Monday, June 6, 2011

Pseudocyphonautes of Flustrellidra

These pictures are of the bryozoan Flustrellidra coniculata and its pseudocyphonautes larva. The pseudocyphonautes resembles the planktotrophic cyphonautes larva of some bryozoans in that it has a bivalve shell. But it is lecithotrophic (non-feeding) and is brooded. The top picture shows the bean-shaped pseudocyphonautes larva using a dark-field technique. One can distinguish the cilia of the corona ciliata along one edge of the larva. One can also see a ridge on the opposite side which corresponds to the shell margin. The clear outer coating is the shell that protects the larva’s interior structures.

The middle picture shows a small section of the colony (with zooid lophophores retracted). The three white oval shapes out of focus are the larvae which I have dissected. Just beneath the surface of the colony one can see a few yellowish-white masses. These are the ovicells, specialized zooids for brooding eggs and larvae. I extracted the pseudocyphonautes larvae by puncturing the ovicells with a pair of fine forceps and squeezing gently to push them through the hole.

The bottom picture shows a complete Flustrellidra colony, with my palm for scale. This is the largest upright bryozoan colony I have ever seen. It does not look like a bryozoan at all. In the field I would have easily mistook this animal for some sort of alga or a sponge!

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