Nervous system in earthworm

 

Do earthworms have nervous system?

  • Earthworm has a well-developed nervous system.
  • The nervous system is metamerically segmented.
  •  The nervous system is divisible into central, peripheral and autonomic nervous system (sympathetic nervous system).

The nervous of earthworm is well developed. It consists of  three parts  

1)Central nervous system

 2)peripheral nervous system  

3)sympathetic nervous system or automatic N S



1 central nervous system it consists of cerebral ganglia circumpharyngeal connecting software engineer ganglia and ventral nerve cord. A of closely white pear shaped cerebral or subphapharyngeal ganglia forming the brain lies dorsally in the third segment in the the depression between the buccal cavity and the pharynx. A of thick stout parapharyngeal connective passes from them literally embracing the parents and meeting mental in a of fused software engineer ganglia line Beneath The pharynx in fourth segment in this world complete nerve collar on nerve ring formed around the pharynx. 

The ventral nerve cord arising from the sub pharyngeal ganglia,runs backward in the mid ventral line to the posterior end of the body. In each segment at present a slight and enlargement or ganglion. Though control knob COD APL to be single but it really doubled consisting of two compactly United right and left half as seen in the transverse section. The segmental ganglion also represent the fusion of fear of ganglia one belonging  to  half of the ventral nerve cord.



2 peripheral nervous system system distributed from the central nervous system to various part of the body constitutes the peripheral nervous system. Each ganglion give of literally 8 to 10 nerves which innovate  prostomium and buccal chamber. Nerves from peripheral connective supply the peristomium and the local chamber while from sub pharyngeal ganglia supply structures in the second third and fourth segment is segmental ganglion of ventral nerve cord give of three pair lateral nerve which innovate their respective segments.

The Nova of the mixed type consisting of both afferent or sensory fibre and efferent or motor fiber.


3 autonomic nervous system it consists of sensitive nerve spread beneath the epidermis and on the alimentary canal and connected with the Peri pharyngeal connective. All the activities of earthworm control of Nerves system. The nerve consists of both afferent and and motor nerve fibre. The former start from sensory cells a receptor organ in the epidermis and terminate in the ventral nerve cord in fine branches. Near the branches in the cord and forming a synapse with them arise similar branches of of the motor knob fibre which Run outward and terminate in the muscle these circuits form of reflex arc along wheat the nerve impulse are terminate. The stimuli or since in poles are connected from the the receptor bye the afferent fibre The ventral nerve cord, from where they are reflected back as motor in pulses along motor nerve fibre to the muscles which contract. And adjuster neurone mein be present between the Sen sorry and motor neurone through which and impulse may be visited two opposite side of the same segment or another or several segments thus bringing about coordination of activities of different parts of body   




Comments

Post a Comment

Popular posts from this blog

Rana tigrina (frog)

Image
  Phylum: Chordata                              frog( rana tigrina) Sub Phylum: Vertebrata Group: Gnathostomata Class: Amphibia Order: Anura Genus:  Rana Species :  tigrina Common Name: Frog   Habit and Habitat : Frog is an amphibian animal, it can live both in water and land. Its tadpole larva is completely aquatic in habitat. Later metamorphos into adult, the characters of larva are completely disappearing in the adult. On the land frog locomotes by jumping movement and in the water swims actively due to webbed foot. It is completely solitary and free living animal but during rainy season always live in colony. The body skin is always in moist condition. Therefore easily respire by cutaneous respiration. Nutritionally larva is herbivorous and adult is carnivorous or insectivorous. During breeding season usually at night, frogs gather nearby the pond or shallow water. In the group, there are more males than the female, only the males produces high pitch croaking sound to attract femal
Read more

Digestive system in earthworm

Image
             Habit and Habitat: Earthworm is a burrowing animal usually live inside the soil surface in solitary. It burrows by ingesting soil from the mouth and liberate out from the anus on the soil surface as castings.  # It feeds upon the dry or green leaves, dead materials, insect larvae, eggs, etc. # Usually earthworm is widely distributed in fertile or loam soil which burrow at the depth of about 6″ inches. # During dry season. It can grow at the depth pf 1m but during rainy season, found on the soil surface. # Earthworm is commonly called friend of farmer or natural plough. # the distribution of earthworm is almost cosmopolitan found from the sea level up to the altitude of 3000m. BODY STRUCTURE: 1. Long, cylindrical, almost pointed at the both ends, metamerically segmented. 2. Number of segment varies between 100-120, each segment is also called somite or metamere and divisible into dorsal, ventral, anterior and posterior regions. 3. Dorsal portion is dark in colour due to dep
Read more

REPRODUCATION IN EARTHWORM

                                                              Reproductive system in earthworm Earthworms  are hermaphrodites, and  reproduction  mostly occurs through cross-fertilization by copulation. ... The  earthworms  lie in contact with each other in the opposite direction, such that, the male  genital  apertures of one  earthworm  is near to the spermathecal pores of the other  earthworm male reproductive system Organs a) testes b) testis sac c) seminal vesicle d)  vasa deferentia e) prostate gland f) accessory gland TESTES Testes are very minute structures that are whitish in colour. There are two pairs of testes and they are lobed. One pair each is present in segment 10 th  and 11 th  that are found attached with the posterior surface of 9/10 and 10/11 inter-segmental septa. Each testis possess 4-8 finger like lobules that contains rounded cells in masses termed as spermatogonia. Testes are enclosed within testis sac. During the young stage of the earthworm, the testes are fu
Read more