“The Monsters of the Sea” Excerpt
Their rock-star feature is, of course, their tentacles: the big bad boys that prove the cnidarian is not just a pretty face. And though they have no brain, they do have a network of neurons (called a nerve net) on their outer layer that allows them to sense their environment.
Some of them have eyes that respond to visual stimuli, but it is still unknown to scientists as to how they can process what they are “seeing” without a brain. The detection of their surroundings comes from rudimentary sensory nerves, called ocelli, at the base of their tentacles that can locate the presence and absence of light.
The smallest of the species can be as minuscule as an inch, but the bell of others can reach up to seven feet across and the tentacles up to 100 feet long. Their makeup is very basic, comprised of an epidermis—the outermost layer; the gastrodermis—the innermost layer; and the mesoglea—the “middle jelly” that separates the epidermis and gastrodermis and gives cnidaria their name.
They also have two multi-tasking organs, one of which takes care of both eating (functioning as a mouth) and… disposing, which is pretty gross, I know. But they are dealing with limited real estate. This first organ is plainly and appropriately called the orifice. Their second multi-tasking organ is the gastrovascular cavity, which functions as a gullet, stomach and intestine.
Jellyfish are made up of roughly 98 percent water, which is why they are mostly see-through and why they disintegrate on land. Their life is short, spanning from three to six months, but at least they look good.
A large pack is called a bloom—what a beautiful name for a cloud of colorful, floating blobs. Like a bouquet of sea flowers. And thanks to humans, the species is thriving. But their overpopulation can reap not-so-pretty results, and has been known not only to put a damper on swimming season but also to jam up machinery at coastal power plants, causing power outages. They have threatened fish hatchery populations by eating fish larvae, and their abundant presence can even change water chemistry.
They are carnivores. The smallest jellyfish eat algae and zooplankton, while those who can handle a heartier meal enjoy shellfish and larger fish. But while their stingers and transparency are a highly effective defense, they do have some predators. Fish, sea turtles, crustaceans and even others of the same species will, in return, dine on them if they get the chance, and when approached at their bell, jellyfish are fairly defenseless.
