The alimentary canal starts from mouth and it consists of the preoral cavity, pharynx, oesophagus, crop and gizzard forming the foregut or stomodaeum; the mesenteron forming the midgut and the ileum, colon and rectum constituting the hindgut or proctodaeum. The stomodaeum and proctodaeum are ectodermal in origin and lined internally by the continuation of the exoskeletal cuticle, while the mesenteron is endodermal in origin and without cuticular lining.

1. Shri Shivaji Education Society, Amravati's
Shri Pundlik Maharaj Mahavidyalaya, Nandura Rly. Dist. Buldana
Topic: Digestive System of Cockroach
Class: B.Sc-I, Sem-I
Shantaram Bhoye
Assistant Professor & Head
Department of Zoology
M.Sc., NET-JRF, SET, M.A.(Eng.)

2. Mr. Shantaram Bhoye, Assistant Professor, Shri Pundlik Maharaj Mahavidyalaya, Nandura Rly., Dist. Buldana
Digestive System of Cockroach:
 The digestive system of cockroach consists of the alimentary canal and digestive glands.
Alimentary Canal of Cockroach:
 The alimentary canal starts from mouth and it consists of the preoral cavity, pharynx,
oesophagus, crop and gizzard forming the foregut or stomodaeum;
 The mesenteron forming the midgut and the ileum, colon and rectum constituting the hindgut
or proctodaeum.

3. Mr. Shantaram Bhoye, Assistant Professor, Shri Pundlik Maharaj Mahavidyalaya, Nandura Rly., Dist. Buldana
Foregut:
 The mouth opens behind into a short tubular pharynx which passes vertically upwards, then it bends
backward into an oesophagus.
 The oesophagus is a narrow tubular passage which passes through the neck and gradually expands in
the thorax, finally taking the shape of sac-like structure in abdomen.
 This sac-like structure is called crop which is thin-walled and muscular.
 The crop is followed by a gizzard or pro-ventriculus.
 The gizzard is a round, thick-walled bulb-like structure.
 Structurally, it has an outer thick layer of circular muscles and its lumen gets considerably reduced
due to the in-folding of its wall.
 The gizzard can be divided into anterior armarium and posterior stomodaeal valve.
 The cuticular lining of armarium is thickened to form six highly chitinised plates called teeth.
 The deep grooves are also provided with fine bristles.

4.  The teeth help in grinding the food,
while bristles help in straining the food
to allow only well crushed food to pass
on.
 The hind part of the gizzard projects
into the midgut as a funnel, called
stomodaeal valve which prevents the
passage of food from midgut into the
gizzard.
Mr. Shantaram Bhoye, Assistant Professor, Shri Pundlik Maharaj Mahavidyalaya, Nandura Rly., Dist. Buldana

5. Midgut:
 The gizzard is followed by a narrow tube of uniform diameter representing the midgut or
mesenteron.
 Its junctional region with the gizzard, arise eight finger-like tubular blind processes called
hepatic caeca or enteric caeca or mesenteric caeca.
 The internal lining of the midgut is several folds forming villi and covered by a very thin
layer of transparent peritrophic membrane.
 The peritrophic membrane is secreted by the anterior end of the cardia and it is permeable for
enzymes and for the end products of digestion.
 It also protects the wall of the midgut.
 The process of digestion is completed in this region of the alimentary canal and the digested
food is also absorbed in it.
Mr. Shantaram Bhoye, Assistant Professor, Shri Pundlik Maharaj Mahavidyalaya, Nandura Rly., Dist. Buldana

6. Mr. Shantaram Bhoye, Assistant Professor, Shri Pundlik Maharaj Mahavidyalaya, Nandura Rly., Dist. Buldana

7. Hindgut:
 The junction of midgut and hindgut is marked by the presence of nearly sixty to one hundred
fifty long, filamentous and blind Malpighian tubules which are not related with digestion but
with excretion.
 The hindgut is relatively broader than the midgut.
 It is ectodermal and lined internally with the cuticle.
 Its anterior region following the midgut is called ileum which is followed by a long and
coiled colon.
 The colon ends in a broad rectum which opens by an anus lying posteriorly below the 10th
tergum.
 The rectal papillae is very thin but this is adaptive device for absorbing maximum water from
the passing out faeces.
Mr. Shantaram Bhoye, Assistant Professor, Shri Pundlik Maharaj Mahavidyalaya, Nandura Rly., Dist. Buldana

