Interesting facts about the saw shark. Sawfish: all the details of underwater life The sawfish is the closest relative of whom

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 to 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 numerous evidence of how these bottom fish quickly burst into schools of sardines or mullet and how real fencers hit their prey with a saw, which they calmly ate after it sank to the bottom. The saw fish 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 its commercial value, it is very small, since the meat of the common sawfly is quite coarse, 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 it is still far from being a giant freshwater stingray. 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? It's very simple. In sharks, 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 endless latitudes of the ocean accommodate a very large number of different inhabitants. They differ from each other in interesting shapes, fancy names, colors and natural external features. Let's highlight several inhabitants depths of the sea, which have interesting properties and external features - sawfish. The full name of the fish is common sawfly(from Latin Pristidae).

This difficult inhabitant of the mysterious depths of the ocean differs from her “neighbors” by a bone growth on her head, which is very reminiscent of a saw. In this case, the saw is almost half the length of the fish itself. It belongs to the stingray family, but does not have a spine in its structure, which is a distinctive feature of many representatives of the subspecies. There are several varieties of sawfish - the saw shark and the sawfish ray.

Quite often, sawfish are confused with the so-called saw sharks. The thing is that they are very similar in appearance and both have skin consisting of placoid scales;
The sawfish was listed in the Red Book;
These fish mainly live on the coasts of the Atlantic and Pacific Oceans, as well as in the Mediterranean Sea;
Representatives of this species give birth to fully formed children in eggs; they have never laid eggs;
It is completely impossible to find it in the open ocean, but it feels great in coastal areas;
Sometimes they end up in big rivers, which flow into the ocean and remain to live in them;
They feed on very small animals that live at the bottom of sand or silt;
There has long been a legend that a sawfish could easily saw through an entire wooden ship;
The meat of this fish is usually not given special attention due to its toughness;
The length of the fish is from 4.5 – 5 meters. But sometimes there are individuals with a body length of about 7 meters. The weight category is also quite large, about 300 kg;
Fish are born with a long and soft saw, covered with small teeth and its length in adults is approximately 100-120 cm;
The saw is her main weapon, which is how she sometimes gets food for herself;
It does not pose any danger to humans;
In nature, there are not only sawfish like sharks, but also like stingrays;
Many cultures used the basic image of the sawfish as a tribal symbol (Aztecs);
The sawfish ray is the main symbol of the West African central bank;
We can meet sawfish in the cartoon about the “blue puppy”;
The pregnancy of a female fish lasts for 5 months and the offspring reaches 14-15 individuals;
The sawfish is very sensitive to the electric field that is formed as a result of the movement of potential victims and in this case it is easier for it to hunt, so this species can be classified as a dangerous and dexterous predator;
Scientists have proven that some species of sawfish can reproduce without the direct participation of males in this process, and their young will have an exact copy of the mother - parthenogenesis (this is explained by the fact that this species is disappearing, and nature is helping to restore the natural balance). Recently, this process of reproduction has spread and occurs quite often.

Differences between saw shark and saw ray

Let's look at some important differences between these species, as they often confuse even the most experienced researchers.

The saw shark is not significant in size compared to saw-blade rays (6 m or more); their length, including the tool, is only about 1.5 m;
Another significant difference involves the presence of gill slits on both sides of the body in sharks, and on the lower part of the body in rays;
These species are also distinguished by the presence and outline of fins - in sharks they look separated from the body, and in stingrays they are distinguished by a smooth transition to the body;
Another significant difference relates directly to the “tool” of these two species of fish. In sharks, the “saw” is slightly narrowed towards the end and the teeth on it are of different sizes, especially in the middle of the row. In stingrays, on the contrary, the “saw” is very neat, of the same size and the teeth have the same structure and shape;
An interesting fact is that sawn sharks recover broken teeth over time, while stingrays do not grow back even after minor damage;
Sharks grow long mustaches on their “tools,” which stingrays do not have;
Sharks move with the help of the well-known fin, so it is very easy to distinguish it from a stingray, which moves with wavy movements;
Many people are interested in the meat of sawnose sharks; in some countries it is a local delicacy, which cannot be said about the meat of sawfish rays.

The main use of the fish's "tool"

Fish of this species use their weapons at all stages of hunting and capturing their potential victims. They strike animals with their electric weapons and impale their prey on the teeth that run the entire length of the saw. The speed of their movements is simply elusive. They deftly handle the tool and immediately inflict several side blows on the victims.

The saw in their case acts as the main electric search engine, which easily finds various species of animals living in the depths of the ocean. It is not difficult for them to detect and capture prey that was several layers of water higher than them.

Now these listed interesting facts about the life of fish various types, will help even the most inexperienced ichthyologists to easily find the distinctive features between them. Their most important difference is already visible to the naked eye - it is hidden in their different names. There is an opinion that the sawfish, thanks to its tool, is very clumsy, but having paid attention to the way they hunt, catch prey and dexterity, thanks to the same tool, this myth simply dissolves.

Some sea creatures 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 their heads. 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 a single genus, containing seven species.

Sawfish can be found in the subtropics and tropics of all oceans. Habitat for different types there may be not only sea waters, but also fresh water bodies (for example, the Australian sawfish constantly lives in the river). Among them there are euryhaline species that thrive in both salt 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, and their liver, rich in fat, is used to maintain buoyancy.

The pectoral fins are wide, wing-like. They are fused with the head and play an important role in the stingray's swimming (by making strokes). 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 attachment of its teeth in the cartilaginous tissue of the 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.

Its natural enemies in the sea are sharks and aquatic mammals, and in rivers - 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, just like they do. 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 feed on small fish and various invertebrates that live in the ground.

