10Cockroach

πŸ“š
COCKROACH
β–’ Identity:
❖ Scientific Name: Periplaneta americana
❖ Common Names:
  • β€’
    Bombay canary
  • β€’
    American cockroach
  • β€’
    Ship cockroach
❖ Distribution: Cosmopolitan
❖ Habitat: Dark and damp places
❖ Habit: Nocturnal, omnivorous, scavenger, cannibalistic and coprophagous
❖ Colour: Dark brown
β–’ Body Division:
❖ Body Form: Elongated, dorsoventrally flattened, bilaterally symmetrical and segmented
❖ Main Regions: Head, thorax and abdomen

Table 1: Body Segments

Region
Young
Adult
Head
6 segments
6 segments
Thorax
3 segments
3 segments
Abdomen
11 segments
10 segments
Total
20 segments
19 segments
β–’ Head:
❖ Position: Mobile due to flexible neck
❖ Orientation: Hypognathous; mouth parts directed downward
❖ Head Capsule: Formed by fusion of 6 segments
❖ Head Sclerites:
  • β€’
    Epicranial plates
  • β€’
    Frons
  • β€’
    Clypeus
  • β€’
    Labrum
  • β€’
    Genae
  • β€’
    Occiput
❖ Endoskeleton: Tentorium; forms apodemes for muscle attachment
❖ Head Bears:
  • β€’
    One pair compound eyes
  • β€’
    One pair antennae
  • β€’
    Mouth parts
β–’ Compound Eye:
❖ Eye Type: Compound eye
❖ Unit: Ommatidium
❖ Number: About 2000 ommatidia per compound eye
❖ Vision: Mosaic vision
❖ Nocturnal Vision: Superposition image; useful in dim light
β–’ Antenna:
❖ Number: One pair
❖ Origin: Antennary socket
❖ Parts:
  • β€’
    Scape
  • β€’
    Pedicel
  • β€’
    Flagellum
❖ Function: Tactile and olfactory sense
❖ Important Organ: Johnston's organ in pedicel
β–’ Mouth Parts:
❖ Type: Biting and chewing / mandibulate type
❖ Preoral Cavity: Cavity in front of mouth parts

Table 1: Mouth Parts of Cockroach

Mouth Part
Function / Feature
Labrum
Upper lip; covers preoral cavity
Mandibles
One pair; cutting and grinding food
Maxillae
One pair; hold, taste and manipulate food
Labium
Lower lip; formed by fusion of second maxillae
Hypopharynx
Tongue-like; common salivary duct opens at its base
❖ Maxilla: Consists of cardo, stipes, galea, lacinia and 5-jointed maxillary palp
❖ Labium: Consists of postmentum, prementum, glossae and paraglossae
β–’ Thorax:
❖ Segments:
  1. Prothorax
  2. Mesothorax
  3. Metathorax
❖ Each Segment Has:
  • β€’
    Dorsal tergum / notum
  • β€’
    Ventral sternum
  • β€’
    Lateral pleura
❖ Wings:
β—‰ Pairs: Two pairs
β—‰ Forewings: First pair; leathery; tegmina / elytra / wing covers
β—‰ Hindwings: Second pair; thin, transparent and membranous
β–’ Legs:
❖ Number: Three pairs
❖ Names:
  • β€’
    Prolegs
  • β€’
    Mesolegs
  • β€’
    Metalegs
❖ Origin: Each thoracic segment bears one pair of legs

