The structure of the Cyclops. Cyclops crustaceans: structure, nutrition, coloring, reproduction, breeding, significance for humans, interesting facts, representatives, photos
Which is why they got their name. The antennae of Cyclops are short, and the antennae used for swimming are single-branched. They don't have a heart. About 250 species are known, distributed throughout the globe. They usually live at the bottom of freshwater reservoirs, and only a few live in the water column. Cyclops are predators and feed on protozoa, rotifers, and small crustaceans. They themselves serve as food for many fish and fry. They can serve as intermediate hosts for parasitic worms (guinea worm, broad tapeworm and others).
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Cyclops Cyclops Scientific classification Kingdom: Animals Type ... Wikipedia - (Greek, i.e. round-eyed, from kyklos circle, and ops eyes). IN Greek mythology : sons of Uranus and Gaia, giants who had only one round eye in the middle of their forehead; they forged thunder arrows for Jupiter; considered mythical builders. Dictionary… … Dictionary foreign words
Russian language In perch fish anal fin contains 1 3 spines. The dorsal fin consists of two parts: spiny and soft, which are connected in some species and separate in others. The jaws have bristle-like teeth, among which in some species sit... ...
Biological encyclopedia
Cyclops (Cyclopidae), family of copepods. Body length 1–5.5 mm. There is an unpaired frontal ocellus (hence the name). The antennules are short, the antennae are single-branched (used for swimming), the abdomen is longer than the cephalothorax, in females with two eggs... ... I Cyclops see Cyclops. II Cyclops (Cyclopidae) family of copepods (See Copepods). Body length 1 5.5 mm. There is an unpaired frontal ocellus (hence the name). The antennas are short, single-branched antennas (serve for... ...
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- (Ioseph Saunders); engraver with a chisel; worked in St. Petersburg since 1794. He was listed as His Majesty's engraver at the Hermitage, with a salary of 1200 rubles; Aug 18 In 1800, he was elected to academicianship for the engravings he presented: “Daughterly Love” and... ... Large biographical encyclopedia
A nematode from the Strongylidae family, Strongylus vulgaris, lives in the large intestines of horses. These are quite large yellow nematodes, the females of which reach a length of 20-21 mm (males 14-16 mm). The anterior part of the stoma carries... ... contains 1 3 spines. The dorsal fin consists of two parts: spiny and soft, which are connected in some species and separate in others. The jaws have bristle-like teeth, among which in some species sit... ...
Crustaceans are ancient aquatic animals with a complex body structure covered with a chitinous shell, with the exception of woodlice that live on land. They have up to 19 pairs of jointed legs that perform various functions: capturing and grinding food, movement, protection, mating, and bearing young. These animals feed on worms, mollusks, lower crustaceans, fish, plants, and crayfish also eat dead prey - the corpses of fish, frogs and other animals, acting as orderlies of reservoirs, especially since they prefer very clean fresh water.
Lower crustaceans - daphnia and cyclops, representatives of zooplankton - serve as food for fish, their fry, and toothless whales. Many crustaceans (crabs, shrimp, lobsters, lobsters) are commercial or specially bred animals.
2 species of crustaceans are included in the Red Book of the USSR.
general characteristics
From a medical point of view, some species of planktonic crustaceans are of interest as intermediate hosts of helminths (Cyclops and Diaptomus).
Until recently, the Crustacean class was divided into two subclasses - lower and higher crustaceans. The subclass of lower crayfish included phyllopods, jawed crayfish and shell crayfish. It is now recognized that such a unification is impossible, since these groups of crayfish are different in origin.
In this section, the Crustacean class will be considered according to the old classification.
The body of crustaceans is divided into the cephalothorax and abdomen. The cephalothorax consists of segments of the head and chest, merging into a common, usually undivided body section. The abdomen is often dissected.
All crustaceans have 5 pairs of head limbs. The first 2 pairs are represented by segmented antennae; These are the so-called antennules and antennae. They carry the organs of touch, smell and balance. The next 3 pairs - oral limbs - are used to capture and grind food. These include a pair of upper jaws, or mandibles, and 2 pairs of lower jaws - maxilla. Each chest segment carries a pair of legs. These include: jaws, which are involved in holding food, and locomotor limbs (walking legs). Abdomen higher crayfish also carries limbs - swimming legs. The lower ones don't have them.
Crustaceans are characterized by a bibranched limb structure. They distinguish between the base, external (dorsal) and internal (ventral) branches. This structure of the limbs and the presence of gill projections on them confirms the origin of crustaceans from polychaete annelids with bibranched parapodia.
Due to the evolution in aquatic environment crustaceans have developed organs of water respiration - gills. They often appear as outgrowths on the limbs. Oxygen is delivered by blood from the gills to the tissues. Lower crayfish have colorless blood called hemolymph. Higher crayfish have real blood containing pigments that bind oxygen. The blood pigment of crayfish - hemocyanin - contains copper atoms and gives the blood a blue color.
