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Earthworm Anatomy

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  • Last Updated : 29 Jun, 2022

Earthworms, otherwise called rancher’s companion (farmer’s friend) the physical structure contains a place with Annelida phylum. Their home is soil and food is a natural matter. Varieties of the organic entity found in India are Pheretima and lumbricus. They’re rosy brown in variety and their body is in a state of an extended chamber. Nightcrawlers have ring-like fragmented body/metamers that’s their body is isolated into little sections.



Classifications of Earthworms

Kingdom-Animalia: Nightcrawlers are eukaryotic (cells have cores), multicellular living beings. They’ll move and depend on dead plant materials and microorganisms for food.           

Phylum-Annelida: Nightcrawlers have a part with the phylum which contains divided worms. The fragments of the worm’s body, called annuli, are isolated by cross-over separating dividers known as septa. They have numerous slide actions, with those having a part with animal types having organs in the same portions. In certain sorts of annelids, septa are less characterized or even missing.                                       

Class- Clitellata: Worms have a clitellum, a kind of collar that secretes clitella or covers during propagation. The highest of the worm may be a smaller amount evolved than other annelid species.                   

Order- Haplotaxida: The normal worm is assessed under Haplotaxida, which is one in every one of the two sets of Oligochaeta.               

Family: Lumbricidae The normal night crawler encompasses an area with Lumbricidae, which is one of the foremost important families. Around 33 varieties of worms are recognized under this family.           

Genus and Species: The family is for the foremost part acknowledged to be Lumbricus. There are around 4,400 unique forms of worms. You must have the selection to figure out more specific worm’s scientific categorization by limiting it down in light of district and natural surroundings. Neighborhood field guides and natural texts are a serious asset to tracking down the precise scientific categorization of a given worm.


The outer collection of the night crawlers is covered by a thick layer that is non-cellular in nature. This membrane is known as a cuticle. Beneath, the external defensive membrane, there is a layer of the epidermis, beneath that there are two strong layers and afterwards is the deepest layer which is the coelomic epithelium which further comprises a solitary film of glandular columnar epithelium.

Digestive System

The stomach-related framework incorporates a wholesome channel, which is otherwise called the food pipe. It is the longest tube in the worm’s body, which begins from section 1 and goes up to the last fragment.  It begins from the mouth/oral/buccal cavity which is situated from section 1-3, then, at that point, goes through the pharynx, throat which is situated from section 5-7, then solid gizzards which are situated from 8-9 fragments, stomach which is situated from section 9-14, then goes through digestive tract and closures at rear-end. The typhlosole is situated from fragments 26-35 in the digestive system. The fundamental capacity of typhlosole is to increment the surface region for better retention. 

Assimilation is a bit-by-bit process as the food passes by every organ after going into the nutritious trench. Solid gizzards go about as processors and mix the dirt particles and other food matter. 

Circulatory System

Worms have a shut circulatory framework, which means that the progression of blood is shut inside blood vessels. The circulatory framework incorporates hearts, vessels, circles, veins, and blood organs.
There are two varieties of vessels seen in worms 

  1. Veins situated behind the 13th section/digestive district incorporate middle longitudinal blood vessels, digestive blood plexus, commissural vessels, Integumentary vessels, and nephridial vessels. 
  2. Veins situated in the foremost 13 sections are additionally concentrated under three heads-middle longitudinal vessels, hearts and front circles, and veins of the stomach. There are 16 hearts in the worm.

Hearts located in sections 12th and 13th are available on dorsal and oesophageal vessels; horizontal oesophageal hearts. The hearts in fragments 7th and 9th are horizontal hearts. Circle-like vessels situated in the 10th and 11th sections are front circles. They have valves. Blood organs are situated in the 4th, 5th, and 6th sections over the pharyngeal mass and are red in variety. These organs make hemoglobin and blood corpuscles.

Respiratory System

There is no separate system is seen in earthworms for respiration as in humans. Gaseous exchange happens through the moist body surface of the organism, and this is often referred to as the strategy of diffusion.

Excretory System

The excretory framework eliminates squander from the body and in worms, this framework comprises nephridia.
Nephridia are curled cylindrical designs which are situated on the sections of the organic structure. On the premise of their area on the section, there are three forms of nephridia- 

  • Septal nephridia (last 15 Segments)
  • Integumentary nephridia (last 3 segments) 
  • Pharyngeal nephridia (4-6 segments) the basic capacity of those curled designs is to stay up with the body volume of the creature.

 All the styles of nephridia share comparable construction. A bit channel-formed structure is related to nephridia. The capacity of this construction is to ship squander liquids, which are additionally taken out by stomach-related tubes.

Nervous System

Earthworm Nervous System


The nervous system is the regulator of the entire body. A large range of brain reactions (strong and tangible input) are constrained by ganglion cells. These cells are the groups of mass cells. These cells are too organized in portions. They’re gotten along with nerve lines (which are arranged in portion 3 and 4) for the acceptable working of each one of the brain exercises. Nerve ropes branches and covers the pharynx and join focal ganglion cells within the front part, which makes tangible results and orders strong reactions inside the creature’s body. The focal sensory system of the worm is taken into account under two heads.

