Guess who?

 

This is an extreme close-up.  Do you have any guesses about what type of animal it is?

The next photos show zoomed out views that might provide more clues. Hint: The phylum that this animal belongs to is known for being spiny.

 

Any ideas yet?  

You can see lots of small rounded spines.  Scattered among the spines are tiny claw-like pincers called pedicellariae.  The large white spot is a special structure called a madreporite (or sieve plate).

One more view before I show the entire organism:

 

Okay, here you go...and the answer is: 

 

It's a Six-armed Sea Star (Leptasterias sp.)!  It was fun to photograph close-ups of this species in the field.

I mentioned a few different structures above.  To learn more about the pincers or pedicellariae, check out these posts:

"Armed with pincers" on 5 March 2013

"A star from the depths" on 10 September 2014

"In a pinch" on 22 August 2013

And if you're interested in learning about madreporites or sieve plates, you can start with these posts:

"Spiny and groovy" on 14 June 2018

"Take five" on 7 May 2013

 

In a pinch

The predator approaches from below:

 

The prey reacts:

 

In this case, the predator is a Sunflower Star (Pycnopodia helianthoides) and the prey is a Purple Sea Urchin (Strongylocentrotus purpuratus), photographed on the Mendocino coast on 22 August 2013.  

In the photo above, note that the sea urchin has flattened its spines and extended its pincer-like pedicellariae.  The pedicellariae look like little white stars among the purple spines and tubefeet.  

Although small, the pedicellariae can be very effective deterrents against larger predators such as Sunflower Stars.  The pedicellariae pinch and they contain toxins!  [The toxins in Purple Sea Urchin pedicellariae are not harmful to people.]

The next image shows a better view of the urchin's pedicellariae. 

 

This urchin was in "full defense mode", which made it easy to photograph the exposed pedicellariae.  In these images you can clearly see the three-parted pedicellariae spread wide open, ready to fend off the approaching sea star.  In the still photo below, the pedicellariae look delicate and flower-like, but it's more appropriate to think of them as menacing and dangerous!