Picture of the Week

Lobster Phyllosoma Larvae - (Palinuroidea)


© 2000 by Image Quest 3-D
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© 2000 by Image Quest 3-D
Read our copyright notice
Phyllosoma larva
Phyllosoma larva balancing on mini hydromedusan

 


© 2000 by Image Quest 3-D
Read our copyright notice

 

Phyllosoma larva riding upon Moon Jelly (Aurelia aurita)

 

Illustrated here are lobster phyllosoma larval stages, superfamily Palinuroidea. These particular individuals were photographed off Lizard Island on the Great Barrier Reef, Australia.

Among no group of marine animals is metamorphosis more spectacular than many of the crustacea and amongst them the most bizarre story comes from our old friend the lobster, in particular the spiny lobster and slipper lobster. From the eggs that the female carries beneath her abdomen, hatch small and very flat, transparent and spindly larval phyllosomas, literally 'leaf bodies'. So long-legged are these animals, with their gawky stalked eyes (see above left), that they always seem cumbersome and inept. In reality they are dead smart and should take the prize for cooperative living and long distance hitch-hiking. They have devoloped a really neat adaptation to assist with their unique lifestyle. While existing as larvae in the plankton community they attach to a jellyfish or hydromedusan by grabbing hold with all four pairs of legs (see above centre). If the jellyfish begins to drift the baby lobster cannot propel itself around because all of its limbs are needed to hold on. Therefore, they have adapted and developed a side branch to each limb that ends in a feathery paddle which can be used independantly for movement (see above left).

By the time the phyllosoma is over a year old it may be five centimetres wide. Upon arrival in shallow waters the larval lobster swims free and begins its metamorphosis by discarding at least three quarters of its larval body. Curiously the part of the larval phyllosoma that forms the first stage of the difinitive but miniture adult lobster is the hind end. The front end of the phyllosoma, complete with stalked eyes, fused head and shoulder, as well as all the main limbs, remain as the discarded preambulator, to drift away, twitching in the water column until some predator snaps it up. The hind end settles out into a very small, only half a centimetre across, transparent yet perfectly formed lobster still drifting at the surface. Gradually it will descend to the substrate to find shelter and protection while its pigmentation develops to aid camouflage and it continues to grow into an adult.

 

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