Tag: earthworm

Chaeta or cheta is a chitinous bristle or seta found on an insect, arthropod or annelid worms such as the earthworm. They function in locomotion. In Pheretima, chaeta is about 0.25 mm long. 

Gustoreceptors are found in the epithelial of the buccal cavity,these cells have sensory hair like processes and their nuclei lie below the middle part of the cells. These receptors severs to smell (olfactory receptors) for taste (gustoreceptors). Earthworms can smell different types of decaying food. Hence gustoreceptors are present in the buccal cavity. 

An earthworm has 100 to 150 body segments, each having muscles and bristles. An earthworm's setae are so tiny, they're almost invisible. He uses them to anchor himself while navigating in the soil, or when a bird is trying to pull him from the ground. The setae is a stiff structure resembling a hair or a bristle, especially in an invertebrate.

Earthworms are segmented and are externally covered by rings that encircle the body. Earthworm is divided into segments 100-200 segments similar segments called somites or metameres. Segments are separated from each other by distinct ring-like grooves. External segmentation corresponds to the internal segmentation of the body. Each segment of the group of segments can become specialized to perform a particular function.

• The Earthworm’s skin is protected by a thin cuticle and kept moist by a slimy mucus.  This lets it absorb the oxygen it needs and expel carbon dioxide.  If a worm is dried up by the sun, it will die because the exchange of gases can’t take place.
  
• Asphyxia is the condition where the body either doesn't get enough oxygen to continue normal function or has too much carbon dioxide to function properly. Without adequate oxygen, nerve cells in the brain begin to die in about 2-4 minutes, and cell death is irreversible. 
  

• Except for the first, clitellar and last segment, all the other segments have eight setae located around each segment. 
• The setae look like small bristles sticking out of the earthworm’s skin. The setae can be retracted and are for moving through the soil. The bristle-like setae anchor the segments as they crawl.
  

Ureotelic organisms are those that excrete nitrogenous waste in the form of urea. Earthworms are ureotelic since their nitrogenous waste composition consists of 40% urea and 20% ammonia.