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 predominant 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 sawfish ray is a migratory species and makes massive seasonal movements: in the summer from southern to northern waters, 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 formations that are 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 in traditional medicine. Of particular value is the unique rostrum, the cost of which reaches or exceeds $1,000.

The reason for the vulnerability of sawfish is their formidable weapon - a jagged "saw", which often becomes entangled in the accumulation of 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 the deteriorating environmental situation in the waters of the world's oceans, has been assigned the status of "Endangered" by the International Union for Conservation of Nature.

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.

The saw shark (sawnose shark) is one of the shark species best known for its sawfish. In the waters of Japan, Australia and South Africa There are about 8 different species of sawnose sharks. Saw sharks live in temperate coastal waters, typically at depths of 40 meters (130 ft). These interesting creatures are often killed for their tasty meat. Sawnose shark numbers have declined over the past few decades due to commercial fishing, but they are still not listed as a threatened species.

Interesting facts about the saw shark
1. The saw shark has a unique snout.
This shark has a long, flat blade called a snout, which has approximately 20 teeth on both sides. This snout can be used to catch fish and also has electroreceptors to detect passing prey.

2. These teeth are not real teeth.
In fact, the “teeth” on a fish’s snout are not really teeth. These are modified setae or rostral teeth. This shark's real teeth are located inside its mouth, which is on the underside of the fish.

3. The saw shark is closely related to sharks and rays.
Sawnose sharks are elasmobranchs - these are fish whose skeleton consists of cartilage. They are part of a group that includes sharks and rays. There are more than 1,000 species of elasmobranchs. The sawnose shark is in the family Pristiophoridae, a word that comes from the Greek word for saw. NOAA's website refers to them as "modified stingrays with a shark-like body."

4. The saw shark can grow over 5 meters in length.
The saw shark can reach 5 meters in length and weigh up to 18.7 pounds. Females are slightly larger than males.

5. The saw shark is found in shallow waters.
Watch your feet! Saw sharks live in shallow waters, often with mud-like or sandy bottoms. They can also swim up rivers.

6. The saw shark eats fish and crustaceans.
Sawnose sharks eat fish and crustaceans that they locate using the sensory capabilities of their sawfish. They kill fish and crustaceans by cutting them with their saw. The sawfish can also be used to locate and hunt prey on the ocean floor.

7. Saw sharks are ovoviviparous.
Reproduction occurs through internal fertilization. Their young are in the eggs, but the eggs develop inside the mother's body. The young feed on the yolk sac. After several months of pregnancy, the eggs hatch inside the female body. The female can give birth to from 3 to 22 sharks (usually 10 sharks). Depending on the species, pregnancy can last from several months to a year. Baby sharks are born with the saw blade unfolded, but it is padded and elastic so as not to injure the mother at birth. They are born fully developed and look like a miniature version of adult sharks.

8. The saw shark population has decreased.
There appears to be no reliable data on saw shark populations, but NOAA estimates that shallow-water saw shark populations have declined by 95 percent or more, and large saw shark species have declined even more. Threats to sawnose sharks include: fishing, fishing tackle and habitat loss due to development. The latter is especially true for young sharks that seek refuge in vegetation in shallow waters.

9. The body of the saw shark is covered with placoid scales (called dermal denticles) pointed towards the top. Saw sharks have yellowish-brown skin covered with dark spots. The coloration of the skin provides camouflage (saw sharks blend easily with the sandy bottom).

Photo. Whiskers on the snout of a saw shark

10. The saw shark has a pair of whiskers in the middle of its snout. They are used as a sensory organ that makes it easier to detect prey.

11. The shark has two dorsal fins, but no anal fin. They also have 5 or 6 pairs of gills (depending on the species) located on the side, behind the head.

12. Even though sharks and sawfish (sawfish rays) are similar in appearance, they differ in several aspects. Sawfish are larger, they do not have whiskers and their gills are located on the underside of the body (like stingrays).

13. Like other shark species, the saw shark uses an organ called the ampullae of Lorenzini, which contains electroreceptors to detect prey.

14. The shark uses its serrated snout to kill its prey. Rapid movement of the snout from side to side cuts the prey into small pieces, which can then be easily swallowed.

15. The saw shark is a carnivore (meat eater). Its diet consists of various types of fish, crustaceans and squid.

16. The saw shark can live as a solitary creature or be part of a group called a school.

17. Mating season for sawnose sharks occurs seasonally in coastal areas. Females mate once every two years.

18. The saw shark cares for its young until they are sexually mature (at 2 years of age) and can fend for themselves.

19. Saw shark in wildlife can live more than 15 years.

Photo. Saw shark T-shirt

Saw shark attacks on people
Sawnose sharks are considered harmless to humans, but if you try to catch them or free them from a fishing net, they can cause serious injuries. Although their teeth do not contain poison, their wounds can ache and take a long time to heal. Sawnose sharks have never attacked people.

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.

Ichthyologists are of the opinion that the length of the sawfish reaches almost five meters, although there is unconfirmed documented evidence that fishermen caught specimens about six meters in length.

This species of fish is listed in the International Red Book and lives in the coastal parts 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.

It also happens that it enters large rivers that flow into the ocean, and some of the sawfish species, for example, the Australian sawfish, have become so accustomed to fresh water that they live permanently in the rivers of the Green Continent.

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 numerous evidence of how these bottom-dwelling fish quickly burst into schools of sardines or mullet and how 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 its commercial value, it is very small, since the meat of the common sawfly is quite coarse, although quite edible.

Well, the final photo :)