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Sunday, October 16, 2016

Adrift and brooding

While looking at some kelp holdfasts a few days ago, Eric's sharp eyes noticed a dark red blob with some smaller blobs along the edges:

A Proliferating Anemone (Epiactis prolifera)!  We were excited about finding this species because although Proliferating Anemones used to be common in the intertidal zone on Bodega Head, they disappeared around 2011 (perhaps associated with a harmful algal bloom at that time).  It's been years since we've seen one on Bodega Head.

Proliferating Anemones are external broodersthe adults brood juveniles along a groove near the base of the column (where the anemones attach to the substrate, e.g., a rock or algae).  Because they don't have a planktonic stage (the juveniles simply crawl away from the adult), it might take a long time for this species to recolonize Bodega Head.  Their best chance might be via rafting on kelp.

Here's a close-up of the adult anemone shown above with two larger juveniles on its right side (the anemones expanded once submerged under water):

And below is another view of even smaller juveniles nestled in the "brood groove."  The larger tentacles of the adult are visible at the top left corner of the photo.

Juvenile anemones will spend ~4 months being brooded by the parent.  One study I read estimated that Epiactis might persist for ~100 days on a kelp raft.  If the kelp washes up in appropriate habitat (e.g., in the rocky intertidal zone), the anemones might have an opportunity to move off of the kelp and onto the rocks.  (Yes, anemones can move!)

On 14 October 2016, we encountered quite a few kelp holdfasts washed ashore, perhaps transported from southern locations, as discussed in last night's post.  Many of the kelps were covered with small pelagic barnacles (Lepas sp.), indicating they had been adrift for at least a little while.  Not only did Eric spot the brooding individual shown above, but he found two other smaller Proliferating Anemones — one pink and one green:

While on the boat trip on 9 October, I photographed a raft of drifting Bull Kelp:

Perhaps there were some Epiactis on this raft?  If so, I hope some of them make their way to Bodega Head.  It would be nice to have this anemone around again.

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