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Meet the unbelievable worms of the bay

I feel I noticed a worm swimming within the bay, what’s it?

It was in mid-August 2015 after I first held her lengthy thread as a physique rolling and throbbing in my hand. Tickled by the anticipation of a chunk or a sting, my blood pump was duplicated, as sweat ran down my nostril and blended with the salt water of Merritt Lake in the summertime. The unusual, small, vivid orange organism that I picked up from the floor could be my first introduction to a seasonal occasion, within the waters of San Francisco Bay, of a novel sexual replica technique utilized by a few of our most uncared for bay: the polychaetes.

Additionally known as marine worms or hair worms, polychaetes are a part of the phylum Annelida, segmented worms. The San Francisco Bay has greater than 100 totally different species, some originating from distant and transported right here within the ballast waters of the transport boats. Megasyllis nipponica, the one I stored, is from Japan. Most polychaetes spend their lives on the backside of the bay within the mud, within the rocks and in different nooks to which their slender physique permits them to achieve. So why was he swimming on the floor?

Megasyllis nipponica grownup worm. The pinched part is the place to begin of the epitoke and a slight coloration change can be in progress for this posterior part. (Photograph by Damon Tighe)

On the finish of the summer season, quite a lot of
polychaetes undergo a synchronized reproductive course of known as epitoky
the place grownup worms produce sexually mature worms that swim and are visibly
totally different from the unique worm in type, coloration and dimension. A way of
producing epitokes consists in accumulating gamete materials (eggs and sperm) in
posterior worm after which budding new worms right into a course of often known as
schizogamy. M. nipponica who’s normally
green-colored budding vivid orange epitokes that swim furiously by way of the
water searching for different epitokes. When epitokes are discovered, generally
burst, permitting eggs and sperm to fertilize one another.

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Swarms of epitapids happen a handful of occasions a 12 months when the water temperature is appropriate and, for some species, the moon part comes into play. M. nipponica appears to desire the brand new moon in August and September, when the waters of the bay are the most popular. Swarms have been recognized world wide for hundreds of years. Christopher Columbus would have seen bioluminescent epitokes of the genus Odontosyllis on his first journey to the Americas, whereas Polynesians have lengthy been harvesting swarming worms invading the South Pacific for caviar-like meals.

Megasyllis nipponica epitoke. (Photograph by Damon Tighe)

Not one of the Bay's polychaetes appear to make big demonstrations with lights, or epitokes giant sufficient to choose up and eat, however brightly coloured worms are a phenomenon to observe as the tip of summer season approaches. .

Ask the Naturalist is a bimonthly column funded by a reader, printed by the California Heart for Pure Historical past, that solutions your questions in regards to the pure world of the San Francisco Bay Space. Do you’ve a query for the naturalist? Fill out our query type or e mail us at atn at baynature.org!

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