As the senior aquarist of animal health at Birch Aquarium at Scripps Institution of Oceanography, Maddy Tracewell often gets a close-up look at some of the ocean’s most captivating and odd creatures.
One of which was a vibrant female red octopus that the aquarium acquired last year.
“Our plan was to put her on display so that the public could see her,” said Tracewell on Friday. “But about, like, a month after we received her, she laid eggs.”
Tracewell didn’t know that what came next would turn into one of the most peculiar moments of her time at Birch.
“I was looking in the tank and I could see, like, little tiny red eyes looking at me, and I was like, 'oh my God, they’re fertilized,'" she said.
Six months ago, those eggs hatched into planktonic paralarvae, the stage when they look like miniature aliens, smaller than a grain of rice. But today, they’re the size of a thumbnail and look more like tiny octopuses.
More excitingly, the octopuses have settled. That means they’re exploring the seafloor of their home at the aquarium.
Birch officials said they believe this marks the first time the species has been hatched, raised and settled in aquarium care. It’s a breakthrough moment for the aquarium, which is located within one of the world’s most renowned oceanographic institutions. That’s because scientists rarely get to see how the red octopus transitions from a free-swimming being to a settled voyager.
“There's only about, I want to say, six small-egg octopus species that have been raised in captivity,” said Tracewell. “So, there's just not a lot of knowledge about this stage of their life.”
To help raise the baby octopuses, Tracewell had to replicate nature. Before they settle, the planktonic paralarvae spend many weeks drifting with ocean currents.
Tracewell found a way to mimic the currents. She built an upwelling system using polyvinyl chloride, which gently moves water from the bottom of the tank upward, to help the babies stay in the water column.
She said she dug through research papers and sought the help of cephalopod colleagues and scientists.
Tracewell also had to figure out what to feed them. Officials said they typically feed young species live brine shrimp, but learned they lacked a specific fatty acid needed for the octopuses’ development. So, they turned to a different shrimp species.
“After completing my research, it became clear that live foods commonly used in aquariums didn't have the right nutrient profile for growing paralarvae,” said Tracewell. “So we had to grow our own food. Our live food aquarist created a Grass Shrimp culture that produced baby shrimp that we could feed to the baby octopuses (paralarvae).”
Red octopuses are native to California. They typically live for about two years.
Tracewell said she hopes that once the red octopuses have grown to at least an inch in size, the aquarium will display them to the public.
Birch Aquarium currently has a Giant Pacific octopus, two California Two-Spot octopuses and cuttlefish, which also belong to the group Cephalopoda.
