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Dive Dry with Dr. Bill

#565: Little Squidlies

I wanted to write this week's column about one of my favorite critters, Loligo opalescens... but some time back it "disappeared" when those darned taxonomists, the biologists who classify critters, decided to rename it Doryteuthis opalescens. At times I get really tired of these often lab-based scientists who revel in renaming critters whose Latin names I had finally memorized after decades. They're almost as bad as that lovely lady who keeps changing her telephone number each time I call. Sigh. Fortunately many of us old timers still refer to this species by the older genus name Loligo.

I'm sitting here "watching" the Lions play the Packers via the Internet and keeping an eye on my 20 lb. Thanksgiving turkey while I write this. As my fingers do the walking on the keyboard (the sound of one hand typing as my students used to say), I think back to another meal I prepared for friends from high school, Harvard and Catalina when I was back in Chicago for the holidays. I slaved for a day over the sink and stove to create a gourmet meal... squid stuffed with various goodies... only to have many of my guests defer to the more familiar taste of chicken and beef.

What's the relevance, Dr. Bill? Well, Doryteuthis opalescens is the "new" scientific name for the market squid which are harvested by the squid boats we see off the coast of our beautiful island. Apparently this year there was a bumper crop and the fleet reached its quota very early. Unfortunately I have yet to see one this year (although they are still here), just a few "candles" of eggs, and therefore have had to resort to some great images taken by my friend and UW photographer extraordinaire Kevin Lee.

A few years ago I wrote a column about squid orgies. One reader complained to the publisher about the use of that word because she tried reading my column to her very young child. Well, the Monterey Bay Aquarium also uses that very word to describe the mating habits of these very interesting octopus relatives... and if it is good enough for that venerable institution, then it is good enough for my column! These cephalopods certainly do mate like my friends did at our Be-Ins and Love-Ins during the 1960s! Of course yours truly abstained from joining the Sexual Revolution of that era. Wink!

Without getting into the gory details, I wanted to look at the aftermath of all that strenuous activity on the part of the squid. Mated females lay egg capsules (often referred to as "candles") which may contain 180 to 300 individual eggs. These candles are often arranged in clusters, although the only candles I've seen inside the dive park have been individual ones. It is often said that the squid die soon after laying their eggs, but I have read reports that suggest at least a few may live until the next orgy... er, mating event.

Although the candles are generally laid above about 160 ft, there is a report of a fishing boat pulling them up from a depth of nearly 3,000 ft. Females insert the candles into the sand and a sticky substance anchors them there. I have seen extensive beds of these eggs as far as my eye could see (which my optometrist and the DMV claim is not that far). The candle itself is made of multiple layers of protein between which layers of bacteria grow and they give the eggs protection from fungal infections.

The individual eggs take three to five weeks to hatch depending on water temperature. The larvae that hatch out are referred to as paralarvae. After hatching, the yolk may sustain them for a few days but they must quickly learn to feed for themselves. Munchies consist of copepods and other small forms of plankton. After about two months of growth, they begin to form schools. At four to eight months they are sexually mature. In these later stages the squid feed on fish, crabs, shrimp and even smaller squid.

During the day, adult market squid may be found as deep as 1,600 feet. At night they ascend toward the surface in what is referred to as a diel or diurnal migration. They ascend into shallow water at night to take advantage of the increased food supply there and accelerate their growth, then descend during daylight to levels below where sunlight penetrates to give them protection from predators. Of course I descend under cover of darkness to look for predators... at least when the water is warm enough!

© 2013 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. You can also watch these episodes in iPod format on YouTube through my channel there (drbillbushing). 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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Market squid and a candle of 180 to 300 eggs; squid embryos developing in individual eggs
(all images courtesy of Kevin Lee).

This document maintained by Dr. Bill Bushing.
Material and images © 2013 Star Thrower Educational Multimedia