  • Nerve rings-ring-like circular construction situated in fragments 3rd and 4th.
  •  Ventral nerve cord string-like construction that reaches out up to the last section 

Sensory System

  • They’re organisms without eyes. 
  • They sense the surrounding progressions by means of particular tangible receptor cells.
  • Epidermal receptors are found all around the epidermis. They answer compound upgrades and temperature changes.
  • Buccal receptors answer synthetic boosts. They fill gustatory and olfactory roles and are situated in the buccal chamber.
  • Receptors that are sensitive to light and are located only on the dorsal surface are photoreceptors.

Reproductive System

Earthworm Reproduction System


Since worms are bisexuals, they need both sex organs male and feminine in one body. On the off chance that we discuss male sex organs, earthworms have                         

  • Sets of testicles – situated on the 10th and 11th fragments. They produce sperms. 
  • Testis sacs are situated on the 10th and 11th fragments. Liquid-filled sacs that encompass testis. 
  • Vas-dereferential-situated till the 18th fragment 
  • Two frill organs are situated on the 17th and 19th fragments. 
  • 2 sets of fundamental vesicles to store sperms. Situated at 11th and 12th section. 
  • Male genital pores are situated in the 18th section, within which spermatic pipes and prostatic organs open. 
  • Spermiducal channel found in two sets. Situated in the 10th and 11th sections. 
  • Prostate organ sets of organs that are white in variety and are situated in the 16th-20th section. From every prostate organ, a prostatic conduit emerges. The feminine regenerative framework in worms has- 
  • Oviduct-situated on 14th section. Opens through female genital pores. 
  • 2 ovaries are situated in the 12th and 13th sections. It contains ova. 
  • Spermatheca- Flagon molded for putting away sperms. Situated from 5th-9th portions. Sperms on development return to the testis sac through the periductal channel.

During the hour of sex/lovemaking, two life forms trade their sperms. At that time sperm, eggs, and nutritive liquid gets stored in an organ called a cocoon which is subsequently gathered within the ruin. There’s no hatchling found in their proliferation, direct worms are framed 

Significance of Earthworm to Mankind

As we certainly understand that there are different names by which worms are known, farmer’s buddy/climate engineers. It’s so an aftereffect of the different normal, substance, and physiological changes they pass on to indulge profile. 

  • The most point is that they work on the richness of the soil. 
  • They’re food sources of fishes, frogs, amphibians, moles, and a few macro individuals. 
  • There are many individuals who make money by providing such living beings to research facilities for research purposes.

Conceptual Questions

Question 1: Which elements and organs of the stomach-related arrangement of worms are connected with their eating routine?                                  


Nightcrawlers eat decaying natural material and tiny organic entities ingested together with soil particles. The digestive system of worms has unique designs, including a robust divider and a gizzard, which grind up the food and scratch it against the ingested soil particles. Since annelid processing is barely extracellular, toward the finish of their stomach related framework, nightcrawlers likewise contain designs just like the cecum and therefore the typhlosole, which has the capacity of expanding the retention surface of the system digestorium.

Question 2: What is the clitellum of worms and where it’s found?


The clitellum is an exceptional region of the annelid comprised of rings (metameres) with a regenerative capacity. It fine is also found within the front a part of the creature and is recognized by a lighter tone in contrast with the standard shade of various sections.

Question 3: What is the environmental job of nightcrawlers (Earthworms)? 


Nightcrawlers play a major natural part, as they eat disintegrating natural material. They additionally dig burrows within the earth, permitting the entry of gases and supplements that are helpful for plant roots and other living organic entities. Accordingly, they assume the part as decomposers and manures.                            

Question 4: How do earthworms reproduce? 


Nightcrawlers are androgynous, which means that a solitary worm has both male and female regenerative organs. The male regenerative organ is situated on the fifteenth portion of the worm and so the feminine conceptive organ is on the clitellum. Worms imitate by lying near one another head to tail and adjusting their male pores to clitellum. a pair of designs of nightcrawlers can recreate without tracking down a mate, and the populaces of these worms can develop extremely quickly. Different worm species have their clitellum on various portions which suggests that main nightcrawlers of comparable species can adjust their regenerative organs. within the wake of imitating, juvenile worms are delivered in “cases”, which are strong containers that hold the nightcrawlers until they’re prepared to evoke. Whenever conditions are correct, these cases open, and youthful night crawlers start to want care of and develop.

Question 5: Which kind of nervous system is available in the worm? 


The nervous system of a night crawler comprises the focal, peripheral, and sympathetic nervous systems. The focal nervous system comprises two ganglia, which are associated with the nerve rope. It comprises an engine, tactile and adjustor neurons.

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