Prawn Fish

The huge river prawn was one of the earliest shrimp subspecies discovered by scientists. A prawn is a small aquatic crustacean with an exoskeleton and 10 legs that belong to the Decapoda order, some of which can be eaten. Large swimming crustaceans or shrimp, especially those with commercial significance in the fishing sector, are referred to as prawns in the United Kingdom, Ireland, and Commonwealth countries. 

Shrimp in this group often belong to the Dendrobranchiata suborder. In North America, the word is more commonly applied to freshwater shrimp. The phrases "shrimp" and "prawn" aren't scientifically defined. The definitions of shrimp and prawn have evolved throughout time, and the terms are now almost synonymous. 


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About Prawns


Characteristics

Features

Kingdom

Animalia

Phylum

Arthropoda

Order

Decapoda

Family

Dendrobranchiata

Scientific Name

Dendrobranchiata

Common Name

Prawn 

Life Span 

2 to 4 years

Physical features

Has a shell skin type 

Natural Habitat

In the rocky areas of the coastal waters

Water type

Saltwater with an optimum pH of 6.5 to 9.0

Diet

Omnivore

Prey

Fish mainly Fresh fish, Brackish fish, Saltfish, plankton and insects 


Different Species and Types of Prawns

Macrobrachium rosenbergii is the scientific name for this subspecies. It can be found in both subtropical and tropical waters. Macrobrachium rosenbergii can be found all throughout the Indo-Pacific. Despite the fact that the majority of these subspecies reside in freshwater, some live in saltwater river mouths.

The Palaemon prawn can be found in ponds, rivers, and streams in Pakistan, India, and Bangladesh. The word prawn was first used in England in the 15th century. The animal was known as prane, prayne, or praine during the time. The terms shrimp and prawn fish are most commonly used in Ireland and the United Kingdom nowadays. The popular different types of prawns are Crevettes, Langoustine, tiger prawns, easy-peel prawns, brown shrimp, cocktail prawns etc. 


Differences and Similarities Between A Shrimp and A Prawn Fish

  • The distinctions between prawns and shrimps are often misunderstood. They are not the same animal, despite popular belief in some regions of the world. They both have an exoskeleton and ten legs, which is something they have in common. They both have similar appearances and reside near the ocean's bottom. Freshwater and saltwater are both home to the pawn and the shrimp. Prawns, on the other hand, prefer freshwater. Shrimp prefer to live in seawater. Their gills are also shaped differently, which is another difference. A prawn's body is fully straight, whereas a shrimp is slightly curved. 

  • By examining their legs, one can identify the difference between a shrimp and a prawn. The front legs of a shrimp are the largest. The prawn's second set of legs is the largest. Prawns have three pairs of legs, each of which has claws. Another distinction is that shrimp carry their fertilised eggs under their bodies until the babies are born, but prawns let their fertilised eggs grow in the water.


Behavioural Characteristic Features of Prawns

  • Physical characteristics- Prawns come in a variety of colours, including black, pink, white, and grey. When fully grown, a Palaemon prawn measure between six and eight inches long. The fish exhibits a faint blue colour when captured. Its body is elongated and cylindrical. The prawn's body is squashed slightly from one side to the other. 

  • Location- Banana, brown tiger, and western king prawn fish all live in the northern regions. They are larger in these areas than in other parts of the world and prefer to reside near the shore in coastal waters. Banana and tiger prawns can be found in Australia's northern regions. Exmouth, a town in England, is known for its banana prawns. Shark Bay is home to Tiger Prawns. King Prawn fish can be found throughout the coast of Western Australia. They can also be found in the Swan River in Australia. 

  • Palaemon Prawn fish- The body of a Palaemon prawn is divided into two sections. There are two parts and the one is anterior and the other is posterior. It has an unjointed cephalothorax that is the prawn has six pairs of appendages or body parts that are linked to the main body section. Those sections of a prawn lack joint, which humans have in their knees to help them bend. A Palaemon prawn's posterior has a jointed abdomen, which is the polar opposite of its anterior. The prawn's abdomen protrudes from the rest of its body. The abdomen of a prawn is divided into six sections. Each of the six segments has its own set of appendages. The appendages are found on the ventral surface, which is the prawn's lower body. One section of the prawn's abdomen is on the inside, while the other is on the outside. A telson can be found on the outside. The telson is found on the tail of the shrimp. The cephalothorax is located at the opposite end of the abdomen. The prawn's head meets its thorax at this point. The abdomen and neck form a protective barrier around the thorax. The shrimp has thirteen pairs of appendages at the bottom of its body.

  • Body of the Prawn- A prawn's colour can change according to the circumstances. They are able to do so because of the pigment in their skin, which is positioned right underneath their shell. They can turn blue, yellow, red, yellow-white, and sepia-brown thanks to the cells in their skin. The amount of that hue's cells in their body determines what hue they turn. School prawns get pale spots, but deepwater prawns get bright crimson or even scarlet spots as a result of the cells. Because of their location in the ocean, deepwater prawns turn vivid crimson. Because the colour isn't seen, they appear black. Predators will have a tougher time spotting them as a result.


