....but just for a few days. I won't see them again til next year. It's a silent drama of individual risk and species survival in this quiet bay, especially in the face of new competition.
The Daily Bucket is a regular feature of the Backyard Science group. It is a place to note any observations you have made of the world around you. Snails, fish, insects, weather, meteorites, climate, birds and/or flowers. All are worthy additions to the bucket. Please let us know what is going on around you in a comment. Include, as close as is comfortable for you, where you are located.Barlow Bay, Salish Sea, Pacific Northwest Early September, 2013
At least I thought they were nudibranchs until I got a close look. Unlike their fellow gastropod, these carried small transparent shells on their backs, which means they are snails instead. In the photo above, the snail is climbing up the leaf, and the more orangey part in the middle is the shell. Needless to say, it's too small for the snail to fit its entire body into. These are Bubble Snails.
Here's an empty shell, and a living Bubble Snail on my hand, attempting to withdraw into its shell as much as it can (I put it back after the photo). The shells are so delicate they usually crumble into sand before they wash up on the beach.
Except at this one time. They climb up onto the eelgrass in their thousands to cavort and lay their eggs, throwing caution to the "winds". They leave these bright yellow coils behind, each containing about 500 eggs.
Unlike algae (kelp, seaweed, what have you), eelgrass is actually a flowering plant with vascular tissue, the fibrous tubes that carry food and water in almost all our land plants. Makes it less useful as a garden fertilizer than the algae I use, which dissolve straight into the soil. But it's a sturdy support for the White Bubble Snails (Haminoea vesicula) who were choosing it today for their massive mating event.
Eelgrass beds are filled with life, a three-dimensional "forest" of gently moving water, tons of organic material (including dead eelgrass blades) and a complex ecosystem. The grass is a substrate for crawling things and protection for swimming things. It gathers sediment and holds it with rhizomes anchored in the sandy mud. Eelgrass meadows moderate the force of waves, protecting shorelines.
Almost always it's under water and a casual observer won't even notice it. Here's a view across the bay at a low tide. Directly offshore the beach is some open water, then a "grassy" zone. This is the top of the eelgrass.
(As a side note: I feel a little weird hanging over the side of the kayak spying on creatures having sex, taking their picture and posting it on the internet. Snail pron. The things we find ourselves doing in the name of science...)
I was able to positively identify these as Haminoea vesicula by the shape of their head: posterior more like a short cape than folded back bunny ears (these pics don't show that very well but I took lots just for ID purposes). It is wonderful see native Bubble Snails in Barlow Bay, rather than the very similar introduced species, the Japanese Bubble Snail Haminoea japonica, first identified in Washington waters in the 1980s, possibly brought over with Asian shellfish.
H. japonica has a survival advantage over H. vesicula: while the eggs of both hatch into planktonic larvae that can drift afar (see the microscopic veliger larva in the photo), some Japanese Bubble Snail eggs can also hatch as crawling youngsters who have a head start in a friendly habitat like this one. There are very few species that have this capability, and our native Bubble Snail may have some serious competition in future.
Time for your observations. Anything unusual you're seeing as we slip from summer into fall? Or are your regulars coming and going as you've come to expect?
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