Sea urchin is a class of echinoderms, which is a kind of invertebrate animal living in shallow waters of the ocean. The main features of sea urchins are their spherical, disc-shaped or heart-shaped bodies without arms, and their fused internal skeleton. The digestive tract is long and coiled inside the body, feeding on algae, water fleas, and worms. Most sea urchins are dark in color, such as green, olive, brown, purple, and black. They mostly live on the seafloor, preferring to inhabit reef forests in the subtidal zone below algae-rich areas or crevices between rocks, as well as hard sandy shallow areas in the sea, with the characteristics of avoiding light and hiding during the day and coming out at night. Sea urchins have a wide range of food sources. Carnivores feed on worms, mollusks, or other echinoderms on the seafloor, while herbivores mainly eat algae. In addition, there are sea urchins that feed on organic debris and animal corpses. Most sea urchins are dioecious, and individuals take 1-2 years to reach sexual maturity through the development of sea urchin larvae (long arms). Sea urchins are the earliest model organisms used in the history of biological science. Their eggs and embryos have played a crucial role in the development of early developmental biology and are one of the longest-lived marine organisms on Earth. The main features of sea urchins are their spherical, disc-shaped or heart-shaped bodies without arms, and their fused internal skeleton. The digestive tract is long and coiled inside the body, feeding on algae, water fleas, and worms. Most sea urchins are dark in color, such as green, olive, brown, purple, and black.
Sea urchin is an ancient creature in the ocean, closely related to starfish and sea cucumbers. According to scientific research, they have existed on Earth for hundreds of millions of years. In the distant Paleozoic and Mesozoic eras, there were many species of sea urchins, and up to 5000 species of sea urchin fossils have been discovered. Due to the changes in the sea, fossilized sea urchins have even been found in the Tibetan Plateau in China. Many extinct species are iconic fossils from the Paleozoic and Mesozoic eras.
Sea urchins are suitable for feeding enthusiasts of fish. Sea urchins are naturally timid and have a gentle nature. The larvae of sea urchins are called juvenile sea urchins after metamorphosis. When they reach a certain level of growth, they need to be transferred to net cages. However, because the juvenile sea urchins are relatively small, artificial methods are generally used for cultivation.
1. Sliding bacterial disease
It can infect various sea urchins of different sizes, especially in temperatures above 16°C, particularly in summer.
Pathogen: Quarnant Bacterium.
Symptoms: Detachment of attached side (ventral surface) epidermis, whitening and discoloration around the mouth, black-green color around and in the mouth, lighter color and elongation of tube feet; shedding of spines is not obvious, and the appearance is similar to that of a healthy individual when viewed from the back. Microscopic examination reveals that there are 20-60 microns long bacteria agglomerating and sliding on the surface of tube feet.
Prevention and control:
(1) Reduce stocking density and increase water exchange.
(2) Spray 0.6g/m3 of Eel Net throughout the entire tank.
(3) Mix Fish Health No. 1 at 1% concentration into the feed and feed continuously for 5 days.
2. Spine shedding disease
The disease occurs when the water temperature is below 16°C, and it spreads rapidly with a mortality rate of over 80%, and can infect various sea urchins of different sizes, often leading to their death.
Pathogen: Unknown, possibly bacteria.
Symptoms: Black spots can be seen on the shell surface, spines become paler in color, slanting like withered branches and easily falling off upon touch. There is a decrease in the number of tube feet, weak adhesion, and diseased individuals often fall from attached objects to the bottom of the tank.
Prevention and control: There are currently no effective drugs for treatment, however, when the water temperature is raised above 16°C, the diseased sea urchins can recover on their own.
1. Preparation: In the process of domesticating sea urchins, it is necessary to prepare a suitable-sized fish tank for them. Then, a layer of fine sand should be placed at the bottom, followed by planting seaweed and pouring in clear, unpolluted, and high-salinity water to promote the healthy growth of sea urchins.
2. Feeding management: During the process of raising sea urchins, it is necessary to feed them mainly with seaweed and other algae, or feed them with sardines to encourage their growth. Pay attention to the amount of feed, which should be determined based on the species and size of the sea urchins. Generally, feed should be given every two days.
3. Strengthening management: When farming sea urchins, it is necessary to regularly check the cleanliness of the water and the growth of the sea urchins. If the water becomes turbid or has a strange odor, it should be replaced in a timely manner. The fish tank should also be cleaned and disinfected to prevent the sea urchins from getting infected with pathogens, which is not conducive to their growth.
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