Life Cycle of the Prawn

Prawns have a two- to three-year lifespan. They reach sexual maturity at the age of six to eight months and spawn in offshore waters. King prawns spawn all year, but tiger prawns spawn primarily in the spring and summer. In any given year, a single prawn can spawn many times. Hundreds of thousands of eggs are released by the female. 

The life cycle of a prawn is rather short. School prawns have a one-year lifespan on average. Eastern King prawns and other larger prawns have a two-year lifespan. They may even live for three years in rare situations. 

The prawn's life cycle varies and they go through three different life cycles. Estuarine, Marine, and Mixed are the three categories. The Estuarine life cycle is completed in seawater. The greasy back prawn is one subspecies that goes through this life cycle. Royal red prawns are part of the marine life cycle and dwell in ocean environments. Because it is the life cycle that baby prawns follow, the mixed life cycle is distinct. Female prawns shed their fertilised eggs at the ocean's bottom during this life cycle. Until the babies are ready to be born, the eggs remain on the ocean floor. This cycle continues until a child reaches adulthood. Over the course of two to three weeks, the mixed life cycle occurs.

Prawn Eggs - Fertilized eggs hatch in less than 24 hours, and larvae spend time floating in the sea, maturing through several stages as they move shoreward to shallow, hypersaline (very salty) waters. They are known as 'postlarvae' when they reach these shallow waters and are ready to settle on the bottom, where they will develop into young prawns. They can stay in the nursery zones for up to six months until reaching a size (near maturity) that requires them to return to oceanic waters to mate and spawn, finishing their life cycle. 

Migration of Prawns- The prawns enter the trawling grounds (often sandy or muddy-bottomed areas) during this migration, where they can be harvested commercially for the first time. These places are often located offshore, in waters ranging from 10 to 30 metres deep. This migration occurs every year in the summer and autumn and is referred to as "recruitment" in the industry.


Reproduction in Prawns

A mature female prawn is significantly larger than a mature male prawn. It is simple to determine if a prawn is male or female. Between the legs of a male shrimp is an organ called a pestama. A thelycum is a part of a female shrimp that allows her to mate with male prawns. Their ovaries turn an orange-brown tint as they age. The male's shell must be hard and the female's shell must be soft in order for a pair of prawns to spawn. The eggs of a prawn are fertilised while they are still inside a female body. It's thought that spawning occurs shortly after the eggs have been fertilised. Female prawns can become pregnant many times during the mating season. Females of various sizes and species are capable of carrying varying numbers of eggs. During the winter, king prawns living elsewhere will not spawn. The ovaries of adult female prawns are visible. They can be found in her head and tail. Ovaries are pale yellow or olive in colour before they mature.


Possible Threats to Prawns

Predators prey on both young and adult prawns. They are most vulnerable when they are in the larval stage of their development, though they might be victims at any time. They are frequently destroyed by bottom-dwelling or the demersal species like squid and cuttlefish during this time. They are especially vulnerable during the larval stage when predators cause a high incidence of death.


Interesting Facts About Prawn

  • Role of Prawns in Ecosystem- Many shrimp and prawns species are active scavengers, while others function as cleaners, helping to rid host fishes of external parasites, fungi, germs, and dead tissue present on the skin.

  • Use of Prawns by Humans- Prawns are considered one of the healthiest foods in the world by a number of health professionals due to their numerous nutritional benefits. Prawns are an excellent source of high-quality protein, as well as some of the most essential vitamins and minerals for a balanced diet. They have a surprisingly low-calorie count and are high in heart-healthy cholesterol and hence frying prawns help consume the nutritional element of the prawn fish. Selenium, one of the most efficient antioxidants for supporting healthy cells, is abundant in prawns. They also have a lot of zinc, especially the dry prawns which is necessary for a healthy immune system to develop. Prawns contain phosphorus, copper, and magnesium, which help to create strong bones. Due to so many benefits, there is a huge market in the culinary industry for frying prawns or even consume them in curries or recipes like spaghetti and pasta. The large prawns especially are often consumed by frying them in a barbeque structure and these frying prawns are relevantly named crispy prawns. 

FAQs (Frequently Asked Questions)

1. How Can We Identify Prawns From Shrimp?

Answer. Prawns live in both fresh and saltwater, however, unlike shrimp, the majority of kinds live in freshwater. The majority of prawn species prefer warmer water. In the Northern Hemisphere, however, many species can be found in cooler waters. Prawns prefer calm seas where they can perch on plants or rocks and lay their eggs comfortably.

2. Do Prawns Have The Ability to Swim?

Answer. Prawns, unlike fish, lack fins that allow them to swim, yet they can still move around in the water. A shrimp "swims" by rapidly drawing its abdomen toward its carapace (body). They are propelled through the water by this motion. Swimming crustaceans with long, narrow muscular abdomens and long antennae are known as prawns.

3. Where Can One Catch Prawns?

Answer. Prawns are caught in a variety of places. The majority of tropical prawn species may be found in tropical and subtropical waters around Australia. They can be found from Shark Bay in Western Australia to midway down the New South Wales coast, as well as along the Northern Territory and Queensland coastlines including seas in the Torres Strait between Australia and Papua New Guinea.