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1. Shrimp Body Anatomy
The body of a shrimp, externally divided into two parts: the first part is the head and thorax fused into the cephalothorax, and the second part is the long, narrow abdomen.
The entire body of the shrimp is protected by a hard chitinous shell, with the carapace at the cephalothorax, often thicker and harder than other parts. The carapace usually encases the gills and most of the internal organs. Water is regularly pumped through the gills by the movement of mouth appendages. A sharp and rigid rostrum, possibly with multiple sharp spines, protrudes from the front of the carapace, called a rostrum, used for offense or defense and can help the shrimp maintain balance when swimming backward. Two protruding eyes on either side of the rostrum. They are compound eyes with panoramic vision and the ability to detect movement well; however, some blind shrimp species have adapted to their burrowed mud-dwelling environment.
Two pairs of antennae also protrude from the head of the carapace. One of these pairs is very long, possibly twice the length of the shrimp's body, and the other pair is short. The antennae serve as sensory organs for touch, smell, and taste. The long antennae help shrimp navigate their environment, while the short antennae assess the suitability of food or prey.
There are eight pairs of legs emerging from the cephalothorax. The first three pairs, scientifically called maxillipeds, are jaw legs used to bring food into the mouth and pump water through the gills. In the crangon crangon species, the first pair of legs, maxillula, pumps water through the gill chamber. The remaining five pairs, scientifically known as pereiopods, form the shrimp's ten walking legs. In the crangon crangon species, the first two pairs of walking legs have claws for capturing food and bringing it to the mouth or for fighting and self-grooming; the remaining three pairs, long and slender, are used for walking or perching.
2. Internal Organ Systems of Shrimp
The internal organ systems of shrimp can be divided into groups: the nervous system, digestive system, respiratory system, circulatory system, muscular system, reproductive system, and excretory system. The shrimp's nervous system includes pathways transmitting nerve signals from the eyes and antennae to the brain located near the eyes, the head of the carapace, and nerve cords spreading to the muscles, controlling movement, and other body parts, along an axis running below the shrimp's abdomen.
The digestive system of shrimp consists of a mouth located near the jaw legs, leading food into the stomach cavity, located just behind the brain inside the carapace and occupying a large volume inside the carapace. After digestion in the stomach, the digested food is pushed along the intestine, a small tube running along the upper part of the abdomen (running along the back), and waste material exits at the anus located at the shrimp's tail. The end of the stomach also has a tube connecting to the liver, located behind the stomach inside the carapace, where nutrients can be stored.
The respiratory system has gills located on both sides of the carapace, inside the carapace, near the jaw legs. In some species, gills also appear on the swimming legs. Water is regularly flowed through the gills to provide oxygen and remove carbon dioxide due to the movement of some jaw legs and swimming legs with gills located near the swimming legs.
The circulatory system consists of the heart located behind the liver inside the carapace and near the junction with the abdomen, pumping blood, transporting nutrients from the liver and stomach, and carrying oxygen from the respiratory system, to other body parts through blood vessels, including blood vessels running along the upper part of the abdomen (running along the back) parallel to the intestine, and blood vessels running down below inside the carapace, and may also have blood vessels running along the lower part of the abdomen, blood vessels going to the head.
The muscular system includes small muscles in the legs and antennae, moving the legs and antennae, and a large muscle in the abdomen, occupying most of the volume of the abdomen, moving the abdomen and tail.
The reproductive system, in male shrimp, consists of testes located below the heart and sperm ducts leading sperm down to openings at the base of the fifth walking leg; in female shrimp, it is egg sacs below the heart and egg ducts leading eggs down to openings at the base of the third walking leg. After mating between male and female shrimp, fertilized eggs adhere to the undersides of the swimming legs of female shrimp, except for pan-fried shrimp that do not embrace eggs with swimming legs.
The excretory system includes kidneys, a bladder, and a urethra leading waste out, all located next to each other and at the head of the shrimp, inside the carapace, and in front of the mouth.
13. Land crayfish is a harmful species to most aquatic organisms
Land crayfish eat all aquatic organisms, competing for food sources with native species, causing characteristic shrimp and fish to disappear. Land crayfish, also known as red crayfish, crawfish (scientific name Cherax quadricarinatus), is a dangerous invasive species. This species moves quickly on the bottom of ponds, streams, prefers digging burrows, has the ability to reproduce rapidly, and withstand environmental changes.
With large, healthy red claws, they can cut through tough plant stems, eat all types of young plants, and even small shrimp and fish. They also dig deep burrows for shelter and can damage the ground or cause erosion in rivers and streams.
Adapting well to the environment makes them harmful invasive creatures when spreading shrimp fungal disease, white spot virus to shrimp, and some parasitic species. Living in a favorable natural environment, the lifespan of a land crayfish can reach up to 30 years. Moreover, their resilience increases as they can regenerate limbs or even survive if they are severed in battles.
More dangerously, if consumed raw, humans can be attacked by a dangerous type of worm that invades the lungs. This parasite, named Paragonimus kellicotti, causes a rare infection called paragonimiasis and has been found in the lungs of 6 victims who consumed land crayfish living in the Missouri River, USA, according to doctors at Washington University School of Medicine in St. Louis.
In addition, the Centers for Disease Control and Prevention in the US Department of Health and Human Services also stated that each year in the US, there are up to 80,000 cases and 100 deaths due to Vibrio infection, a bacteria parasitic on the shells of animals. Many studies have found high concentrations of mercury as well as other toxic chemicals such as DDT, PCBs, dioxins... are related to cancer, nervous system disorders, and other diseases.
14. Shrimp species create distant echoing sounds up to 3km
European spiny lobster, one of the most expensive seafood in the world, produces loud sounds to communicate with each other or repel prey. The leading research group, led by Dr. Youenn Jézéquel at the European Marine Research Institute, recorded over 1,500 sounds produced by 24 European spiny lobsters (Palinurus elephas) in the Gulf of Saint Anne du Portzic, France. They used underwater headphones placed at distances ranging from 0.5 to 100 m from the lobsters.
The sounds created by the smallest lobster group could only be recorded at distances of about 50 m or less. However, larger lobsters in the study produced sounds that could be detected from distances of about 100 m. By examining the sound intensity at different distances and considering high noise levels in the water environment in the gulf, scientists estimate that the sound produced by European spiny lobsters by rubbing their antennae together can travel further, reaching a distance of over 3km with individuals measuring 13 cm long.
European spiny lobster is among the most expensive seafood in the world, with prices ranging from 44 to 132 USD per kilogram. However, decades of overfishing have contributed to a significant decline in the population of this species since the 1970s. European spiny lobster is classified as vulnerable in the International Union for Conservation of Nature (IUCN) Red List. They inhabit the seas off the coast of England, Ireland, and the Mediterranean, at depths of about 198 m.
The research results have significant implications for conservation efforts. The use of non-invasive techniques such as underwater sound can play a crucial role in monitoring and surveying European spiny lobsters in coastal areas.
