It is estimated that many friends have watched the cartoon "SpongeBob SquarePants", in which the protagonist is a talking starfish who always loves to break into trouble. Looking at its cute and cute appearance, it is really impossible to equate it with the fierce predator. However, it is these stupid-looking starfish, some of which are specialized in shellfish products, which have recently caused headaches for fishermen in Jiaozhou Bay in China.
< h1 class="pgc-h-arrow-right" > first look at the basic situation of starfish</h1>
Starfish is actually a general term for a wide variety of echinoderms, which mainly have a single order, namely the order Officiae, Echinosta, and Pincer, and there are about 1600 species in the world, almost all over the major oceans, especially in the Pacific Ocean. Different types of starfish vary greatly, with the largest reaching nearly 1 meter and the smaller reaching only 2-3 centimeters.
Although there are many types of starfish, there are many similarities in form and living habits. For example, in terms of body structure, the body of starfish is flattened, and on the flat body disc, there are usually five symmetrically radially growing brachiopods, which are named "starfish" because of the shape of the body similar to five stars.
Don't look at the starfish looks very soft, but inside the body, there are bone plate structures formed by many calcareous bones, which are connected together by connective tissue, so they have both free mobility and strong toughness. The bones inside the body extend to the surface of the body, forming spinous protrusions, and in the middle of the protrusions and bone plates, a gill organ is formed, which has the function of breathing and excreting metabolites.
The outer part of the starfish brachiopod is also covered by a relatively hard spiny package, hollow inside, which is distributed in rows of tube feet, and some species have suction cups at the ends of the brachiopods. The functions of the starfish tube foot can be described as very powerful, such as catching prey, climbing objects, swimming in the water, etc., all need to be achieved with the help of the tube foot.
In terms of living habits, starfish belong to the typical carnivorous animals, although their nervous system is not developed, but the receptors on the spinous shell are very sensitive, can accurately feel the content of various chemicals from the surrounding seawater, so as to be able to identify potential food sources around. Starfish inhabit the coastal sandy bottom mud, soft bottom mud and other seabeds, as well as coral reefs and other areas.
According to the different objects of starfish hunting, the world's starfish can be roughly divided into three feeding methods, one is the deep-sea starfish, generally small, mainly to capture microorganisms, organism residues and so on. The second is the starfish without suction cups on the tube feet, which have limited mobility and are smaller, feeding mainly on smaller crustacean marine organisms. The third species is the most numerous, larger, with suction cups on the tube feet, with strong autonomous predation ability, and the food is mainly bivalve (such as clams, sea oysters, abalone, scallops, etc.) marine animals. The starfish that erupted in Jiaozhou Bay, Qingdao, is the third type mentioned above.
<h1 class= "pgc-h-arrow-right" > starfish's "skill" in preying on bivalves</h1>
In the past 10 years, many seas in the world have been invaded by starfish. For example, since 2006, the coastal areas in the north of China have concentrated on the flooding of starfish every few years, such as Jiaozhou Bay, Laoshan and other places, and there are almost hundreds of them distributed per cubic meter of seawater. In 2007, almost half of the Philippines' more than 20,000 square kilometers of coral reefs were invaded by the "starfish army." Many of the seafood products raised by fishermen have been greatly damaged by the crazy predation of starfish.
The starfish that invaded the northern waters such as Jiaozhou Bay in China is actually a very large and relatively common species - multi-spiny sea disc car, this type of starfish has five radial brachiopods, spoke diameter of about 15 cm, each brachiopod has four rows of dense tube feet, and the end of the tube foot has suction cups, which makes them very powerful in catching shellfish prey and clinging to objects in the sea.
The food of the spiny sea pan car is mainly clams, abalone, scallops, sea oysters and other shellfish, widely distributed in China's Yellow Sea and Bohai Sea, only in the Jiaozhou Bay outbreak year caused by the loss, reached tens of millions of yuan.
The methods used by spiny sea disc carts when hunting prey can be described as eye-opening, they do not have a huge bite force, no sharp teeth and claws, even we humans are difficult to break open with our bare hands, shellfish, but they have their own set of methods.
