The document describes several larval forms of crustaceans: - The nauplius is the fundamental larval form, with an oval unsegmented body and three pairs of appendages. It undergoes molting and transforms into the metanauplius stage. - The metanauplius has an elongated body with frontal organs and rudimentary appendages. It molts into the protozoea stage. - The protozoea has a differentiated cephalo-thorax and abdomen, covered by a carapace. This develops into the zoea stage, which is the second important larval form with a developed cephalo-thorax and six-segmented

1. LARVAL FORMS
OF CRUSTEANS

2. NAUPLIUS
 Nauplius is the first and the fundamental larva of most of
crustaceans.
 It is minite,free swimming,pelagic larva.
 It’s body is oval and unsegmented,with a median dorsal eye and
three pairs of unjointed lateral appendages ,namely
antennular,antennary and mandibular appendages

3. Antennular appendages are uniramous, and
the others are biramous
Anus is located at the posterior tip
Nauplius undergoes repeated moults and, in
most crustaceans, transforms to the
metanauplius stage

4. Metanauplius
Metanauplius represent an advanced stage of
nauplius
It’s body is elongated, with an oval cephalo-
thoracic region and a terminally forked
abdomen
Anteriorly, cephalo-thoracic has a pair of
papilliform frontal organs

5. Ventro laterally, there are the paired
antennular,antennary and mandibular
appendages and the rudiments of four pairs of
appendages

8. Protozoea
Protozoea has an enlarged and elongated
body, differentiated into cephalo-thorax and
abdomen
Cephalo-thorax is covered by the carapace or
dorsal shield

10. Zoea
Zoea is truly an advanced protozoea
It is the second important crustacean
larva
In zoea, the cephalothorax becomes
much developed and the abdomen
becomes six segmented

11. The median eye of the protozoea disappears,
but the compound eyes become stalked and
movable

12. • ALIMA
In squilla, the embryo hatches out from
the egg as a modified zoea known as
kalima larva
It is glassy and transparent pelagic larva,
with clean body covered by short and
broad carapace

13. Carapace bears a rostrum
Body has three divisions head,thorax and
abdomen
Head bears the antennules,antennae and the
stalked compound eyes

14. Music or schizopod
Mysis is found in the life cycle of Pegasus
It’s body is long and lean with an elongated and
six segmented abdomen
Abdomen appendages make their appearance
and develop to biramous pleopods swimming
legs
The last pair of swimmerets eventually transform
to uropods

16. Megalopa
Cephalothorax is large and crab like,with well
developed appendages, large and stalked
compound eyes and a carapace produced into
a rostrum
Abdomen is six segmented with functional
pleopods