notes for students

  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

                                                              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

             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

  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