Table 1: Parts of Cockroach Leg

Part
Feature
Coxa
Basal swollen part
Trochanter
Smallest part
Femur
Large segment
Tibia
Long segment
Tarsus
Made of 5 tarsomeres
Pretarsus
Contains claws and arolium
❖ Adhesive Structures: Pulvilli / plantulae and arolium help in attachment
β–’ Abdomen:
❖ Segments: 11 in embryo, 10 in adult
❖ Male Abdomen: All nine sterna visible
❖ Female Abdomen: Only seven sterna visible; 7th sternum forms brood pouch / oothecal chamber
❖ Anal Cerci: One pair; present in both sexes; sensory
❖ Anal Styles: One pair; present only in male on 9th sternum
❖ Stink Glands: Repugnatorial glands between 5th and 6th terga
❖ Anus: Opens below 10th tergum
β–’ Body Wall:
❖ Layers:
  1. Cuticle
  2. Epidermis
  3. Basement membrane
❖ Cuticle: Secreted by epidermis; forms exoskeleton
❖ Cuticle Layers:
  • β€’
    Epicuticle
  • β€’
    Exocuticle
  • β€’
    Endocuticle
❖ Chitin: Present mainly in exocuticle and endocuticle
❖ Epicuticle: Outer thin waxy layer; prevents water loss
❖ Ecdysis: Shedding of cuticle during growth
β–’ Body Cavity:
❖ Main Cavity: Haemocoel
❖ Fluid: Haemolymph
❖ True Coelom: Reduced; mainly around gonads
❖ Sinuses:
  • β€’
    Pericardial sinus
  • β€’
    Perivisceral sinus
  • β€’
    Perineural sinus
β–’ Digestive System:
❖ Type: Complete alimentary canal
❖ Regions: Foregut, midgut and hindgut
❖ Foregut: Ectodermal and cuticle-lined
❖ Foregut Parts:
  • β€’
    Preoral cavity
  • β€’
    Mouth
  • β€’
    Buccal cavity
  • β€’
    Pharynx
  • β€’
    Oesophagus
  • β€’
    Crop
  • β€’
    Gizzard
❖ Crop: Large thin-walled sac for food storage
❖ Gizzard: Chitinized muscular organ with 6 teeth; grinds and filters food
❖ Midgut: Endodermal, non-cuticular; digestion and absorption
❖ Hepatic Caeca: 6–8 caeca at anterior midgut; secrete digestive enzymes
❖ Peritrophic Membrane: Secreted by midgut; protects midgut from abrasion and enzyme action
❖ Hindgut: Ectodermal and cuticle-lined
❖ Hindgut Parts:
  • β€’
    Ileum
  • β€’
    Colon
  • β€’
    Rectum
❖ Rectal Papillae: Six; absorb water, salts and minerals
β–’ Salivary Glands:
❖ Number: One pair
❖ Location: Extends from hypopharynx to crop
❖ Parts: Principal salivary glands and salivary receptacles
❖ Opening: Common salivary duct opens at base of hypopharynx
β–’ Circulatory System:
❖ Type: Open / lacunar circulatory system
❖ Blood: Haemolymph
❖ Respiratory Pigment: Absent
❖ Blood Function: No major role in oxygen transport
❖ Heart: Dorsal tubular contractile heart
❖ Heart Chambers: 13 chambers; 3 thoracic and 10 abdominal
❖ Ostia: Lateral openings in heart chambers
❖ Alary Muscles: 12 pairs; fan-shaped; attached to dorsal diaphragm
❖ Blood Flow: Posterior to anterior
β–’ Respiratory System:
❖ Type: Tracheal system
❖ Main Organs: Tracheae, tracheoles and spiracles
❖ Spiracles: 10 pairs; 2 thoracic and 8 abdominal
❖ Largest Spiracle: First pair of thoracic spiracles
❖ Tracheae: Chitin-lined air tubes with taenidia
❖ Air Sacs: Dilated tracheae without taenidia; reduce body weight and store air
❖ Inspiration: Mostly passive
❖ Expiration: Active process
β–’ Excretory System:
❖ Excretory Type: Uricotelic
❖ Major Waste: Uric acid
❖ Main Excretory Organ: Malpighian tubules
❖ Malpighian Tubules: 90–150 yellow unbranched tubules at junction of midgut and hindgut
❖ Other Excretory Structures:
  • β€’
    Fat bodies
  • β€’
    Nephrocytes
  • β€’
    Uricose glands
  • β€’
    Cuticle
❖ Fat Body Cells:

Table 1: Fat Body Cells

Cell Type
Function
Trophocytes
Store food substances
Mycetocytes
Contain symbiotic microorganisms
Oenocytes
Form intermediary substances during ecdysis
Urate cells
Store uric acid
β–’ Nervous System:
❖ Types:
  • β€’
    Central nervous system
  • β€’
    Peripheral nervous system
  • β€’
    Sympathetic nervous system
❖ Brain: Supra-oesophageal ganglion
❖ Sub-oesophageal Ganglion: Formed by fusion of ganglia below oesophagus
❖ Nerve Cord: Double, solid and ventral
❖ Segmental Ganglia: 9 ganglia; 3 thoracic and 6 abdominal
❖ Peripheral Nerves: Arise from CNS ganglia
❖ Sympathetic System: Stomatogastric and caudal nervous system
β–’ Endocrine System:
❖ Neurohaemal System: Well developed

Table 1: Endocrine Structures

Structure
Function
Intercerebral gland
Secretes brain hormone
Prothoracic gland
Secretes ecdysone hormone for moulting
Corpora allata
Secretes juvenile hormone; regulates metamorphosis
Corpora cardiaca
Stores and releases neurohormones
β–’ Sense Organs:

