শিক্ষামূলক নোট: এই পৃষ্ঠা একাডেমিক জীববিজ্ঞান শেখা ও পরীক্ষার প্রস্তুতির সহায়ক।
Study of Appendages — Cockroach and Prawn
Assessment emphasis: detachment + correct placement + course-sheet drawing + labelling + displaying.
A. Cockroach
1. Mouth Parts — Food Capture / Processing
| Part | Main role | Recognition |
|---|---|---|
| Labrum | upper lip; holds food | broad flap |
| Mandibles | biting/crushing | paired, hard, toothed |
| Maxillae | manipulate food | segmented palp + lacinia/galea |
| Labium | lower lip; manipulation | fused median structure + palps |
| Hypopharynx | tongue-like; salivary opening relation | median soft process |
Type: biting and chewing.
2. Legs — Locomotory
Three pairs thoracic legs; typical segments: coxa → trochanter → femur → tibia → tarsus → pretarsal claws/arolium.
Hind legs are not saltatorial like grasshopper; cockroach legs are cursorial/running type.
3. Antennae — Sensory / Prehensile-context caution
Antennae are primarily sensory, not true prehensile organs. Function answer-এ mechanosensory/chemosensory লিখবে।
4. Cerci — Defensive/Sensory
Paired posterior cerci air-current/vibration sense করে rapid escape response trigger করতে সাহায্য করে।
5. Reproductive/Copulatory Appendages
Male terminal genital structures/phallomeres copulation-এ ব্যবহৃত; female ovipositor-like gonapophyses reproductive passage/egg-case handling-এ অংশ নেয়।
B. Prawn
Appendage Plan
Typical crustacean appendage মূলত: protopod (coxa + basis) + endopod + exopod, তবে appendageভেদে reduction/modification ঘটে।
| Appendage | Main function | Key clue |
|---|---|---|
| Antennule | equilibrium + sensory | basal statocyst; biramous flagella |
| Antenna | sensory | long flagellum; scaphocerite |
| Mandible | food crushing | hard gnathal surface |
| Maxillula / Maxilla | food handling | small leaf-like mouth appendages |
| Maxillipeds | food capture/handling | thoracic appendages modified around mouth |
| Pereiopods | walking / grasping | 5 pairs; anterior pairs may be chelate |
| Chelipeds | prehensile / offensive-defensive | claw-forming pereiopods |
| Pleopods | swimming | paired abdominal appendages |
| Male modified pleopod | copulatory/reproductive role | sex-specific appendage |
| Uropods | rapid swimming / steering | paired tail-fan elements with telson |
Functional Grouping Required by Syllabus
- Locomotory: cockroach legs; prawn pereiopods, pleopods, uropods.
- Prehensile: prawn chelipeds; cockroach mouth appendages hold/manipulate food but “prehensile” should not be forced onto antenna.
- Food capture: cockroach mandibles/maxillae; prawn maxillipeds/chelipeds.
- Copulatory: male genital appendages; modified prawn pleopods depending on sex/species.
- Defensive/offensive: cockroach rapid locomotor/cerci-mediated escape + mandibles; prawn chelae, rostrum and tail-flip apparatus.
Course-sheet Placement Rule
Detached appendages:
- anterior-to-posterior order;
- left/right consistency;
- proximal end toward same direction;
- number each item;
- draw beside specimen, not over it;
- label homologous segments consistently.
5-mark Self-check
Before submission:
- correct appendage detached?
- intact proximal and distal ends?
- proper sequence?
- drawing proportional?
- labels readable?