by Mary Jo Adams '99
There are always lots of interesting things to find and learn about on our Island County beaches. A friend recently emailed a photo showing a cluster of white tube-shaped masses that had washed up and asked, “What are these?” They turned out to be egg capsules from the market squid (Doryteuthis opalescens*). Also known as the opalescent squid, this species ranges from SE Alaska to Mexico’s Baja Peninsula. It grows to a length of about 11 inches and has the 8 arms and two longer tentacles typical of squid. Both the arms and tentacles have suction cups although on the tentacles, they are found only at the distal tips. Unlike some of its larger deep water brethren, the suction cups of this species do not bear hooks.
Market squid spawn in the shallows over areas of soft sandy or muddy substrate. The female expels about 20 of the finger-sized gelatinous egg capsules, each containing 180-300 eggs. The egg capsules are formed in layers and include a bacterial symbiont that is protective of the eggs. Scientists believe this symbiont inhibits infection by bacteria and fungi, and also repels larger animal predators that may view the eggs as an easy meal. A male hands off packets of sperm to the female before the egg capsules are produced and the sperm are then released to fertilize the eggs. After fertilization, the female attaches her egg capsules to the substrate. Many squid congregate to spawn and as a result egg beds may cover several acres. The egg beds have been described by scuba divers as having the appearance of white shag carpet.
Hatchlings emerge in 3-8 weeks and each is about 3 mm long. To put that in perspective, the average grain of rice measures 8 mm in length. The tiny squid are predators and have to immediately get to work finding food. They hone their predatory skills on copepods and other planktonic organisms. As they grow larger and hunting skills improve they move on to other small crustaceans, small fish, polychaetes, and shrimp, and they are known to cannibalize their own kind. Market squid reach sexual maturity at 4-8 months and their lifespan is less than a year.
Market squid are an important part of the food web. Adults die shortly after spawning and many scavenging organisms such as crabs and sunflower stars gather to feast on them as the mass die off occurs. This species also falls prey to pinnepeds such as the California sea lion and northern elephant seal, cetaceans including Dall’s porpoise, birds such as the Brandt’s cormorant, Heerman’s gull, common murre and rhinoceros auklets, and such fish as lingcod and plainfin midshipmen. You too have probably consumed this species if you have eaten calamari as it is heavily fished in California to be used as a human food source.
Market squid, other squid species, and cephalopods in general are pretty amazing creatures. Sno-Isle Regional Library System has some good resources including the book Kraken by Wendy Williams and Super Suckers, The Giant Pacific Octopus and other Cephalopods of the Pacific Coast by James S. Cosgrove. Sno-Isle has also recently acquired Squid Empire, The Rise and Fall of the Cephalopods by Danna Staaf. I’m still on the waiting list for that one but it promises to be an enlightening read.
*This species has also been known under the scientific name Loligo opalescens.