Some Marine life got their names due to their external resemblance to some objects, things or tools. For example, a fish is a saw: the photo shows that the head has a long, wide outgrowth, very similar to a double-sided saw (hacksaw), which is well known to skilled people.
Two groups of cartilaginous fish – sharks and rays – have this unusual “detail” on the front of the head. But the name “saw” was assigned specifically to saw-tailed rays, and this article contains information only about these fish. About sawnose sharks and detailed description how to distinguish them from saw-tailed rays.
Order Sawtooths
Among Cartilaginous fish there are two superorders, one of which is . It distinguishes groups - squads. The Sawtooth-like order is very original due to its elongated snout, which looks like an elongated rectangle with large sharp teeth along the perimeter. In this small group there is only one family called Sawfishes (Pristidae), known as sawfishes. There is only singular gender, including seven species.
Sawfish can be found in the subtropics and tropics of all oceans. Habitats for different species can be not only sea waters, but also fresh water bodies(for example, the Australian sawfly lives permanently in the river). Among them there are euryhaline species that feel great in both salty and fresh water. Thanks to this feature, these fish enter rivers from the sea, rising quite far upstream.
Appearance Features
The sawfish, the photo of which you see below, has a flattened body, but its shape is very similar to:
- the body is equally elongated;
- the tail is practically not separated from the body and is its continuation;
- there are two large high dorsal fins;
- in some species the caudal fin has two lobes;
- The skin is covered with placoid scales.
It is especially easy to confuse a sawnose ray with a sawnose shark. To prevent such confusion from happening, you need to pay attention to the abdominal part of his body. Here there are gill slits, which are located in two rows in front of each pectoral fin on the right and left. The slit-shaped mouth and two nostrils in front of it (often mistaken for eyes) are very similar to the "face". But the real eyes of the sawfish are located on the upper (dorsal) part of the body. They are small, and behind them there are sprays, thanks to which water is pumped through the gills, which allows the sawfish to remain at the bottom almost without moving.
These stingrays do not have a swim bladder, but serve to maintain buoyancy. rich in fat liver.
The pectoral fins are wide, wing-like. They have grown together and are playing important role when a stingray swims (making flaps). There is no anal fin. The dorsal side of the body is dark in color, and the ventral side is light. Sawfish rays are large fish and can reach more than 7 meters in length (European sawfish), and the smallest of them (Queensland sawfish) is only 1.4 meters. Now you have a good idea of what a sawfish looks like. Sawfish live up to 80 years.
“Saw” and its functions
The saw-tailed ray uses its unusual tool for two purposes:
- detect potential prey;
- and catch her (stun and immobilize).
A special feature of the structure of the “saw” (scientifically it is called “rostrum”) is the deep and strong fastening of its teeth in cartilage tissue rostrum. If one of the teeth breaks or is damaged, it will never grow again. Saw-nosed rays of different species have from 14 to 34 pairs of teeth. They all have the same size.
All sawfish rays are divided into two conditional groups: one has large saw teeth, and the second group has small teeth. The sawfly also has teeth in its mouth, but they are small in size.
Rostral teeth and protection from enemies
The rostral (located along the edges of the rostrum) teeth of the sawfish are not teeth, but modified placoid scales, found only in cartilaginous fish (the structure of such scales is actually a little similar to teeth).
The long rostrum, armed with sharp, strong “teeth,” is a powerful tool not only for obtaining food, but also for protection from enemies. Swinging this cutting and piercing tool from side to side, the saw-nosed stingray successfully defends itself.
His natural enemies there are sharks in the sea and aquatic mammals, in the rivers there are crocodiles. After all, some species (for example, the European sawfly) enter rivers and can remain there for a long time. Observations of stingrays kept in aquariums also indicate the use of the “saw” for protection.