8. Digestive Glands:
 Digestive glands of cockroach generally include the salivary glands, the glandular cells of
the midgut and hepatic caeca.
Salivary Glands:
 A pair of salivary glands, one on either side of the crop in the thorax, are found associated
with the alimentary canal.
 Each gland has two glandular portions and a bag-like diverticulum or receptacle or reservoir
in which saliva is stored.
 From the glandular portions of the two sides arise salivary ducts which unite to form a
common duct.
 Likewise, two ducts from the reservoirs also join to form another common duct.
 The glandular cells of the internal lining of the midgut and hepatic caeca also produce juice
containing digestive enzymes.
Mr. Shantaram Bhoye, Assistant Professor, Shri Pundlik Maharaj Mahavidyalaya, Nandura Rly., Dist. Buldana

9. Mr. Shantaram Bhoye, Assistant Professor, Shri Pundlik Maharaj Mahavidyalaya, Nandura Rly., Dist. Buldana

10. Food and feeding of Cockroach:
 Cockroach is omnivorous; it feeds on every type of animal and plant materials, though it
prefers to feed on sugary and starchy substances but tastes almost everything it comes
across.
 The presence of food is detected by the sensory receptors present on the antennae and
maxillary palps.
 The maxillae pick up and bring food to the mandibles for mastication.
 During the act of mastication the teeth of the mandibles bite and chew the food.
 The labrum and labium work like lips to prevent the loss of food from the mandibles at the
time of mastication.
 The chewed food is pushed into the pre-oral cavity by maxillae, prostheca of mandibles and
labium from where it is swallowed into the mouth.
Mr. Shantaram Bhoye, Assistant Professor, Shri Pundlik Maharaj Mahavidyalaya, Nandura Rly., Dist. Buldana

11. Physiology of Digestion:
 Salivary glands open by their common duct in the pre-oral cavity at the base of the hypo
pharynx, hence, saliva mixes with the food during mastication.
 The saliva contains enzymes like amylase, chitinase and cellulase which hydrolyse
different carbohydrates; some of them are converted into glucose.
 The saliva also moistens the food for its easy transport in the alimentary canal.
 However, such food is swallowed by the mouth and transported through the pharynx and
oesophagus into the crop.
 After reaching into the crop, the digested carbohydrate in the form of glucose is absorbed
and remaining food comes across the secretion of the glandular cells of the midgut.
Mr. Shantaram Bhoye, Assistant Professor, Shri Pundlik Maharaj Mahavidyalaya, Nandura Rly., Dist. Buldana

12.  Actually, the digestive juice secreted by the glandular cells of the midgut.
 This juice contains amylolytic enzymes like invertase, maltase and lactase to complete the
carbohydrate digestion; proteolytic enzymes like trypsin, proteases and peptidases to digest
proteins into amino acids; lipolytic enzymes for the digestion of fats into fatty acids and
glycerine.
 Thus, maximum digestion occurs in crop and then the food descends down through the gizzard
into the midgut.
 The gizzard grinds and crushes the food particles into finer ones and again it filters the food
with the help of the fine bristles present at its posterior region.
 Thus, food coming into the midgut is very fine paste-like. The stomodaeal valves check the
backward passage of food from the midgut into the crop.
Mr. Shantaram Bhoye, Assistant Professor, Shri Pundlik Maharaj Mahavidyalaya, Nandura Rly., Dist. Buldana

13. Mr. Shantaram Bhoye, Assistant Professor, Shri Pundlik Maharaj Mahavidyalaya, Nandura Rly., Dist. Buldana
Absorption:
The end products of digestion, i.e., proteins as amino acids, fats as fatty acids and glycerine and
carbohydrates as glucose are absorbed by the lining cells of the midgut and hepatic caecae and
transported to the different parts of the body for their use.
The excess food material is stored in the fat body as glycogen, fat and probably albumen.
Egestion:
The undigested food passes into the hindgut. In the rectum, maximum of water is absorbed from it,
hence, the undigested residue which remains here is almost solid.
This is egested out in the form of small dry pellets through the anus.