddall, 2011): This research explores the ecological and evolutionary relationships between leeches and their hosts, shedding light on their feeding habits and adaptation.

·        “Functional and Comparative Anatomy of the Digestive System of the European Medicinal Leech (Trontelj et al., 2005):  It focuses on the intricate digestive system of leeches, revealing the functionality of their multiple stomachs.

Leeches may be infamous for their blood-sucking tendencies, but their remarkable anatomy is equally captivating. With ten stomachs, thirty mini brains,” nine pairs of testicles, and hundreds of teeth, they are a testament to the diversity of life on Earth. The research and data surrounding these extraordinary creatures continue to provide valuable insights into their biology, highlighting the fascinating adaptations that have allowed leeches to thrive in various ecosystems. While leeches may not be everyone’s favourite animals, there’s no denying that their peculiar features make them a subject of both scientific interest and curiosity.

Diya is a Trainee Correspondent at Apeejay Newsroom. She has just stepped into the professional world of Journalism and Mass Communication with an endemic passion for writing and storytelling. She started her career with an internship at NDTV. Her innate devotion for Art and Literature fuels her determination to persevere.