Welcome to Elearnin, In this 3d animated videos we will tech you about the Morphology and Anatomy of an Earthworm from the Class 11 Biology - CBSE – NCERT by Elearnin

In this video you will learn about Earthworm - Morphology
1:14c Earthworm – Megascolex
Types of Earthworms
1:14 Pheretima Posthuma – Anatomy
2:44 Earthworm Reproductive system
3:58 Fertilization of Earthworm
4:20 Earthworm egg formation, Copulation
4:54 Economic Significance
#EarthwormMorphology #EarthwormAnatomy #Biology #CBSE #3dAnimation #Education #Anatomy

0:12 Earthworm - Megascolex
It has a circular body made up of segments. It is the first category to have blood circulation. It has eight pairs of lateral hearts. Their have setae for movement. In order to fecilitate respiration through the skin, it is moist at all times. Earthworms are bilingous creatures. They usually undergo sexual reproduction. In bisexual organisms, embryonic development is direct. In unisexual organisms, it is indirect. Earthworms are considered as friends to the farmers. The main types of earthworms found in India are Pheretima, Lumbricus and Megascolex. Now, let us learn about Pheretima.


1:14 Pheretima Posthuma:

It has a long cylindrical body divided into over 100 to 120 segments. The dorsal surface of the body is marked by a dark median mid dorsal linealong the longitudinal axis of the body. The upper ventral surface of the body contains genital pores. The promostium covers it’s mouth at the anterior end. It has a few sensors. The promostium is the first segment of the body. In a mature worm, segments 14-16 are covered by a prominent dark band of glandular tissue called clitellum or cingulum. The body is divisible into three prominent regions –preclitellar, clitellar and postclitellar segments. Four pairs of spermathecal apertures are situated on the ventro-lateral sides of the intersegmental grooves, i.e., 5th -9th segments. A single female genital pore is present in the mid-ventral line of 14th segment. A pair of male genital pores are present on the 18th segment. Except the clitellar segments, all other segments contain a S – shaped chitinous setae in the epidermal pits. Setae can be extended or retracted. Their principal role is in locomotion.


2:44 Reproductive System:
An earthworm is a bisexual creature. There are two pairs of testes present in the 10th and 11th segments. Their vasa deferentia run up to the 18th segment where they join the prostatic duct. They have two pairs of vasa differentia in the 11th and 12th segments. One pair of ovaries is attached at the inter-segmental septum of the 12th and 13th segments. Ova convert to sprem. Vasa deferentia opens to the exterior by a pair of male genital pores on the ventro-lateral side of the 18th segment. Two pairs of accessory glands are present one pair each in the 17th and 19th segments. Four pairs of Spermathecae are present on the 6th to 9th segments. They receive and store spermatozoa during copulation. Ovarian funnels are present beneath the ovaries which continue into oviduct, join together and open on the ventral side as a single median female genital pore on the 14th segment.


3:58 Fertilization:
A mutual exchange of sperm occurs between two worms during mating. One worm has to find another worm and they mate juxtaposing opposite gonadal openings exchanging packets of sperms called spermatophores.

4:20 Egg Formation and Copulation:
Mature sperm and egg cells and nutritive fluid are deposited in cocoons produced by the gland cells of clitellum. Fertilisation and development occur within the cocoons which are deposited in soil. Such cacoons are deposited in the soil. The cocoon holds developing embryos. After about 3 weeks, each cocoon produces an average of four. Development of earthworms is direct, i.e., there is no larva formed.

4:54 Economic Significance:
Earthworms are known as ‘friends of farmers’ because they make burrows in the soil and make it porous which helps in respiration. The process of increasing fertility of soil by the earthworms is called vermicomposting. Their excreta fertilizes the soil. They are also used as bait in game fishing.


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