Some neat 20D supermacro

It's really neat to discover critters in supermacro shots that you didn't intend to shoot. Sometimes the critters are so small that you can't see them with your naked eyes. I took a shot of some polyps growing on a rock and discovered ant size shrimp grazing on them. I also discovered pinchers that look like something out of a sci-fi on the surface a common blue starfish.

http://www.pbase.com/wychen/uwsci050705

Cool stuff!

I believe those pinchers actually BELONG to the starfish. It uses them, along w/ its tube feet for gripping.

Cheers

James

Will - AFAIK, those "polyps" are small sea cucumbers in the rock.

Again, some nice shots. I'll be out on the Peace this Sunday, (hopefully) to San Miguel...you'll have to let me know how the vis is

~Matt Segal

Actually, those pinchers are called pedicellaria and you have done very well to photograph them!

As James correctly notes, pedicellaria are part of the seastar. They are also found on some sea urchins. In seastars, pedicellaria are "two-jawed" and in urchins, they are "three-jawed." One species of tropical urchin with only has a few spines actually has highly poisonous pedicellaria which have killed people handling them (Look out for Toxopneusta sp).

It is generally thought that the seastars use the pedicellariae to keep themselves clean free from fouling (kinda like a really aggressive antifouling system) by picking off anything that settles (eg. larvae) on the surface on the animal. They are essentially a modified version of the spines on the seastar surface and act like little pincers as you observed.

I'm not quite so sure about the sea cucumbers id by Matt, but I'm happy to be proven wrong. To me, they look more like a member of the phylum Cnidaria, but being an Aussie, and never having seen them before - maybe I've just got things topsy turvy??

I don't know any of the scientific stuff........but nice pictures

Hey Will, what lens/setup did you use for your shots?

Sorry, Matt. Will & Anthony are right on this one: the polyps are really polyps, some kind of octocoral as there are 8 branches. The tentacles in cukes usually come in multiples of 5 and there would be noticeable muscle bands along the body.

I agree, nice photos. Will, can you get a decent enlargement of the shrimp on the polyps? I'm curious about them. Thanks, Leslie

I don't know what are exactly those polyps but you have a nice gallery, congratulations!

cukes = sea cucumbers??

thanks for the input Leslie - always good to have someone with fantastic knowledge such as yours.

I hope this works. Attached should be a 66% crop of the shrimp. The polyps are probably about and 1/8-1/4 inch wide at the base to give you some perspective of the size of the shrimp.

This was shot with a Canon 100mm macro.