Electroreception and prey search
We continue to get acquainted with the formidable “weapon” of the saw-tailed ray – its elongated rostrum-saw. On the surface of the “saw” there are numerous electroreceptors that help find food objects in muddy water, the same way they do it. Ampullae of Lorenzini (organs that capture electrical fields from animals) in large quantities are located on the upper surface of the rostrum. This makes it possible for the sawfish to receive information about living objects that float in higher layers of water above it and often become its prey.
Sawfish rays do not feed big fish and various invertebrates living in the soil.
With their flat saw, saw-tailed rays dig the ground to extract burrowing invertebrates, most often these are mollusks and crustaceans. Sometimes they use the saw as a saber. Bursting into a cluster of small fish (mullet or sardines), the stingray swings its weapon and hits the prey, which falls to the bottom. Having descended after the struck victims, the sawfly swallows them.
Lifestyle and biology
The primary habitat of sawfish is shallow waters. The depth is sometimes so shallow that both high dorsal fins of the stingray lying at the bottom stick out above the surface of the water. Off the American coast, the saw-tailed ray is a migratory species and makes massive seasonal movements: in the summer from southern waters to the north, and in the fall they return to the south again.
All sawflies reproduce by ovoviviparity. Embryos develop in the mother's body, being in the egg and feeding only on the yolk, in contrast to, and, whose embryos receive part of their nutrition from the mother with the help of special education, vaguely similar to the placenta of mammals. On average, females of different species give birth to from 6 to 20 cubs.
The babies, while in the mother's body, already have a long snout, but it is soft, and its teeth are located under the skin. In newborns, the teeth of the “saw” are very small and reach their final length after birth.
Sawfish and man
There has been a commercial sawfish fishery for a long time. The rough meat of these stingrays is edible. But the fins, which are used to make soup, are of particular value. Liver fat is in demand traditional medicine. Of particular value is the unique rostrum, the cost of which reaches or exceeds $1,000.
The reason for the vulnerability of sawfishes is their formidable weapon– a jagged “saw” that often becomes entangled in debris floating in the water or in fishing nets. Poaching causes great damage to the numbers of all species of this group of stingrays. One of them (the Asian sawfish) due to overfishing and worsening environmental situation in the waters of the world's oceans International Union Nature Conservation has been assigned the status of "Endangered".
And in 2007, a ban was announced on the trade in body parts of all saw-tailed rays: these are fins, “saws” and their teeth, skin, meat and organs.
Sawfish ray or sawfish January 26th, 2017
This inhabitant of the World Ocean stands out among others in that it has a jagged bone growth on its head, which really resembles a saw and makes up approximately a quarter of the total body length.
The exact biological name of this fish is the common sawfish, and it belongs to the stingray family. On the back of a sawfish (lat. Pristidae) there are two fins, and one on the tail, and unlike many other stingrays, it does not have a spine.
Just like sharks, the skin of sawfish is covered with placoid scales. Due to their great external similarity, sawnose rays are sometimes confused with sawnose sharks, but they are a completely different family of fish.
They can be distinguished by the way their gills are located: sawfish, like all rays, have gill slits at the bottom of the head, and sawnose sharks have gill slits on its sides. Besides, the fish drank It is significantly larger in size than sawnose sharks.
This species of fish is listed in the International Red Book and lives in the coastal part of the Atlantic, Indian and Pacific Oceans, as well as in the Mediterranean Sea. Sawfish, which live off the coast of the American continent, migrate from south to north in summer, and from north to south in autumn.
The common sawfly does not lay eggs, but reproduces by ovoviviparity. One female Sawfish can give birth to fifteen to twenty babies at a time. Moreover, while they are still in the womb, their “saw” is completely covered with skin.
It is almost impossible to find sawfish in the open ocean. For its habitat, it has chosen coastal areas, and sometimes it enters the shallows, and then you can see the dorsal fins sticking out of the water.
It also happens that she comes into large rivers flowing into the ocean, and some of the sawfish species, for example, the Australian sawfish, have become so comfortable in fresh water that they live permanently in the rivers of the Green Continent.
