Biology · Structural Organisation in Animals · NEET
The cockroach is a sexually distinct (dioecious) animal. The MALE has a pair of testes, a seminal vesicle that stores sperm as bundles called spermatophores, and a mushroom-shaped gland for secretions. The FEMALE has two ovaries (each with 8 ovarioles = 16 total), a spermatheca to receive sperm, and collaterial glands that make the egg-case (ootheca). The NERVOUS system is NOT centred in the head: the brain (supra-oesophageal ganglion) controls only a little, and most control comes from a chain of paired ganglia on a double VENTRAL nerve cord. Memory hook: "Sperm Stored in Seminal vesicle; brain is small, nerve cord runs BELOW (ventral)."
Cockroach male system (testis to seminal vesicle storing spermatophores, plus mushroom gland) and female system (ovaries with 16 ovarioles, spermatheca, ootheca-making collaterial glands), with the spread-out nervous system: a small brain and a double ventral nerve cord bearing paired segmental ganglia, which lets a headless cockroach live for days.
Your doubts, answered
Where exactly are sperms stored in a male cockroach - seminal vesicle or mushroom gland?
Sperms are stored in the SEMINAL VESICLE, not the mushroom gland. In the male, a pair of testes lies in the 4th to 6th abdominal segments. From each testis a thin vas deferens carries sperm to the seminal vesicle, where sperms are stored and packed into bundles called spermatophores. The mushroom-shaped gland (utricular gland) at the 6th to 7th segments is only an ACCESSORY gland that adds secretions; it does not store sperm. NEET has directly asked this (2016).
How many ovarioles does a female cockroach have?
A female cockroach has two ovaries, and each ovary is made of 8 ovarioles, so there are 16 ovarioles in total. The ovaries lie in the 2nd to 6th abdominal segments. NCERT states 8 per ovary; a common trap option says 16 per ovary, which is wrong. Remember: 8 each side, 16 in all.
Why can a cockroach live for several days after its head is cut off?
Because the cockroach nervous system is spread through the body, not packed in the head. The brain (supra-oesophageal ganglion) in the head controls only a SMALL part of nervous activity. Most control comes from a chain of paired ganglia connected by a double VENTRAL nerve cord running along the lower (ventral) side of the body. These ganglia can control local body parts on their own, so a headless cockroach keeps moving for days until it dies from being unable to drink water. This is the NEET 2020 question.
Is the cockroach nerve cord on the top (dorsal) or bottom (ventral) side?
It is VENTRAL - it runs along the lower side of the body. This is the opposite of vertebrates like the frog, whose spinal (nerve) cord is dorsal (on the back). NTA often swaps 'ventral' with 'dorsal' in options to test this. Cockroach = double, solid, ventral nerve cord.
What is the difference between a spermatophore and an ootheca?
A spermatophore is a bundle of sperms formed in the MALE (packaged in the seminal vesicle) and transferred to the female during mating. An ootheca is the hard egg-case made in the FEMALE by the collaterial glands, containing 14 to 16 fertilised eggs. Simple rule: spermatophore = sperm packet (male); ootheca = egg case (female).
What do the collaterial glands do in a female cockroach?
The two collaterial glands in the female produce the secretion that hardens around the eggs to form the protective egg-case, the ootheca. They are reproductive (not excretory) glands. Do not confuse them with Malpighian tubules, which handle excretion.
⚠️ The NEET trap ✗ The cockroach brain controls the whole body, and its main nerve cord lies on the dorsal (upper) side like in vertebrates. ✓ The cockroach brain (supra-oesophageal ganglion) controls only a small part; most control is by segmental ganglia on a double VENTRAL nerve cord. That is why a headless cockroach survives for days. 🧠 Insects walk on the ground, so their nerve cord runs along the BELLY (ventral). Vertebrates keep it on the BACK (dorsal). Never swap the two.
Real NEET questions
NEET 2016 Phase 2
In male cockroach, sperms are stored in which part of the reproductive system?
A · Seminal vesicles ✓
B · Mushroom glands
C · Testes
D · Vas deferens
Solution: In the male cockroach a pair of testes (4th to 6th abdominal segments) sends sperm via a thin vas deferens into the ejaculatory duct through a SEMINAL VESICLE, where sperms are stored and packed into bundles called spermatophores. The mushroom-shaped gland is only an accessory gland that adds secretion and does not store sperm. So sperms are stored in the seminal vesicles - option A.
NEET 2020
If the head of a cockroach is removed, it may live for a few days because:
A · The head holds a small proportion of the nervous system while the rest is situated along the ventral part of its body ✓
B · The head holds one third of the nervous system while the rest is situated along the dorsal part of its body
C · The supra-oesophageal ganglia of the cockroach are situated in the ventral part of the abdomen
D · The cockroach does not have a nervous system
Solution: The cockroach nervous system is spread out, not packed in the head. The brain (supra-oesophageal ganglion) controls only a small part; most control comes from a chain of paired segmental ganglia joined by a double VENTRAL nerve cord along the lower side of the body. These ganglia work locally, so a headless cockroach survives for days. Option A is correct; B and C give wrong locations, and D is false.
Solved Structural Organisation in Animals NEET PYQs
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Is the cockroach reproductive and nervous system in the NEET syllabus?
After NCERT rationalisation, detailed anatomy of the cockroach was trimmed from the Class 11 text, but NEET has still repeatedly asked cockroach questions (2016, 2019, 2020) because they appear in the last few years' papers. So learn the key facts - seminal vesicle, mushroom gland, ovarioles, spermatheca, ootheca, ventral nerve cord - for one-mark safety.
How many spermathecae are in a female cockroach and where?
There is a pair of spermathecae (one pair) located in the 6th abdominal segment. They receive and store the sperm transferred by the male during mating.
How many eggs are in one ootheca?
One ootheca (egg-case) usually contains 14 to 16 fertilised eggs. The female may form several oothecae in her life.
What are the parts of the cockroach nervous system to remember for NEET?
Brain (supra-oesophageal ganglion) in the head, a sub-oesophageal ganglion, and a double VENTRAL nerve cord bearing segmental (thoracic and abdominal) paired ganglia. Key exam point: control is spread out, cord is ventral, so a decapitated cockroach can survive several days.
Is the cockroach male or female if it has anal styles?
Only the MALE cockroach has a pair of short thread-like anal styles on the 9th sternum. Both sexes have anal cerci, so cerci cannot tell the sexes apart, but styles are male-only. This links to the sexual dimorphism topic.
