August 18, 2017
Some of the common creatures you encounter while working in your garden are sparkling, wigging, pinkish-brownish tube-like forms, referred to as earthworms. They are found in the moist part of the soil and in waterlogged areas especially after a big storm. To most people, this harmless creature may seem as a bother but it has a very big impact in the everyday food chain.
An earthworm has a cylindrical-like shaped body which is divided into a series of segments referred to as metamerisms. Apart from the segments around the mouth and anal parts, all the other segments have bristle-like hairs which are used to anchor the different parts of the body as it is moving. An earthworm is born with the exact number of segments it will have throughout its life across all species. They have a fleshy lobe that overhangs the mouth and is used to block the seal the mouth when the worm is at rest. For some species, they use this lobe to drag grass and dead leaves into their burrow. The size of an adult earthworm can range from 10mm and 1mm wide, to 3m long to 25mm wide but it all depends on the species.
The Nervous System
Much the same as the rest of its body, the nervous system is also divided into segments; The central nervous system, the sympathetic nervous system and the peripheral nervous system. The central nervous system consists of two ganglia located on either side of the mouth. The brain which is important for its movement is located above the pharynx and if at any case it is removed, the worm will keep moving continuously. If at any case the first ganglion is removed, the worm will stop feeding and burrowing as the ganglion is responsible for the above processes.
Earthworms can either push ahead or backwards depending on the situation. Unlike the normal movements of other creatures, the earthworm deploys a rather unusual method to move forward or burrow into the soil. The worm expands its circular and longitudinal muscles to elongate itself before anchoring its front end into the ground. It contracts the muscles making its body short thus bringing its back-end closer the front end. The worm will repeat this process over and over until it has burrowed a hole big enough to accommodate it or it has reached its destination. Earthworms have no eyes but only rely on their strong senses to touch and light.
The Digestive System
It is divided into many regions with each section serving a specific purpose. The stomach related framework consists of the pharynx, the throat, the crop, the intestines and the gizzard. When feeding, for example, dead leaves or soil enters the worm’s mouth where it is gulped by the pharynx. It passes through the crop and gizzard where excessive calcium is removed. The food then moves into the digestive organs as organ cells in the digestive system discharge liquids to help in the stomach related process. The intestinal divider contains veins where the processed food is absorbed and transported to the other parts of the body.
Earthworm’s Circulatory System
Earthworms’ blood flows only through vessels. The three main vessels used in blood circulation are; the aortic nerves, the dorsal veins and the ventral veins. There are five sets of aortic curves, which have the obligation of directing blood into the dorsal and ventral veins. The dorsal veins are in charge of conveying blood to the front of the worm’s body while the ventral veins are in charge of conveying blood to the back of the earthworms’ body.
Earthworms use their skin to breathe. Oxygen and carbon dioxide go through the earthworm’s skin by diffusion. Diffusion only takes place when the worm’s skin is moist and thus the body discharges mucous to keep it soggy. Worms consequently, should be in moist or damp soil. This is one motivation behind why they normally surface during the evening when it is perhaps cooler.
The Reproduction Process
Earthworms contain both male and female organs and are thus grouped as hermaphrodites. Both sex organs can deliver sperm and egg individually in every worm. Despite the fact they are bisexual, earthworms need a mate to reproduce. The worms have several ovaries that deliver eggs.
Although these creatures are very small, they are of great importance to the agricultural sector. Their burrowing habit enhances the aeration and water absorption in the soil. They also bring underneath soil to the top which is advantageous to farmers as it contains more nutrients for their plants. They are used as bait during fishing and considered as a source of food to different people. In countries like India, some species of earthworms are used in making various medicines.