The diet of sawfish consists mainly of a variety of small animals that live in the sand and silt covering the bottom. It is for this, and not for any carpentry work, that a sawmill needs a saw. With its help, this type of stingray loosens the bottom soil and digs out those unfortunates from it, who then go into food.
However, there is also evidence that the saw blade can be used by the sawmill not only as a shovel, but also as a kind of saber. There is ample evidence of how these bottom fish They quickly burst into schools of sardines or mullet and, like real fencers, hit their prey with a saw, which they calmly ate after it sank to the bottom. The sawfish became so famous due to its unusual appearance. Previously, there was even a legend that she was capable of sawing a wooden ship, and that is why even experienced “sea wolves” were afraid of meeting her. However, in fact, this fish is not at all dangerous for humans, and, like most other species of stingrays, when it encounters it, it often tries to quickly hide.
As for her commercial value, then it is very small, since the meat of the common sawfly is quite rough, although quite edible.
The largetooth sawfish (Pristis perotteti) is now firmly established in the inland waters of its habitat. For example, the population found in Lake Nicaragua appears to be entirely freshwater and may represent a distinct species distinct from sawfish rays found in waters along the coasts of Central America.
Like many sharks, sawfish rays produce litters of live young. The body of a pregnant female fish, caught off the coast of Sri Lanka, contained 23 fry. To make the process of pregnancy and childbirth less painful, the fry's teeth are covered with a protective shell, and the stigmas remain soft and flexible until the offspring are born.
The sawfish has a very impressive size, but up to a gigantic freshwater stingray she still has a long way to go. The average length of her body is 4.5-4.8 meters. There are also larger individuals, 6-7 meters. It also weighs a lot - this is how a stingray 4.2 meters long was caught, the weight of which reached 315 kilograms. The heavyweight record belongs to a stingray weighing 2.4 tons. It's a pity that its length is not indicated anywhere.
These rays are born with a long but soft snout with small teeth hidden under a leathery shell so as not to damage the mother. In adult individuals, the length of the “saw” can reach 110-120 centimeters.
Unlike other species of stingrays, the sawfish does not have a spine on its caudal fin. Some people confuse these stingrays with sawnose sharks, which they closely resemble. How can you tell them apart? Everything is very simple. In sharks, the gills are located at the edges of the head, while in stingrays they are located at the bottom. In addition, the latter have a flattened body, the edges of the pectoral fins are fused with the head at the level of the mouth. All these features, as well as the absence of antennae on the snout, distinguish saw-nosed rays from saw-nosed sharks (Pristiophoridae).
Now we come to the answer to the question - why does a fish need a saw? It turns out that with its help, the stingray digs out small fish hidden from it from the silt and sand. In addition to the fact that the saw serves as a kind of “shovel” for him, it is also a formidable weapon. Having burst into a school of fish, the stingray furiously begins to swing the “saw” from side to side. After this, it calmly sinks to the bottom and swallows the wounded or “sawed” fish. This fish is completely safe for humans.
The scientific name of this creature is the common sawfly. The sawfish belongs to the family of cartilaginous fish (like the shark) and to the superorder of stingrays. This creature received its name and wide popularity due to its appearance. The sawfish has an elongated body, strikingly similar to a shark, but perhaps the most striking external feature that distinguishes it from other fish and rays is the so-called “saw” - a long and flat outgrowth of the snout, on the sides of which there are sharp teeth of the same size. It is curious that this “saw” is almost a quarter of the body length of the entire fish! The sawfish's skin has various shades of gray-olive color, and its belly is almost white.
The sawfish's shark-like body has 2 fins on each side and 2 triangular-shaped dorsal fins. In some species of saw-tailed rays, the tail part smoothly passes into the body, merging with it, but there are also species in which the tail and body are divided into two sections by the caudal fin. It is curious that the similarity of these fish with sharks does not end only with the shape of their body: sawfish, like sharks, have skin covered with placoid scales. Currently, only 7 species of saw-tailed rays are known: green, Atlantic, European, smalltooth, Australian, Asian and combed.
