I have something to admit: I think mammals are the coolest. I just really like mammals, with birds as a close second. But I really want to make sure that I give all cool animals their due, so I’ve been trying to make sure I mix in some non-mammalian or non-avian species on this blog.
With that in mind, I bring to you today a pretty smart invertebrate: the Japanese flying squid (Todarodes pacificus). Or more accurately, a brief survey of squid in general with a slightly more specific focus on Japanese flying squid at the end because they (you guessed it) fly. Or at least glide and fall with style. Take a seat and learn how it’s done.
What are squid
Starting with the basics: what are squid? Squid are cephalopods and are part of the animal class Cephalopoda. Other types of cephalopods include octopus, cuttlefish, and nautilus. Cephalopods are exclusively marine animals and cannot be found in fresh water.
Like all other cephalopods, squid contain bilateral symmetry, which means you can cut them down the middle and end up with mirror image right and left halves. They also have a distinct head and a mantle (the bit of a squid’s body that contains all the organs).
Squid are pretty soft, texturally speaking, but they do have a small, rod-like internal skeleton made of chitin. Squid also have 8 sets of arms, with 2 additional tentacles around the mouth.
How squid work
Let’s start by talking about the squid nervous system. Cephalopods in general have one of the most highly developed nervous systems among invertebrates. Squid have a brain that looks like a donut: it’s a ring of nerves that surrounds their esophagus. This highly developed brain has made squid pretty smart (although they are thought to be less clever than octopuses and cuttlefish). Caribbean reef squid can communicate messages for specific individuals by changing the color patterns on their body. Another species, the Humboldt squid, works cooperatively in groups to bring down prey. Some researchers even think that squid are about as intelligent as dogs.
Squid, like all other cephalopods, are predators. They have a sharp beak in their mouth that kills and tears their prey. (The tearing bit is pretty important, since, remember, the prey has to be small enough to go through the esophagus which is surrounded by their brain. Don’t want to get brain damage by trying to swallow something that’s too big). To hunt, squid locate their prey by sight or by touch and then grab it with their tentacles. Hooks and suckers on the surface of the tentacles keep the prey from getting away.
You can separate squid into males and females. Male squid take a bunch of sperm and roll them into a bundle called a spermatophore. This spermatophore is placed inside the mantle of the female squid: in deep-water squid, this is may be done by a long penis that can reach the female. In shallow-water species like the Japanese flying squid, the spermatophore is removed from the penis and placed in the female by a special tentacle that is adapted to store and transfer spermatophores. This tentacle is called the hectocotylus. Once in the female, the sperm can be stored until it is time to fertilize the eggs. Both males and females die soon after mating: males after transferring the spermatophores and females after the eggs are laid.
I believe I can fly
All of the squid knowledge you just learned applies to Japanese flying squid. More specific facts: these squid can grow to about 20 inches long and weigh less than a pound. They can be found in both the Pacific and Atlantic Oceans and generally live in the upper layer of the water.
Now the fun part: how they fly. Japanese flying squid travel through the water using jet propulsion. They suck water into their mantle and then shoot it out of their body (I should note that other squid and some octopuses do this too). Japanese flying squid will use this propulsion to shoot themselves into the air. This may actually help the squid move faster while also using less energy. One team of researchers estimated that some species of squid can move 5 times faster in the air than in the water. Once the squid are in the air, they aren’t using any more energy and can just coast. Japanese flying squid can fly pretty far and have been recorded flying almost 100 feet.
Squid on the menu
Japanese flying squid play an important role in commercial fishing, as they are caught both for consumption and to be used as bait for other fish. They are a very popular snack in Japan, China, and Korea, and often end up as a part of sushi.
Unlike other animals I talk about here, we aren’t super concerned with the conservation status of Japanese flying squid. Although they are often targeted by fishing, there are ways to capture them that protects the population. Remember, Japanese flying squid (like other squid) die soon after mating; by trying to catch them after males have released their spermatophores and females have laid the eggs, we don’t have to worry so much about damaging the overall population. Of course, we should still be vigilant and make sure we don’t overhunt the squid.
But a word of caution: squid are not always an easy snack. One woman ended up in a case report of the Journal of Parasitology after eating a Japanese flying squid in 2012.
Here’s what happened. One day, a 63-year-old Korean woman was preparing Japanese flying squid to eat. Raw squid is a popular snack in Korea, so she simply took a whole live squid and parboiled it for a few seconds. Then, she popped a small piece in her mouth to see how it tasted.
This did not go as expected. The woman immediately felt sharp pain in her mouth and experienced what felt like “bugs” biting into her cheek. Despite spitting the squid out, she still felt like there were small, squirming bugs going into her cheek.
The emergency department extracted “twelve, small, spindle-shaped white organisms, 2-5mm in length” from her tongue, cheek, and gums. The physicians initially thought that these things were some sort of squid parasite since they were still squirming around. But when they looked closer at the organisms, they realize that they were not parasites but were in fact spermatophores and sperm bags. It seems that the bit of squid the woman started chewing contained spermatophores; when she started chewing, the sperm bags were released, and both the spermatophores and the sperm bags ended up getting stuck on the flesh of her mouth.
Is this unlikely to happen? Sure, as long as you properly prepare your squid before eating it. Either remove the internal organs (if you’re eating raw squid) or boil it long enough to kill the sperm bags. You can also protect yourself from parasites in raw squid or fish by freezing them before consumption.
So yeah, it’s very unlikely to have a squid spermatophores get embedded in your cheek. But the fact that it happened once still makes me pause for a moment before ordering squid for dinner.