Classification of Cockroach:

  • Kingdom           Animalia
  • Phylum             Arthropoda
  • Class                   Insecta
  • Superorder         Dictyoptera
  • Order                   Blattodea

Facts about Cockroaches:

  • The cockroaches are one of the ancient insects and they originate about280 Million years ago.
  • A cockroach can face any environment and can live in extreme conditions.
  • A cockroach can swim up to 40-50 mins in water.
  • The cockroach is fast moving insect and can walk up to 3 miles per hour
  • A cockroach can live without water and food up to a month.
  • If we cut the head of the cockroach he can live for a week or more.
  • World’s largest cockroach is 6 inches long.

 

 

 

CIRCULATORY SYSTEM IN COCKROACH:

 

The circulatory system in a cockroach is open type without blood vessels and blood flows in spaces called “sinuses” in
the body cavity.

WHAT IS AN OPEN CIRCULATORY SYSTEM?

 

The open circulatory system is the system where blood rather than being sealed tight in arteries and veins, diffuses the body.

Parts of cockroach circulatory system:

The circulatory system in cockroach consists of

  • Blood
  • Heart
  • Sinuses
  • Alary muscles

 

BLOOD:

Blood is just a fluid called Hemolymph. It performs the functions of blood, lymph and intestinal fluid which are otherwise three different highly specialized fluids in animals with the closed circulatory system.

It is a clear fluid plasma in which are suspended nucleated cells or haemocytes. This plasma consists of various ions like sodium, potassium, calcium; organic compounds like citrate; amino acids alanine, cysteine, glycine, tyrosine, valine etc.

It is white in colour due to the absence of respiratory pigments “haemoglobin” so it does not help in the transport of respiratory gases but it transports all the nutrients to all the organs of the body. It also collects waste material from organs
and supplies it to excretory organs called “Malphigian
tubules”

 HAEMOCYTES:

Hemocytes are the blood cells of cockroach which are nucleated mostly.

Types of hemocytes:

  1. Prohaemocytes
  2. Plasmocytes
  3. Granulocytes
  4. Cystocytes/ Granulocytes

 

 SINUSES:

The body cavity of cockroaches called sinuses. The body cavity of cock­roach is not a true coelom but a haemocoel containing blood (haemolymph).

 

Division of sinuses:

The body cavity of cockroach is divided into three chambers or sinuses.

  • Pericardial sinuses
  • Perivisceral sinuses
  • Perineural sinuses

 

 Pericardial sinuses:

The dorsal sinus is also called the pericardial sinus. The heart is present in the “pericardial sinus”

 Periviceral Sinuses:

The middle sinus consist of visceral organs hence is called as “perivisceral sinus”

 Perineural Sinuses:

The ventral sinus surrounds the ventral nerve cord hence it is called as “perineal sinus”

 HEART:

It is present in pericardial sinus and consists of 13
chambers
. Blood flows from posterior chamber to the preceding chamber that means from 13th to 12th, from 12th to 11th and so on.

 Ostia:

They have lateral pores which open into pericardial sinus as “Ostia”

The first chamber opens into head sinus
through an aorta. Perivisceral sinus collects the blood from head sinus.

 ALARY MUSCLES:

These are triangular shaped muscles and contraction and relaxation of these muscles are responsible for forcing the blood into the heart.

 CIRCULATION:

When the alary muscles contract, the blood flows from the body cavity that is the perivisceral and perineural sinuses into a pericardial sinus.

When alary muscles relax, blood flows from the pericardial sinus into the heart through pores called ostia.  Peristaltic
contractions of the heart move the blood from posterior chambers to the anterior chamber. From the first chamber of the heart, blood moves through an aorta into the head sinus. From the head sinus, the blood flows into the body cavity that is the perivisceral and perineural sinuses. From here it goes to pericardial sinus and the cycle is repeated. Heartbeats
at the rate of 100-200 per minute at 270C. A complete cycle of circulation of haemoglobin through the body takes 20-30 minutes.

 

Open circulatory system of cockroach
Open circulatory system of cockroach

The open circulatory system of the cockroach

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