Where do sawfish live?
The sawfish feels comfortable in both fresh and salt waters, and lives in all oceans except the Arctic Ocean. Favorite place saw-fingered rays – coastal waters. This creature is difficult to find in open oceans. Sawfish love to bask in shallow water. It is curious that 5 of the 7 currently known species of sawfish live off the coast of Australia. Australian species In general, sawfish have long been accustomed to fresh water bodies, without swimming into the ocean. The only place where sawfly rays cannot live is in polluted various garbage and water waste.
Sawfish and sawnose shark are not the same thing!
Saw-nose rays are often confused with saw-nose sharks. These are not the same fish! Of course, sharks are the closest relatives of rays, since they belong to the same family of cartilaginous fish, but these are two different types underwater animals. The sawnose shark's snout is elongated and flattened, similar to a sword, and studded with large teeth. This creature lives in warm waters Indian and Pacific oceans. Sawfish are bottom-dwelling and slow-moving fish that feed on small fish and small bottom-dwelling animals.
Sawfish are considered larger fish than sawfish. A case is described in which a sawfish weighing 2400 kg and 6 m long was caught! For comparison: sawwhiskers rarely grow to 1.5 m in length. Sawfish, like their “comrades” the sawfish, feed on small animals living in the ground. They dig them out of the mud with their "saw", using it both as a shovel and as a rake. Often the sawfish wields its nose like a saber or sword, bursting into a school of small mullet or sardines, and then swallows the “defeated” enemies.
Sawfish is an ovoviviparous fish
Sawfish belong to ovoviviparous fish: their young are born as fully formed fish, but located in the shell of a leathery egg. Zoologists who observed saw-throated rays found that their females can give birth to up to 20 young at a time! The “saw” of these fry is formed in the womb, but their stigma is still very soft, and the teeth are completely hidden by the skin and harden only with time. By the way, in the same way
Belongs to the group of cartilaginous fish. This group includes sharks (typically represented by -), rays and skates. All cartilaginous fish have a skeleton made of cartilage tissue, as opposed to a skeleton made of bone like other fish such as snook, red drum, or tarpon. The sawfish is a chordate and belongs to the family Pristidae. The sawfish has a characteristic elongated, flat snout, similar to a sawtooth, and a body appearance and swimming style are more reminiscent of a shark. The saw-like appendage makes up approximately 20% of the total body length. Once a fish loses some of the teeth on its snout, they no longer grow back.
General description and characteristics of sawfish
Sawfish have been little studied around the world and no one knows for sure the exact number of fish species in this group. Scientists estimate that seven species of sawflies are currently known to exist around the world: green, Atlantic, European, smalltooth, Australian, Asian and combed. Two species that exist in the western Atlantic Ocean are the sawfish and the smalltooth sawfish. Both species look very similar, but can be differentiated by counting the saw teeth on either side of the snout. Sawfish typically have 23 to 34 teeth on each side, while smalltooth sawfish only have 17 to 22 teeth. Both species are found in Florida, but only 3 smalltooth sawflies have ever been recorded in the state. The smalltooth sawfly's typical range is further south and west of the United States. The sawfish is by far the most commonly found fish on both coasts of Florida. Hundreds of specimens of this fish have been recorded throughout Florida, but last decade or so most of them are in the southwest of the state.
Where does the sawfish live?
Sawfish are most often found in the western Atlantic from Brazil to Florida, including Gulf of Mexico. Several species of sawfish are found off the coast of Australia. Sawfish prefer to live in the coastal strip, but cannot exist in waters polluted by garbage and waste. Sometimes they swim so close to the surface of the water that a large dorsal. Sawfish are found in both sea and fresh water. Residents of the Florida peninsula can see these fish almost all year round V warm months. Sawfish were once common throughout the state's waters, especially in the late 19th and early 20th centuries.