First, the sensitive receptors on the surface of the body are used to capture the "breath" of the prey, and then the tube foot is used to hold the prey tightly. Because their hunting objects are usually weak and powerless animals such as bivalves, abalones, sea urchins and so on in the ocean, once they are held by the tube foot of the starfish, there is no chance of escaping.
Next, the starfish's patience to "stalk" is on the line, and when they hold this food, they will do nothing at first, but just cling to it tightly, using hours or even days to slowly consume the physical strength of their prey. In this process, the soft body will also be used to cooperate with the tube foot, tightly wrapping the prey, so that the prey is in a state of hypoxia for a long time.
After that, if the prey is physically weak or the shell is loose, the starfish will immediately seize this opportunity, on the one hand, inject hormones into the shell, so that the closed muscle of the shell fails, on the other hand, it will spit the spray door stomach in its own body into the shell, and then secrete digestive enzymes, so that the body inside the prey will soften and decompose, until the shell is all open, and then the starfish will swallow all the food into the stomach to complete the final digestion.
<h1 class="pgc-h-arrow-right" > why are starfish so harmful to shellfish? </h1>
On the one hand, in a very suitable marine environment (temperature, abundance of food sources, etc.), starfish have very strong fertility. The vast majority of starfish are hermaphrodites, with as many as a few or even a dozen reproductive glands, and female adults generally lay very large eggs, excreting 2.5 million grains at a time. Male adult individuals have testicles growing on each brachiopod that can discharge sperm directly into seawater, where eggs and sperm meet to complete fertilization and development.
Second, starfish have a longer lifespan. Most starfish have a lifespan of about 10 years, and some species can reach more than 30 years, of which the time from juvenile development to sexual maturity is not long, usually within 2 years, which undoubtedly greatly increases the population of starfish.
Third, starfish have a very anti-heavenly regenerative ability. Even if the starfish suffers damage from the outside world, as long as it is not too serious damage, it can repair itself. For example, after a broken wrist, it can grow again, and the function is exactly the same as before. Some species of starfish, even after cutting off the brachiopods, only have a part of the middle of the basal disk on the brachiopods, then they will re-develop into a new starfish individual.
Fourth, starfish "waste of food" is serious. Due to the lack of space in the body of starfish, its digestive system is not well developed, especially the intestine is compressed to a very short point, and the digestion of food swallowed into the body is very poor. According to research, starfish can only digest 6 grams of food at most when they eat 100 grams, and the rest can only be excreted from the body. Therefore, in order to maintain the energy intake requirements, starfish must eat a lot of food, and most of these foods are "invalid inputs", and the waste is very obvious.
<h1 class="pgc-h-arrow-right" > can people eat the problem? </h1>
For Jiaozhou Bay and other thorny seas in the northern waters of Our country, it is indeed a kind of edible starfish, so there is no shortage of cooking methods practiced by foodies on the market, such as roasting starfish, steaming starfish, boiling starfish soup, etc., but because there are not many parts of starfish's body that can be eaten by people (mainly reproductive glands), and starfish also contains ingredients that are slightly toxic to the human body, so it is certainly not advisable to eat a large number and regularly.
Of course, there are other ways to control the number of starfish and make them better serve human beings, for example, by cultivating starfish's natural enemies (such as snails), or creating a more relaxed living environment for natural enemies (such as Haiou, etc.), using this "life-and-death" approach to starfish is a very environmentally friendly countermeasure.
In addition, biological products (such as vitamins, fats, trace elements, proteins) for starfish beneficial extracts can be developed to increase the added value of their products to meet the medicinal and health care needs of different populations. Of course, the way to capture starfish, do not use chemicals and large-scale trawling mode of action, so that although a large number of large amounts can be captured in a short period of time, it will also accidentally injure or kill other marine organisms, and at the same time it will cause regional seabed pollutant disturbances, trigger regional biological migration or population reduction and other issues, not only can not fundamentally solve the problem, but also will "self-damage eight hundred", more than worth the loss.