Golden eggs and purple pores

  

Sometimes when we're doing surveys, Eric has the camera while I'm writing field notes.  So when I download the photos later, they mostly show the species we're monitoring, but every now and then Eric sneaks in a different photo (and doesn't tell me)...so it's a surprise!

Here's a fun one -- a cluster of golden fish eggs on the left side, and a pretty purple sponge with prominent excurrent pores on the right side (the excurrent pores are the large diameter holes where water is pushed out after being filtered for food).

Thanks for the colorful photo, Eric! 

Photographed in the rocky intertidal zone in northern Sonoma County on 26 May 2024.

A clean sweep

  

Such a cool view of a peanut worm (Phascolosoma agassizii) collecting food particles off the surface of a sponge.  The peanut worm in the foreground has its tentacles extended and is sweeping them backwards (to the right) as it retracts its trunk-like introvert.

We've seen this behavior so often now that we're wondering if it's mutualistic — e.g., does the sponge benefit from having its outer surface "cleaned" of large particles and does the peanut worm benefit from having a smooth surface from which to collect food?

Among the sponges

Eric recently collected some calcareous sponges (Leucilla nuttingi) in the low intertidal zone for his Invertebrate Biology course.  In the past, we had noticed some isopods living inside these tiny vase-like sponges (see post called "Sponge surprise!" from 12 January 2012).  But last week in class, two students with sharp eyes (Maddy and Michael) noticed some other interesting animals living in association with these sponges:

 

Meet the amphipod Podocerus spongicolus!  This tiny amphipod is only 3-4 mm long.  Notice its very long 2^nd antennae.  The amphipods cling tightly to the outer wall of the sponge with the pointy tips (dactyls) of their thoracic appendages.  In the photo below, you can also see the shiny calcareous skeletal elements (spicules) shining through the body wall of the sponge:

 

This amphipod can be distinguished from other Podocerus species by the fact that article 4 (A4) of the male gnathopod (feeding appendage) is extended forward (see arrow in left figure below).   The photo on the right shows this same feature in the live amphipod:

 

As its name indicates, Podocerus spongicolus is known to be associated with sponges. Otherwise, it appears that little is known about this species.  We have only been able to find a few museum records of this amphipod (from the 1930s and 1960s). 

 

It is interesting to think about its life among the sponges.  Many thanks to Maddy and Michael for spotting these amphipods, Collin for identifying them, and Eric for taking the photographs! 

Cobalt blue

I haven't posted much about sponges.  That's primarily because they can be a little more challenging to identify.  The species featured tonight, however, is quite distinctive.

Sponges are animals and have skeletons comprised of elements called spicules.  Some species have spicules made of calcium carbonate, but most have spicules made of silicon dioxide.  The spicules are wrapped in elastic fibers that together make up the wall of the sponge.

As with the ossicles of sea cucumbers (featured previously), sponge spicules come in a diversity of sizes and shapes.  The characteristics of the spicules can often be used to identify the species.

This particular sponge can basically be identified by its color alone, but we also checked the spicules to confirm the identification.

Many encrusting animals in the low intertidal zone are variations of yellow, red, orange, pink, and sometimes purple, brown, gray, or white.  This one stands out because it's brilliant cobalt blue:

 

Meet the Cobalt Sponge (Acanthancora cyanocrypta)!

We noticed this sponge under a rock overhang in the low intertidal zone in Monterey County.  It's primarily a southern species (distributed from Monterey south), but has also been reported in British Columbia.  We haven't seen it in northern California.

Note the species name — "cyanocrypta."  This sponge has symbiotic cyanobacteria (which apparently contributes to the amazing blue color).  Crypta means hidden, so I'm guessing cyanocrypta refers to the cyanobacteria living within the sponge.

Now for the spicules.  Here's an example of the types of spicules in Acanthancora cyanocrypta:

 

Figures modified from The Sponges of California: A guide and key to the marine sponges of California (Lee, Elvin, and Reiswig, 2007).

 

Note the different shapes — the long, simple tornotes; the club-like and spiky acanthostyles; and the barbell-like amphiasters.

Eric took some nice photos of the spicules so you can compare.  Remember, the spicules are microscopic.  In the images below, they are magnified 400x.  See if you can find all three types of spicules in the next three pictures:

 

 

 

There are over 250 species of marine sponges in California, so perhaps we'll be able to feature a few other species in future posts.