Larval forms of Crustacea.

1. Larval forms of
Crustacea
K.Kamatchi
Assistant Professor
Department of Zoology
Vivekananda College
Tiruvedakam West

2. •Direct or indirect
•Egg – hatches – young one – resemble
– adult
•Egg – hatches – larval stages – adult

3. Nauplius
First larva
Free swimming
Minute and microscopic
Oval – shape
Cephalothorax, abdomen
Simple median eye
3 pairs of appendages
Uniramous
Biramous – antenna, mandible
Caudal fork
Under goes moults-
metanaupilus.

4. Metanauplius
Second larva
Develops from nauplius
Cephalothorax, abdomen
Caudal fork
Frontal sense organ
Median eye.

5. Protozoea
 Larva of prawn
 Develops – metanauplius
 Cephalothorax, abdomen
 Cepha – covered – carapace
 5 pairs of appendages
 Throax – 2
 Abdomen – no
 Telson


6. Zoea
Developes – protozoea
Free swimming
Minute, microscopic
Cephalothorax, abdomen
Carapace
Rostrum
5 cephalic app
3 thoracic app
Remain 5 buds
Abdomen – no – app
Telson

7. Mysis
Develops – zoea
Elongated, laterally compresed
Cephalothroax, abdomen
Carapace
Rostrum
All appendages developed
Differ from adult by brood pouch.

8. Cypris
• Develops – nauplius
• Triangular
• Bivalved shell
• 7 pairs of app
• Caudal spines
• Terminal end – antennules –
hooked
• Median eye
• Germ cells
• Short free swimming –
attached – crab – kentrogen
larva.

9. Kentrogen
Develops – cypris
Attached to crab
Like sac – cuticle
Chitinous tube – dart
Later stage – pierces
– body of crab

10. Alima
Modified zoea
Hatches out direct form egg.
Pelagic larva
Glass like transparency.
Slender body
Cephalothorax, abdomen
Carapace
Rostrum
All – cepha
2 – thorax
4 – abdo


11. Megalopa larva
 Larva of crab
 Develops – zoea
 Pelagic larva
 Cepha, abdo
 Carapace, rostrum
 Median spine
 Eyes – compound
 Megalopa - crab

12. Phyllosoma larva
 Directly – egg
 Glass –crab
 Modified Mysis
 Cepha, abdo
 Carapace
 Compound eye
