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I hit the jackpot at the beach over the weekend! I was there to get some beached giant kelp to use as food for my snails and urchins. I found a fresh Kelp holdfast (not roots, but how kelp holds itself onto a rocky bottom) and it was loaded with critters! Holdfasts are home to whole communities of critters, mainly young animals. I found a purple urchin 3/4 of an inch across, a tiny kelp crab not more than 1/8th of an inch, many skeleton shrimp at 1/4 on an inch and a ton of tiny brittle stars in all shades of orange to red. Down at depth, up to 70 feet, the color red is not seen, so it's a great color for them to camouflage against the brown of the holdfast.
My jackpot was finding a string of eggs attached to a kelp strand above the holdfast. It looks just like a string of amber gems. Under the microscope each egg is translucent and has many fibrils attached to it's surface (see video). The fibrils attach to each other to form the long strand. Some of the embryos are viable (alive). The video shows the heart beating behind the head of one of them(see video). Unfortunately, they are too large for my microscope to get an overall picture of the embryos, so I have included a drawing from a book showing the embryo and fibrils on the egg, "The Early Stages of Fishes in the California Current Region, Atlas no. 33, Southwest Fisheries Science Center, La Jolla, Ca."
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head with eyes to left.
My research shows that they are a type of Silversides fish that look like grunions (but grunions lay their eggs in the sand), so probably a topsmelt. If so, the length at hatching should be around 5 mm, and they are around 4 mm now. So , could have some tiny fish soon! I have to do some research - they might be able to eat brine shrimp(which are easy to culture), but might also require something smaller like a critter called a rotifer.
So, please do enjoy the beach if you can. The ones in San Diego are open for now, but who knows when and if it will be closed again. If you do make it there, and happen to find a kelp holdfast on the beach, make sure to examine it closely. You may find a whole new world !
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