Jellyfish, wonders of the sea that they are, have no skeletons, "no digestive tract, no brain, no nervous system, no respiratory system, no circulatory system and no eyes," as the Daily Herald once incredulously reported. Despite this, they're somehow still able to swim around and generally function all while also being 95 percent water, per Daily JSTOR. But, how do jellyfish eat if they don't have digestive systems?
Is the 5 percent of them that isn't water doing all the work to keep them fed?
With 4,000 different types of jellyfish, not all of them do things the exact same way. But, for the most part, they eat using their long tentacles, which sting and entrap prey.
The Daily Herald further elaborated on this super skilled tactic, reporting, "Once stung, these creatures become tangled in the stringy tentacles. These simple jellies sense or smell the wounded prey, which triggers an automatic reaction that pushes the prey-entwined tentacles toward the mouth."
Don't we all wish our arms could sense food near us and automatically put it in our mouths?
But, one study has some scientists suggesting that jellyfish are more calculated about hunting than that. According to Phys.org, Irukandji box jellyfish are believed to actually use their tentacles to fish for food.
The study found the jellyfish would twitch and light up parts of their tentacles to lure fish in.
via GIPHY/James Cook University
"They're not opportunistically grazing — they're deliberately fishing. They're targeting and catching fish that are at times as big as they are," study author Robert Courtney said. "This is a really neat animal that is displaying a surprisingly complex prey capture strategy."
You can see that twitching strategy closer below:
via GiPHY/James Cook University
Whether jellyfish happen to bump into food, or draw it to them, one thing is true: All that food has to go somewhere. And, in the case of the jellyfish, not having a complex body system means that ...
Their mouths are also their butts.
Sorry, but it had to be said. You came here to learn how jellyfish eat, and you needed to learn that jellyfish also poop out of the same hole they eat with. As JSTOR reported, it's simply part of the natural cycle that comes with having 5 percent meaningful body parts.