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Dive Dry with Dr. Bill

#459: Eggs... Ceptional!

Despite immersing myself "down under" for almost 50 years now, there are a number of things I have yet to see in King Neptune's realm. I've had many sharks swim by me, observed giant sea bass courting, filmed kelp bass munching on blacksmith, watched as a cormorant swam under my legs looking for tasty tidbits, and filmed a host of species doing "the wild thing." But there is one thing I'm absolutely shocked that I've never seen... an octopus nest.

I've filmed octopus feeding on crabs and other munchables, recorded their kitchen middens (the piles of empty shells and other discarded food items they leave), captured them using wavy top snail shells like a cork to plug up their holes and protect them from nosy (and hungry) kelp bass, chronicled one using a kelp crab as a defensive shield against a hungry moray, videotaped them inking as some moronic diver tried to grab them (it wasn't me!) and taken footage of one digging a burrow in the gravely bottom to escape from predators (only to have it collapse on him/her when finished). I've filmed them mating... and even captured one female rejecting a potential suitor by spraying him with her ink and retreating into a crevice! But I've never, ever even seen an octopus nest... much less brought home images of one to share with you.

Fortunately I have established friendships with many excellent underwater videographers and still photographers who permit me to use their images in my columns and videos. Even my high definition video camera cannot record the fine detail that a good digital still camera is capable of. I've been able to watch video of a GPO (giant Pacific octopus) guarding its nest up in Puget sound, then "observe" the young as they hatched from the eggs on YouTube. Given the size of a GPO (not quite as big as a GTO), maybe that is one nest even I could find! Recently, two friends (Phil Garner and Merry Passage) posted pictures of the nests and eggs from one of our local octopus species on Scubaboard.com and granted me permission to use them in this column. Thanks Phil and Merry.

I rarely do mainland dives since I'm not a fan of entering or exiting the water on sandy beaches. They have nasty things like surf that can knock this old geezer down, and grit that gets into one's regulator requiring far more frequent maintenance than this divebum can afford! Phil and Merry were diving the Redondo barge and landing craft in September and came across not one, but two octopus nests close together. The females usually seen guarding the nests were gone, so Phil and Merry were able to get some fantastic closeups of the eggs and you can even see the youngsters developing inside them.

Based on what I've seen, octopus courtship and mating is pretty rough and tumble. It far exceeds what I've seen at Luau Larry's. With eight arms to grasp one's mate, it can be a pretty "twisted" affair. The male's third arm on the right is actually a specialized organ known as the hectocotylus with a structure known as the ligula near the tip that is used to transfer sperm packets (spermatophores) to the female. This structure is actually erectile, and becomes engorged with blood when it is time to mate. Our octopus are the only invertebrates known to possess erectile reproductive organs. In addition to inserting packets of his sperm, the male may also use the ligula to remove sperm packets deposited previously by other males to ensure his lady gives birth to his offspring... at least until the next male comes along with the same idea.

Once inseminated, the female retreats to her shelter hole and lays her eggs. Some reports state as many as 150,000 eggs can be laid, but several thousand is the norm for our two local species, the California and the Verrill's two spot octopuses. The eggs are attached to the wall or ceiling of the female's shelter hole by thin stalks. The size of the eggs and length of the stalk differs in the two species. The female then tends her eggs for one to four months until they hatch. The time probably depends on factors such as water temperature.

The California and Verrill's two spot octopuses also differ in the hatchling's status and behavior. The Verrill's eggs hatch into larval forms that enter the plankton and may disperse with the currents. It is this species that is most common on offshore islands like Catalina. Those of the California octopus hatch into miniatures of the adult and remain close to home on the mother's reef. Hence they are less likely to reach offshore islands unless they disperse on drifting kelp or other such mechanism. In my research during the 1960s and 1970s we did find an occasional octopus juvenile transported in the holdfast of drifting kelp, but could not identify which species they were (it takes very close examination). Heck, back then I wasn't even aware there were two species of the two spot octopus!

It is reported that the female does not eat while she broods her eggs. They become weakened due to lack of nourishment and often die, which may explain why the two females were missing from the nests Phil and Merry filmed. Some sources have stated that a few females may survive and breed a second time. However, most are dead by three years of age. Several years ago I was filming garibaldi nests in the dive park and came across three of them each with a dead octopus stuffed into a hole nearby. Each cephalopod had obviously been bitten into. Perhaps these were dead females, rather than ones killed for food by the garibaldi. I wondered if the male garibaldi defending his nest used them as a stash of nourishment while he aggressively defended his nest. I should write a grant proposal to study this!

© 2011 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 29, 10:00 AM weekdays and on Charter Communications Cable channel 33 at 7:30 PM on Tuesdays in the Riverside/Norco area. Please help me climb out of self-imposed poverty... buy my DVD's (see this link). Yes, take Dr. Bill home with you... we'll both be glad you did!

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The rough-and-tumble sex life of the eight armed octopus (upper left) and
eggs in the nests as photographed by Phil and Merry.

This document maintained by Dr. Bill Bushing.
Material and images © 2011 Star Thrower Educational Multimedia