In the late 1800s, a fisherman reported catching approximately 300 sawfish in one fishing season with his net. Other fishermen have reported seeing sawfish "big and small" along the peninsula's western coast. Although there are no published studies, sawfish population declines have been documented. This is believed to be due to commercial fishing activities (nets, trawls, seines) that have directly or indirectly contributed to the problem.
Sawfish: meaning for humans
Because of unusual shape The body of a sawfish easily becomes entangled in nets, and they cause significant damage to it. Sawfish have minimal commercial value. Its meat is quite rough and is not used for food. Most of the specimens caught either suffocated or were killed. Sport fishing has a lesser impact Negative influence on the population of these fish in Florida. Sawfish have historically been popular in the curio trade.
Harvesting-related mortality of the fish, combined with its limited reproductive capacity, caused population declines in Florida during the second half of the 20th century. Because of this, sawfish have been banned from catching in Florida since 1992. Since April 1, 2003 national service marine fisheries The sawfish has been declared an endangered species in the United States. This declaration gives this species federal protection under the Endangered Species Act since May 1, 2003. One day, while sport fishing, an 8-foot-long specimen was caught and released.
What does sawfish eat and how to catch it
The sawfish's main diet consists of crabs, shrimp and other bottom-dwelling invertebrates, as well as small fish such as mullet and members of the herring family. Sawfish obtain food by digging through mud with their noses in search of prey. Sometimes she breaks into a school of smaller fish and, waving her nose, rolls them onto the teeth before eating them.
Sawfish, like other representatives of this group of fish, can be caught on a hook with bait from fresh or frozen fish or shrimp. The sawfish can also use its nose for protection. Therefore, while swimming, she swings it vigorously from side to side. Caution must be exercised when approaching sawfish of any size. Although the sawfish will help protect itself from a threat, the only case of an unprovoked attack on a person was recorded on south coast Atlantic Ocean with a small fish up to a meter long - it injured a man's leg. Other attacks on people, most of which were almost always provoked, have been reported in Panama City Bay. There is a fact of unconfirmed attacks off the coast of India.
Reproduction of sawfish
Very little is known about the size, age, maturity, and reproduction of sawfish throughout Florida. This fish can grow up to 6 meters in length, and the weight of some specimens reaches 300 kilograms. Female and male smalltooth sawflies in Lake Nicaragua reach sexual maturity at a length of approximately 3 meters. Sawfish are ovoviviparous and reproduce by internal fertilization, just like sharks and rays.
Embryos in the uterus grow without a placental connection with the mother and are fed by the yolk stored in tissue cells connected to the embryo. The gestation period of the sawfish is little known, but for the smalltooth sawfish it lasts about 5 months. Young fish are born in late spring and throughout the summer in South Florida. The female brings 15-20 cubs and they are born in a leathery egg, inside of which there is a fully formed fish.
There was such a case. Up to 20 young individuals died after being washed ashore. The length of each of them ranged from half a meter to eighty centimeters. Before birth, the teeth of the saw are soft and not fully developed, so as not to injure the mother. After birth they quickly reach a proportional size.
Do sawfish have teeth or spines on their nose?
In fact, saw teeth are not teeth at all, but rather modified spikes. They are covered with scales. The sawfish's reproductive cycle is unknown, but the smalltooth sawfish produces offspring every second year of its life. Both species grow very slowly and reach maturity by 10 years, and can live up to 30 years or more. Sawfish in Florida are most commonly found in estuaries and bays. They used to be numerous, but now they are rare. Sawfish are found in a wide range of habitats, including seagrass, mud bottoms, sandy bottoms, artificial reefs, mangroves coastlines, bridges and piers. They can also be found several kilometers from rivers in low salinity conditions. Large specimens can be found in estuaries and lagoons, artificial reefs or wrecks.
Tropical waters are teeming amazing creatures. One of them is the sawfish. Reaching quite impressive size with its terrifying appearance, it has long become the object of legends and various fictions. For example, that with its unusual growth on its head it can easily saw through ships. A completely baseless fabrication. Let's take a closer look.
