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Ask the Naturalist: What Is This Gelatinous Mass on the Juncus Leaves?

by Tony Iwane on December 19, 2017

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“Today I came across some terrestrial gelatinous egg masses suspended above the ground laid at the top of individual Juncus leaves. They are not located near a watercourse, so whatever hatches out is walking or scooting away over ground. There were hundreds of these egg masses, all suspended on Juncus, located in the forest on a skid trail from a recently logged area. The individual eggs are very small, probably about a millimeter in diameter.

Dominant trees include coast redwood, Douglas fir and western hemlock.  The skid trail has open canopy, so the egg masses are exposed to direct sunlight and air flow. Discovered near Caspar Creek on the Mendocino Coast. Who dun it??” – D C, Caspar, CA

Quite a mysterious find, D C. It definitely stumped me at first, so I brought it to the CCNH team and got the answer from Damon Tighe. While these do happen to be young versions of an organism, they are not eggs; rather, they are seeds from the very Juncus plants on which you found them!

I happened to be in the Mendocino area myself the exact same weekend you saw these masses, and I remember there having been some nice downpours over the previous few days – which is exactly what needs to happen in order for these slimy seed bundles to appear. It’s been documented that the seed masses of Juncus rushes, specifically Juncus effusus plants, can turn into gelatinous masses after some solid rain. Interestingly, I can’t find much other literature that delves into this bizarre phenomenon, so perhaps it needs just the perfect conditions to happen – like nice drenching rain just after the seeds have split, causing the starches in them to swell and congeal.

As you noted in your question, if these were amphibian eggs, they seemed to be in an unlikely place, given that anything hatching out of them would need to trek quite far before it reached a body of water. And that would certainly be true for the frogs and toads that live here in California, but not for all of our salamanders. Let me explain.

“Amphibian” comes from the Greek word amphibios, which means “living both on water and on land.” And when we think of amphibians, what first comes to mind is the life cycle of a frog or toad, the larvae (or “tadpoles”) of which have gills and need to live underwater. And eventually the tadpoles metamorphose into adults that can live on land and breathe air through their freshly-minted lungs. Many of the salamanders in California, such as our rough-skinned newts and giant salamanders, share a similar life cycle. And you’ll see their eggs laid either singly or in masses – resembling the Juncus seeds – but under water. If you go to a newt breeding pond later this winter, you may even see male newts scarfing down some eggs. Hey, easy nutrients!

But then we have the Plethodontidae, or lungless salamanders. As their name suggests, these salamanders never grow lungs; they instead rely on their porous skin and mouth for respiration, and don’t venture into the water. So yeah, basically not really living up to the name “amphibian,” but we’ll let it slide. Your standard plethodontid mother lays her eggs in a safe, damp place, such as under a log, and guards them until they hatch. The emerging young look pretty much like tiny, bespeckled, adorable versions of their parents and are ready to roll. While I’ve personally never found a plethodontid salamander with her eggs (and I long for such a day), the invaluable website California Herps hosts a series of photos that depict a pair of ensatina moms with their eggs and resultant super tiny hatchlings. Definitely check them out.

A very young ensatina. (Photo by Tony Iwane)

A very young ensatina. (Photo by Tony Iwane)

In addition to ensatinas, other commonly seen California plethodontids include the ubiquitous slender salamanders (Genus Batrachoseps) and the arboreal salamander (Aneides lugubris). You can find them under cover objects in pretty much any environment that’s wet enough. And because their skin is so porous it’s best to not handle them, as any chemical on you can make its way into their bodies.

I suppose that’s a lot of info about eggs that weren’t even in the photo, but finds like yours are what make exploring nature endlessly fun. You never know what you’ll see and where your curiosity may take you.

IMG_8346A resident of Oakland, Tony Iwane is the Outreach Coordinator for iNaturalist and an interpretive naturalist for the California Center for Natural History. Check out his photos on Flickr and his nature observations.

Ask the Naturalist is a reader-funded bimonthly column with the California Center for Natural History that answers your questions about the natural world of the San Francisco Bay Area. Have a question for the naturalist? Fill out our question form or email us at atn at baynature.org!

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