Excretion in Invertibrate,(Excretion in Planaria, Excretion in Earthworm,Excretion in Cockroach)

Excretion in Invertibrate

Excretion in Planaria

 Excretion in invertibrate

Planaria is a fresh water invertebrate.

 Excretory product:
planaria remove ammonia and it is ammonotlic. This excretion occurs by two methods, diffusion, specialized excretory system.

Excretory organs:
Planaria has simple tubular excretory system called protonephiridia. Protonephridia arranged in two longitudinal trunk one on each side of the body. Each track consists of a network of tubules without internal openings. These tubules divide into small branches which open in flame cells.
Tubules open on the outside by small opening called nephridiophores.

Structure of flame cell:
Flame cells are club shaped hollow cells. Each flame cell contains nucleus, cytoplasm and internal cavity.
Group of cilia is present in the cavity. Cilia perform a movement like a flame of candle. Flame cells also has many cytoplasmic elongations.

Mechanism of excretion:
Flame cells absorb wastes and push them into the cavity. From cavity the cilia carried the wastes to the excretory tubules. Finally,the wastes are excreted to the upside by nephridiophore.

2. Excretion in Earthworm:

Earthworm live in moist soil.

Excretory product:
These are CO2, ammonia, urea.

Excretory organs:
In earthworm excretory system consists of tubes called nephridia. Nephridia is present in all segments without first three and last segment. Each segment contains a pair of nephridia. Nephridia is opened at both sides.
Structure of Nephridium:
Each nephridium consists of three parts:
1 Nephrostome
2 Main body
3 Nephridiopore
Nephrostomes: It is rounded and ciliated funnel. It open into the coelomic cavity and collect coelomic fluid.

Main body : It consists of following two parts:
Coiled Tubular part: Nephrostome opens into this part. Blood capillaries surround these coiled tubes. Bladder: The coiled tubular part open into a side part called bladder.
Nephridiopre: The bladder opens outside by a small pore called nephridiopore.

Mechanism of Excretion:
Nephrostome collects wastes from coelomic fluid and transfer it into the main body. When fluid moves along the coiled tubules, its cells reabsorb important substances from it. After reabsorption only urine is left in the tubule. From tubule urine is pushed into bladder. Finally urine is excreted out by nephridiopore.

3. Excretion in  Cockroach

Cockroach is a terrestrial animal. It has acute shortage of water.

Excretory Products:
In cockroach excretory product is uric acid. Cockroach excretes uric acid without losing water.

Excretory organ:
Excretory organ of cockroach is malpighian tubules.

Malpighian tubules are located at the junction of mid gut and hind gut. Malpighian tubules are the only removal organs in the animal kingdom that are connected with digestive tract. So, excretory waste and digestive waste are removed together.

Number: These are six groups of malpighian tubules in a cockroach. Each group consists of about 15-20 malpighian tubules.

Color: They are yellowish.

Shape: They are thread like or hairs like unbranched tubes.

Each malpighain tubule is blind and an inch long.  A malpighian tubule consists of three parts:
Proximal end: This end opens into the hind gut.
Lumen or duct: This is the middle part. Distal end: This end is blind or closed.

Mechanism of Excretion:
Distal end float freely in the haemolymph (body fluid). It collects nitrogenous waste and push them into the hind gut. Hind gut reabsorb water and push the waste into the rectum. A rectum reabsorbs large amount of water and salt. Thus,uric acid become dry and excreted out with the feces without losing water


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