Argonauts are astounding!

This ocean creature wasn’t on my radar screen until a female argonaut rode a warm current up to Southern California and was caught by squid fishermen who then contacted Cabrillo Marine Aquarium, which is where it now resides and where I first heard about it. Argonauts are common in tropical seas, but not off California so this was a surprising and exciting find. The more I learn about argonauts, the more and more it seems like they are aliens from outer space, but really they are argonauts from ocean space…(read in the same way as the opening and closing line in the classic “Pigs in Space” muppet sketch).

Here are five amazing argonaut facts:

1. Argonauts are a species of octopus.

2. Female and male argonauts are very different sizes, meaning scientifically they exhibit a dramatic case of sexual dimorphism. Males only grow one inch while females grow up to 18 inches long. That’s right, you read the numbers correctly, males = 1 inch, females = 18 inches. (Sexual dimorphism is a term that means females and males of the same species have different traits, this includes different sizes, colors and/or behaviors.)

3. A female argonaut creates a thin shell to use as a brood pouch for eggs. This shell is secreted and formed by a modified arm that has a wide sail-like lobe, which stands out from the other seven “normal-looking” arms.

4. Males also have a modified arm called a hectocotylus. During mating, this arm breaks away on a mission to carry sperm and crawls into the female where it just hangs around until she is ready to fertilize her eggs! (The female then carries the fertilized eggs around in her shell until they are ready to hatch.)

5. Argonuats swim about in warm open ocean areas eating krill, shrimp and pelagic snails.

There are many things waiting to be discovered about these amazing creatures. In the meantime, check out the YouTube video above posted by Cabrillo Marine Aquarium. It starts with the head of the female argonaut sticking out of the shell, then suddenly her whole body leaves the shell and reveals she really is an octopus. It’s wild!