A Giant Named Tiny: Rearing a Giant Pacific Octopus

This blog post adapted from a presentation by Ali Redman, Aquarium Curator.

It all started out with the “Light Trap.” So I must begin this story with how we came to have a light trap and why. 

This past spring we joined the Pacific Northwest Crab Research Group, which is a diverse collaboration of crab researchers and managers who monitor larval recruitment of Dungeness crab using light traps with the goal of producing a sustainable Dungeness crab fishery. 

diagram of Light Trap used 
to count Dungeness crab larvae

The light trap is composed of a float attached to a 5-gallon water bottle with a light inside. Zooplankton enter through funnels, attracted by a light inside the water bottle. 

This past spring and summer, PTMSC staff and interns regularly counted the number of Dungeness crab larvae that were in the trap and reported that to the research group. Not surprisingly, lots of other kinds of zooplankton were also found in the trap. See the chart below for an idea of the diversity of “bycatch.”

Sample of diverse bycatch from the light trap

Even on the very first day, we found pelagic (floating in the water column) paralarval octopuses, both red Pacific octopuses and giant Pacific octopuses (GPOs). Raising octopuses from a paralarval stage in captivity is notoriously hard to do, and has only been done twice successfully. Keeping a pelagic paralarval octopus alive requires a kreisel or “jellyfish tank.” So we were not planning on collecting any octopuses from the light trap.

However, on June 10, we noticed an octopus zooplankton that was different. This female GPO was benthic, which means that she attached to things and crawled. We thought perhaps we could raise her without a specialized tank. We named her Tiny, because, well, she was tiny!

WATCH THIS VIDEO of Tiny the
octopus as a pararval zooplankton!

   

During phase 1 of raising Tiny, we used a “muck tub,” a piece of aquarium equipment used for larval fish rearing. It had fine mesh covering the drain and a lowered water level to keep her from climbing out. And because octopuses are so intelligent, we kept the tub stocked with a variety of decorations to stimulate her natural curiosity. Tiny ate a diet of wild caught plankton (zoea and other tiny crustaceans), and enriched brine shrimp.

Tiny the octopus started out in this muck tub!

When Tiny got big enough, we began weighing her weekly. We were very excited to see steady and vigorous growth. Her average growth rate was 2% of her body weight each day! 

Finally, when she was big enough (but still tiny, of course) she was moved to a tank in the aquarium exhibit. Astroturf around the rim and a weighted lid is now required to deter Tiny from wandering.

Here are a few fun facts about octopuses.

GPO vs red Pacific:

2 rows of dots on tentacles=red Pacific

1 row of dots on tentacles=GPO

Sexing Octopuses

Male octopuses have a hectocotylus, on the tip of the third right tentacle.

Tiny doesn’t have a hectocotylus, therefore Tiny is female.

Check out this video titled "Tiny over Time" which documents Tiny's growth during her stay with us here at the Port Townsend Marine Science Center:

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Athena and her toy!

Athena our Giant Pacific Octopus was brought to us back in October. She adjusted pretty well to her new home and seemed to enjoy human company. Lately however, she has been more active. We thought she might be bored, so we started giving her toys to play with and food in jars so that she would have something to do. Below is a video of Athena playing with her toy ball trying to get the food out.



Valerie Lindborg
Lab Coordinator

It's a Girl! (and a Boy! and a Girl! and a Boy! and a Girl! and a Boy!...)

One of the octopus eggs which is just about ready to hatch

As Jonathan and Julia were getting ready to open the marine exhibit today, they asked me to look at a Dungeness Crab who was laying eggs. I was curious about the crab--it seems like the wrong time of year to lay eggs. I took a small sample and put them under a microscope to see if they were developing and didn't see much.

It got me to thinking though. I wondered how Ruby, our little Octopus rubescens, was doing and if her eggs were viable or not. I took a quick peak at them yesterday and noticed that they were a nice peachy color. So I invaded her brood chamber and took 4 of her eggs. Right away I could see that they had eye spots and orangey-red dots on them. We put them under a microscope and could see the mantle pulsing and the chromatophores in the dots changing color. It was amazing!

Here is a short video of the larva inside of the egg.

Ruby laid her one to two thousand eggs on June 23rd and has been guarding them and blowing water on them to make sure they are well oxygenated since then. Although she came to our aquarium in March, she delayed the fertilization and laying of her eggs until she was secure and comfortable in her tank. Octopus rubescens are notoriusly hard to raise in captivity, but we will try to feed them artemia (brine shrimp) and see if we can be one of the first to raise them! I have to keep reminding myself that the reason many marine animals lay hundreds of eggs is that most of them will not make it to adulthood. Octopus are dedicated mothers and won't even eat while caring for their eggs. After she has witnessed her eggs hatching, Ruby will die.

Here is one of the newly hatched larva. This octopus hatched as I was moving the sample eggs to a petri dish. You can see the round yolk sac near the short tentacles.

We'll be sure to keep you posted on this unfolding drama. If you come by please ask us about these new babies, but remember that Ruby may still be in seclusion.

See you soon!

Chrissy McLean, Marine Program Coordinator