thecate hydrozoan, polarized light "display"

[Charles Krebs]

Friday, before I left the fishing dock where I use my plankton net, I scraped a small mass of diatoms off of one of the boat tie-up floats. Lots to see there! Buried inside the mass of diatoms were many of these hydroid colonies (at least that what they look like to me).

I took the first darkfield shot for a general "overall" and then was going to get in really close to look at the tip of a tentacle. When inserting the DIC polarizers it appeared that the tentacle tips contained some particles with birefringent characteristics. So I used a more "overall" objective and went to simple crossed polarizers.

Pretty neat! They lit up like as if they were filled with illuminated glitter. You could watch the "illuminated" particles flow up and down the hydrocaulus. The particles in the tentacles appeared to be fixed in position.

[discomorphella]

Hi Charlie---

Okay, the penultimate photo is so gorgeous that I was moved to do something I almost never do, try using an actual taxonomic key. In this case, Eugene Kozloff's "Marine Invertebrates of the Pacific Northwest", Univ. of Washington Press, c., 1987. On pages 44-57 are the keys to Hydroid polyps. I am going to say you have a member of either Clytia or Campanularia, with my guess going towards Clytia. I can't tell anything more since I don't think I can see any medusae being released. They do look at lot like Clytia bakeri that I've collected in San Diego before.
Simply striking pictures (can you tell how much I like finding birefringent phenomena in nature?).

David

[Aynia]

I love the darkfield.

If I ever do microscope stuff... it will be darkfield.. the arty look!

[Tom Jones]

Gorgeous Charlie! Built-in Christmas lights in June!!
Looks like another Small World/Bioscapes entry lurking here.

Tom

[Craig Gerard]

Certainly is a spectacle/spectaculum!

Craig

[René]

Very nice, Charles. Looks like Obelia to me.

Best wishes, Rene.