Shellfish Breeding and Hatchery Management (2+1)

16.2.1 Larval development of lobster

Egg: The eggs are adhesive in nature. (Brick red colour)

Embryonic development:

It takes place inside the egg.

In the embryo 16 development stages have been observed during early embryonic development. The egg passed through all these stages before hatching into phyllosoma larvae. The total time taken for embryonic development and organ formation depend on temperature. It took 8-20 days at temperature of 31⁰C & 25-26⁰C. The brick red colour of egg changes into orange red, light yellow, and finally egg colour changed to light brown colour.

Stage I – Undeveloped and appeared brick red

Stage II – Cleavage of eggs

Stage III – Yolk utilization

Stage IV – IX – Developing egg passed through blastula, gastrula stage. During this stage much of the yolk will be utilized

Stage X – non- rhythmic heart beat can be seen in the dorsal part of the egg. 60% yolk consumed indicating the development of different organells. Egg mass become brown.

Stage XIII – Full differentiation of eyes.

Stage XVI – Fully differentiated larvae can be seen.

Egg mass appear dark green black in this stage. After complete development, the phyllsoma larvae hatched out of the egg in the surrounding water.

Phyllosoma larvae:

The size of this larva is very large, having head, throax, abdominal regions and is transparent as glass. A large carapace covers the first two thoracic segments and head. Abdomen is very much reduced and may be indistinctly segmented, but without appendages. The antennae and maxillae are degenerating before hatching. The seventh and eight thoracic appendages and abdominal somites are indistinct in the larvae. even through they are well defined in the embryo. The first thoracic appendage is rudimentary second is uniramous. The phyllosoma undergoes several moults before becoming an young adult. Duration of this stage is 90-250 days. There are 7-13 phyllosoma stages (some times a pre-phyllosoma, & pro phyllosoma).

These stages last for not more than few hours. The larval periods of palinurids ranging from few months to almost 2 years before it reaches last phyllosoma stage (about 35 mm in length).

Puerulus stage (7-56 days, I - stage)

After 6-24 months, the planktonic larval stage metamorphoses into the puerulus stage. It is transparent, free swimming, non feeding post larval stage that moves inshore is where it settles to the benthos.

Subsequently through ecdysis, puerulus becomes adult which leads a nectonic swimming life with well developed appendages.