Question

1. Briefly describe the larvae of porifera, cnidaria, platyhelminthes, and nemertea in terms of morphology, feeding, and settling/metamorphosis. Note that these phyla may have more than one larval type, but you only have to discuss the type covered in class.

porifera=parenchymella

cnidarian=planula

Nemertea= pilidium

playhelminthes = Muller Larva

Answer 1

Parenchymella: This larva contains an outer layer of flagellated cells and a mass of internal amoeboid cells.At the posterior side we can see archeocytes.

It swims in the water or attaches to substratum.

Planula: They are flat,bilaterally symmetrical,contains cilia,free swimming form.

         They don't have digestive system.It can become a free swimming adult(Medusa form) or stationary adult to substratum if it becomes Polyp form.

Pilidium:

   It looks like helmet,cilia is present over the body.Its development appears to be catatrophic metamorphosis where juvenile larvae feeds on early larval stages.

Muller larvae: It is free swimming and eight armed larvae.

It appears as adult ctenophore.It contains many lobes ansd cilia is present on their body.