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Part of what I like about writing this column is that I get to research subjects I don’t know about, or at least don’t know enough about. Despite writing more than 200 columns during the last 10 years or so, it has never been difficult to find a topic. My favorite way to land on a topic is to be introduced to it by a reader of my writing. A recent inquiry from a reader was particularly timely following last month’s column about bioluminescent creatures. She asked for help identifying eggs that came from a bioluminescent creature — a squid. Squid eggs are found in little, finger-like sacs that are attached in the center. They look a bit like an anemone — a form that made it clear what they were.
What I wasn’t sure about was how squid reproduce and why the eggs end up in these little sacs. Most animals in the ocean reproduce through a process known as spawning, in which sperm and eggs are released into the water. Sometimes the eggs are free-floating and other times they are attached to some type of surface. Either way, the fertilization takes place externally (outside of the animal’s body). This happens in many types of ocean animals, from bony fish to invertebrates like corals and shellfish. Squid, however, are rare in their method of reproduction. They reproduce internally. They have highly specialized behaviors and adaptations that facilitate this method and are as odd as the creatures themselves.
The behavioral component is particularly fascinating, as it involves a series of elaborate movements and color changes, as well as occasional battles. Because fertilization takes place internally, males have to compete for “access” to a female. They sometimes do this by displaying warning coloration in an attempt to scare other males away. If another male does approach, the male squid can use a number of body parts to stake his claim, including a sharp “beak” tucked away inside the center of the tentacles. It also has sharp hooks on some of its tentacles that it typically uses to capture prey, but can use to battle opponents. The male then uses a specialized “arm” to deposit a sperm packet inside the female. This arm is different from its other arms in that, rather than a suction cup, it ends in a spoon-shaped tip designed to transfer the sperm packet.
Once the eggs are fertilized, the female lays them inside a series of small, jelly-like noodles. This coating helps protect them as they develop. Inside, there are thousands of little eggs that each have their own yolk to fuel their development. They start out by developing tiny organs, but then an amazing transformation happens. They become able to change color while still inside their egg sacs. I have only seen this on video, but it is well worth looking up! I have, however, seen a tiny larval squid in a tide pool at Potts Point with my daughters when they were young. I had the rare experience of seeing its color change against my daughter’s pink hand — the world’s tiniest tide pool.
Little did I know then that I would later learn, thanks to a curious reader, about the oddities of squid reproduction, and that the color change I observed might someday be used to scare away a male competitor in the process of “courting” a female squid. There is always something new to learn and more questions to ask that help me better appreciate and understand how lucky we are to have the diversity of ocean creatures we have right here on our Maine coast.
