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. February 15, 2013
Warm, calm, a brilliantly sunny day. Spring stirs us all, including the Hooded Nudibranch, Melibe lionina
, as I discovered while gazing into the still, greeny depths of Barlow Bay. While my better half was checking the buoy mooring line and spiffing up our sailboat (the Blue Penguin), I was drifting over the eelgrass bed surrounding it. Not a breeze, for a moment, to riffle the surface, and at this time of year quite good visibility, as the plankton has not yet begun to bloom. What a pleasure to see Melibe
, attached to a strand of eelgrass, its favorite haunt.
Melibe leonina on eelgrass, Zostera marina
Barlow Bay is one of the most protected spots in the Salish Sea, which is why we moor here. That protection, and the sandy/muddy bottom, promotes a lush eelgrass meadow throughout much of this shallow bay, and all the many creatures that make a living in it. The Hooded Nudibranch is one, anchoring itself with its characteristic single gastropod foot. But this sea slug is very different otherwise. It casts a large expandable hood out into the water, waiting for passing amphipods, small fish, jellyfish and such to tickle its tentacles, then snatches them into its mouth. Carnivorous, like all nudibranchs. But as delicate as a cobweb. Melibe
gets thrashed in rough water or surge, so quiet bays or deep water are where you'll find it. Being so fragile, it needs an array of tactics to avoid predation itself. If Melibe
gets dislodged, it can swim, by undulating its angel-like body. It can also cast off its appendages as a distraction, and exudes a distinctive scent when touched (a very pleasant one to me, like watermelon). Here's an underwater video of it, filmed about 50 miles west of here.
As I watched, trying to get a good picture, I saw more.
tricky taking photos from a drifting kayak
And more. In fact there were swarms of them.
Melibe and egg case
They were mating - exchanging sperm, since they're hermaphrodites - and spawning. This is it for them...they live only one year, and die after fastening their egg cases to eelgrass. From the look of it, in a week or so there will be hundreds of dead translucent wispy nudibranch remains drifting and dissolving in the bay. Baby nudibranchs will hatch later in the spring.
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Life and death and birth, the natural order of things. With the biological imperative fulfilled successfully.
I saw some more kinds of nudibranchs later that afternoon, walking on the beach (what can I say, I have a great fondness for nudibranchs)... I'll show you soon.
So, what's going on in your backyard - on the ground, in the water, up in the trees, in the sky? Where are you and what do you see?