Table 1: Sense Organs

Sense
Organs
Touch
Antennae, maxillary and labial palps
Taste
Maxillary palps, labium, mouth wall and pharynx
Smell
Antennae
Hearing / vibration
Anal cerci and special receptors
Vision
Simple eyes and compound eyes
β–’ Male Reproductive System:
❖ Testes: One pair; trilobed; present around 3rd–6th abdominal segments
❖ Vasa Deferentia: One pair; carry sperm from testes
❖ Mushroom Gland: Accessory gland; forms inner layer of spermatophore
❖ Ejaculatory Duct: Common duct opening through male gonopore
❖ Phallic Gland: Conglobate gland; forms outer layer of spermatophore
❖ Phallomeres: Chitinous asymmetrical structures around male genital pore
❖ Main Role: Spermatophore formation and copulation
β–’ Female Reproductive System:
❖ Ovaries: One pair; present around 2nd–6th abdominal segments
❖ Ovarioles: Each ovary has 8 ovarioles; total 16 ovarioles
❖ Oviducts: Oviducts unite to form common oviduct
❖ Vagina: Common oviduct opens into genital chamber
❖ Spermatheca: Stores sperm
❖ Collateral Glands: Secrete oothecal covering
❖ Genital Pouch: Contains gonopore, spermathecal opening and collateral gland openings
❖ Ootheca: Egg case containing 16 fertilized eggs arranged in 2 rows of 8 each
β–’ Development:
❖ Fertilization: Internal
❖ Egg Case: Ootheca
❖ Young Stage: Nymph
❖ Nymph: Resembles adult but smaller and wingless
❖ Metamorphosis: Incomplete / paurometabolous
❖ Moulting: Occurs 10–13 times
❖ Adult Formation: Adult cockroach develops after repeated moulting
β–’ High-Yield Points:

Table 1: Must Remember

Question Clue
Answer
Scientific name
Periplaneta americana
Mouth parts
Biting and chewing
Body cavity
Haemocoel
Circulation
Open / lacunar
Respiration
Tracheal system
Number of spiracles
10 pairs
Heart chambers
13
Excretory organ
Malpighian tubules
Excretory product
Uric acid
Vision
Mosaic vision
Larval stage
Nymph
Metamorphosis
Incomplete / paurometabolous
Egg case
Ootheca
Ootheca eggs
16 eggs in 2 rows of 8
Male-only structure
Anal styles
Both sexes
Anal cerci
Q1.
The scientific name of cockroach is
Q2.
Cockroach is commonly called
Q3.
The body of cockroach is divided into
Q4.
The mouth parts of cockroach are
Q5.
The head of cockroach is described as hypognathous because
Q6.
The exoskeleton of cockroach is mainly made of
Q7.
Periodic shedding of cuticle in cockroach is called
Q8.
The body cavity of cockroach is
Q9.
Blood of cockroach is called
Q10.
Circulatory system of cockroach is
Q11.
The heart of cockroach is
Q12.
Number of heart chambers in cockroach is
Q13.
Respiration in cockroach occurs through
Q14.
Number of spiracles in cockroach is
Q15.
Tracheae of cockroach are prevented from collapsing by
Q16.
The main excretory organs of cockroach are
Q17.
Cockroach is mainly
Q18.
Malpighian tubules in cockroach are present at the junction of
Q19.
The food storage organ in cockroach is
Q20.
The gizzard of cockroach mainly helps in
Q21.
Hepatic caeca in cockroach are present in
Q22.
Rectal papillae of cockroach help in
Q23.
Compound eye of cockroach is made up of many units called
Q24.
Vision in cockroach is mainly
Q25.
The antennae of cockroach mainly function as
Q26.
The first pair of wings of cockroach is called
Q27.
The second pair of wings in cockroach is
Q28.
The pretarsus of cockroach leg bears
Q29.
Anal cerci in cockroach are present in
Q30.
Anal styles in cockroach are present in
Q31.
The egg case of cockroach is called
Q32.
One ootheca of cockroach usually contains
Q33.
The young one of cockroach is called
Q34.
Metamorphosis in cockroach is
Q35.
The female reproductive system of cockroach has total
Q36.
Collateral glands of female cockroach secrete
Q37.
Mushroom gland in male cockroach helps in
Q38.
The nervous system of cockroach consists of
Q39.
The endocrine gland secreting ecdysone in young cockroach is
Q40.
Juvenile hormone in cockroach is secreted by