What do jellyfish eat? Introduction to the main types of food for jellyfish

Jellyfish are important plankton in aquatic environments, a collective term for invertebrate animals of the class Scyphozoa in the phylum Cnidaria. There are many species with diverse forms, commonly found in oceans around the world. The vast majority are marine, with only a few species found in freshwater, and they are most abundant in the shallow waters of tropical and subtropical seas. Let's take a look below at what jellyfish eat!

What do jellyfish eat?

Jellyfish are all carnivorous animals, feeding on plankton, small crustaceans, polychaetes and even small fish. Although they look beautiful and gentle, they are actually very fierce, and once they encounter prey they never easily let it go. However, they have no respiratory organs or circulatory system, only primitive digestive organs, so captured food is immediately digested and absorbed in the gastrovascular cavity. After digestion, the nutrients rely on the beating of cilia on the walls of the ring canal to push the nutrients from the gastric cavity through the radial canals into the ring canal, then through the primary radial canals, interradial canals, gastric cavity and mouth to expel undigested food residue from the body.

Is a jellyfish sting poisonous?

A jellyfish sting is poisonous. The surface of jellyfish tentacles and tissue around the mouth has stinging cells, which contain nematocysts that store venom. They can fire nematocyst threads to inject venom into the bodies of humans or animals, producing various biological toxic effects on the cardiovascular system, blood, nerves and muscles. Jellyfish toxins have lethal activity, hemolytic activity, cardiovascular toxicity, liver toxicity, neurotoxicity and enzymatic activity, among others. After being stung, humans may experience rash, redness and swelling, itching, pain, decreased blood pressure, and even difficulty breathing, fainting, shock and death.

What types of jellyfish are there?

1. Box jellyfish: The entire bell of the box jellyfish is cube-shaped. They are distributed in tropical and subtropical shallow seas, with a few living a floating life in the open ocean. The stinging cells on their tentacles are highly toxic. Common representative species include the hand-drawn jellyfish and the box jellyfish.

2. Coronate jellyfish: The medusa of the coronate jellyfish is dome-shaped, conical, or flattened, but there is a constricting groove in the middle of the exumbrella that divides the bell into upper and lower parts, and the corresponding gastric pouches are also divided into upper and lower parts. They are mainly deep-sea species, such as the rimmed-leaf jellyfish.

3. Stauromedusae: Stauromedusae are scyphozoans that live a sessile life. The body is formed by the combination of the polyp form and the medusa form. They are often distributed in colder seawater, attached to seaweed. Examples include the trumpet jellyfish and the tall-cup jellyfish.

4. Semaeostomeae: The bell of Semaeostomeae is bowl-shaped or butterfly-shaped, and the bell margin has 8 to many notches, with tentacle pouches in the notches. The vast majority live in coastal waters. Common species include the moon jellyfish, the swimming jellyfish and the jellyfish.

5. Rhizostomeae: Rhizostomeae are close to Semaeostomeae. The mouth is not located in the middle of the body, but on the movable tentacles, and there is a small opening that can accept small food molecules in the water. Representative species include the jellyfish (Rhopilema esculentum) and the cannonball jellyfish.