What do jellyfish eat? A detailed explanation of the feeding characteristics of jellyfish
Jellyfish is the collective name for the genus Rhopilema in the family Rhizostomatidae, class Scyphozoa. They live a floating life in the ocean. The adult umbrella is raised and hemispherical in shape, with a smooth surface and a thick mesoglea. They are widely distributed along the coast of China, most abundantly along the coasts of Zhejiang and Fujian. From August to September each year they appear in groups on the sea surface and can be artificially bred. Let us now take a look at what jellyfish eat!
What do jellyfish eat
Jellyfish do not feed during the planula larva stage. They begin feeding only when they metamorphose into the 4-tentacle scyphistoma larva. The tentacles are the predatory organs, feeding on small zooplankton. The ephyra larva has one square mouth and feeds on small plankton. As it grows and develops, the oral arms form. When it reaches an umbrella diameter of about 20 mm, the central mouth closes, and it becomes a young jellyfish. From the young jellyfish stage to the adult stage, feeding is carried out through the many suction mouths that appear on the oral arms and shoulder plates, feeding on small zooplankton. The diet includes many types of prey, mainly copepods, cladocerans, ostracods, cumaceans, amphipods, ciliates, bivalve larvae and the larvae of other zooplankton.
Can jellyfish sting people to death?
Jellyfish can sting people to death. The thin and tender parts of human skin are most easily stung. Generally, an electric-shock-like stinging pain appears within a few minutes, and after a few hours the injured area gradually develops linear rows of red-spotted blood rash, with itching and burning pain. Mild cases can heal on their own in about 20 days. In highly sensitive patients, redness and swelling, wheals, blisters, ecchymosis, and even epidermal necrosis may appear locally. Systemic symptoms may include restlessness, chills, abdominal pain, diarrhea, listlessness, and chest tightness and shortness of breath. In severe cases, there is often coughing and wheezing, expectoration of white or pink frothy sputum, accompanied by rapid and weak pulse, cyanosis of the skin, and falling blood pressure and other signs of anaphylactic shock. If rescue is not timely, such sting patients can die within a short time.
Variety classification of jellyfish
1. Yellow-spotted jellyfish: The yellow-spotted jellyfish is very similar to the jellyfish. The main differences are that the outer umbrella surface has many short, small, pointed and hard wart-like protrusions, and yellow-brown spots, and each 1/8 of the umbrella margin has 8 long oval marginal lappets. The club-shaped appendages borne on the oral arms are relatively short and small, and the ends of the appendages are spherical or club-shaped. The gonads are very large, oval in shape, and the base surface has spiny protrusions. The adult is milky white, and many small yellow spots are scattered on the outer umbrella surface. This species is a tropical type, mostly distributed along the southern coasts such as Fujian and Guangdong.
2. Club-shaped jellyfish: The club-shaped jellyfish is relatively small, with an umbrella diameter of 40-100 mm and an umbrella height of 50 mm. The outer umbrella is very smooth and very thin. At each 1/8 of the umbrella margin there are 14-16 slightly round and flat marginal lappets. There are no gonads, and the shoulder plates are very small. The manubrium is particularly short, the oral arms are about 35 mm long, the base is 3 mm, and the oral disc diameter is 12 mm. The club-shaped appendages borne on the oral arms are relatively sparse, and the terminal club-shaped appendages are about 10-12 mm long. The filamentous appendages are not well developed and are borne only on the shoulder plates. The ring canal is not well developed, the inner ring mesh system is wide and obvious, and the inner outline is roughly parallel to the gastric cavity. The sensory canals branch or form a network. In China it is distributed only in the sea area around Xiamen.
3. Sand jellyfish: The sand jellyfish is a large jellyfish, with an umbrella diameter of 180-980 mm, hemispherical in shape, and the outer umbrella surface densely covered with fine small granules. The number of marginal lappets varies considerably, usually 14 at each 1/8 of the umbrella margin. There are 8 sensory organs. There are 16 radial canals, and the ends branch and connect to each other to form a network. The inner umbrella has well-developed circular muscle. There are 8 oral arms, with the bases fused, and the free ends spread outward, with the ends bifurcating in two, and the side branches long. The oral arms bear many filamentous appendages. There are 4 separate subgenital pits and no genital papillae. When alive, the umbrella is brown and the appendages are dark brown. It is a cold-water-preferring species, mainly distributed in the southern Yellow Sea and northern East China Sea in China.
4. Box jellyfish: The box jellyfish is also called the sea wasp, etc. It mainly lives in the coastal waters of northern Australia and New Guinea, the Philippines and Vietnam, and is named for its slightly round shape, which resembles a square needle. It is venomous. If a person touches its tentacles, they will soon die. It is considered the most lethal jellyfish, bar none.