What does a sawfish look like?
Focusing solely on appearance, many believe that this is a kind of shark. But in fact, it belongs to the family Saw-nosed rays (class Cartilaginous fish), in which modern stage only seven representatives remained. These are Asian, small-toothed, Australian (or Queensland), combed, European (differs in the largest size - up to 7 m), Atlantic and green sawflies. The sawfish has a shark-like elongated body. It is covered with placoid scales, has two fins on the back and one tail. The body color is olive-gray, but can vary depending on the species and habitat; the belly is light, almost white. A distinctive and outstanding feature is the so-called “saw”, or rather the outgrowth of the snout. It is long and flat in shape, with identical teeth on the sides. They give it the appearance of a saw. And if we talk about length, it is approximately ¼ of the entire body size of the fish. Considering that individual individuals can reach 7.5 meters, the sawtooth growth is up to 2 m, and this is quite an impressive and terrifying weapon.
Habitat of the sawfish
This is an inhabitant of the coastal tropical waters of three oceans: Atlantic, Pacific and Indian. In addition, it is sometimes found in the Mediterranean Sea and off the coast of America. This is explained seasonal migrations. Sometimes it swims into river mouths. The sawfish (photo) also feels quite comfortable in them, but it does not tolerate anthropogenic water pollution at all. Five of the seven species live in Australian waters, and one (Queensland) has completely adapted to life in a fresh environment and no longer swims into the ocean. The sawfish is an inhabitant of shallow waters, and very often you can clear water make out its body or determine its location by its fin above the water, which is why it is often confused with a shark.
The sawfish is a predator, and quite a dangerous one at that. Not having sharp teeth like a shark, it can seriously injure with its snout. There are two ways to get food. The first (predominant) is the collection of small invertebrate animals from the bottom and from the sand. The “saw” allows the fish to tear up the soil, like a shovel, thus obtaining food. The second method is more aggressive. Bursting into schools of fish (sardines, mullet), the stingray begins to actively swing its “saw” in different directions for some time. It then sinks to the bottom and collects mangled or cut up prey. For humans, the sawfish does not pose a danger, rather the opposite, but it is still not worth deliberately angering it.
Reproduction of saw-fingered rays
The sawfish is an ovoviviparous fish. This means that the egg develops in the mother's body, and at birth the baby seems to be enveloped in a dense shell. Nevertheless, he is already quite viable and independent. Saw-tailed rays can give birth to up to twenty young. The “saw” of young individuals is quite soft; strength and hardness are acquired only with time. When the cubs are in the womb, all the denticles are hidden by the skin and are revealed only when they are born.
Sawnose shark: what's the difference?
It, like the sawfish, belongs to the class of Cartilaginous fish. However, it is a representative of another family, namely saw sharks. Sawfish differs from it in the following ways: external signs(not to mention anatomical differences):
- Dimensions. The first species is much larger, there were specimens with a length exceeding six meters, while the saw shark reaches up to best case scenario 1.5 m.
- Location of gill slits. So, in a sawfish they are located at the bottom, and in a shark they are on the sides.
- Fin shape. In the first type they are streamlined, smoothly blending into the lines of the body, and in the second they are clearly defined;
- Differences are also observed in the structure of the “saw” itself. In the sawmill, it is more accurate and even in width throughout its entire length, the same applies to the notches on it. In a shark, the growth narrows, and it will be interesting to know that the denticles, when damaged, are capable of regeneration, but in stingrays they are not;
- According to the nature of movement. The first moves smoothly, wave-like; the shark makes sudden movements, mainly with the help of the tail fin.
It is worth adding that sawfish is not a commercial fish, although it is edible. When caught in a net, it is more likely to be taken as a trophy than as food. But the saw shark has tasty meat and is considered, for example, a delicacy in Japan.
Now this inhabitant of shallow ocean waters is listed in the International Red Book, and the reason for this is man. With anthropogenic pollution coastal waters the sawfly simply has nowhere to live.
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