The excretory organs are one or two pairs of modified metanephridia. The first pair is localized in the anterior part of the cephalothorax; its duct opens at the base of the antennae (antennary glands). The duct of the second pair opens at the base of the maxillae (maxillary glands).
Crustaceans, with rare exceptions, are dioecious. They usually develop with metamorphosis. A nauplius larva emerges from the egg with an unsegmented body, 3 pairs of limbs and one unpaired eye.
Subclass Entomostraca (lower crayfish).
Lower cancers live as in fresh waters, and in the seas. They are important in the biosphere, being an essential part of the diet of many fish and cetaceans. The most important are copepods (Copepoda), which serve as intermediate hosts of human helminths (diphyllobothriids and guinea worms). They are found everywhere in ponds, lakes and other standing bodies of water, inhabiting the water column.
general characteristics
The body of the crustacean is divided into segments. The complex head bears one eye, two pairs of antennae, mouthparts, plus a pair of legs-jaws. One pair of antennas is much longer than the other. This pair of antennas is highly developed, their main function is movement. They also often serve to hold the female by the male during mating. Thorax of 5 segments, pectoral legs with swimming setae. Abdomen of 4 segments, at the end - a fork. At the base of the female's abdomen there are 1 or 2 egg sacs in which eggs develop. Nauplii larvae emerge from the eggs. The hatched nauplii look completely different from adult crustaceans. Development is accompanied by metamorphosis. Copepods feed on organic debris, tiny aquatic organisms: algae, ciliates, etc. They live in reservoirs all year round.
The most common genus is Diaptomus.
Diaptomus live in the open part of water bodies. The size of the crustacean is up to 5 mm. The body is covered with a rather hard shell, which makes it reluctant to be eaten by fish. The color depends on the nutrient base of the reservoir. Diaptomuses have 11 pairs of limbs. The antennules are single-branched, the antennae and legs of the thoracic segments are biramous. The antennules reach especially great lengths; they are longer than the body. Scattering them widely, diaptomuses float in the water, the thoracic limbs cause the jerky movements of the crustaceans. The oral limbs are in constant oscillatory motion and drive particles suspended in water towards the mouth opening. In Diaptomus, both sexes take part in reproduction. Diaptomus females, unlike Cyclops females, have only one egg sac.
Species of the genus Cyclops (cyclops)
inhabit mainly coastal zones of water bodies. Their antennae are shorter than those of diaptomus and participate, along with the thoracic legs, in irregular movements. The color of cyclops depends on the type and color of the food they eat (gray, green, yellow, red, brown). Their size reaches 1-5.5 mm. Both sexes take part in reproduction. The female carries fertilized eggs in egg sacs (Cyclops have two), attached at the base of the abdomen.
In terms of their biochemical composition, copepods are in the top ten high-protein foods. In aquarium farming, “Cyclops” is most often used to feed grown juveniles and small-sized fish species.
Daphnia, or water fleas
move spasmodically. The body of daphnia, 1-2 mm long, is enclosed in a bivalve transparent chitinous shell. The head is extended into a beak-like outgrowth directed towards the ventral side. On the head there is one complex compound eye and in front of it a simple ocellus. The first pair of antennae is small and rod-shaped. The antennae of the second pair are highly developed, bibranched (with their help, daphnia swims). On the thoracic region there are five pairs of leaf-shaped legs, on which there are numerous feathery bristles. Together they form a filtration apparatus that serves to filter small organic residues, unicellular algae and bacteria from the water that daphnia feed on. At the base of the thoracic legs there are gill lobes in which gas exchange occurs. On the dorsal side of the body there is a barrel-shaped heart. There are no blood vessels. Through the transparent shell, the slightly curved tube-shaped intestine with food, the heart, and below it the brood chamber in which daphnia larvae develop are clearly visible.
Subclass Malacostraca (higher crayfish).
The structure is much more complex than that of lower crayfish. Along with small planktonic forms, relatively large species are found.
Higher crayfish are inhabitants of marine and fresh water bodies. Only woodlice and some crayfish (palm crayfish) live on land from this class. Some species of higher crayfish serve as commercial fisheries. In the seas of the Far East, a gigantic Pacific crab is caught, whose walking legs are used for food. In Western Europe, lobster and lobster are caught. In addition, crayfish have sanitary significance, because... clear water bodies of animal corpses. Freshwater crayfish and crabs in Eastern countries are intermediate hosts for the pulmonary fluke.
A typical representative of higher crayfish is the river crayfish.
Order Copepoda
The head is equipped with 5 pairs of appendages. The anterior antennae are often very long, sometimes longer than the body, and are involved in swimming and soaring of crustaceans. In addition, they also perform the functions of sensory organs: sensitive bristles and cylindrical sensory appendages sit on them. The posterior antennae are short, usually biramous. The mandibles are powerful and have a two-branched palp. Their chewing, highly chitinized part has sharp teeth that help crush food. A careful examination of the teeth of the mandibles of some marine copepods revealed that these teeth are covered with flint crowns, which increase their strength (Fig. 203). The discovery of flint crowns is interesting in two respects. Firstly, it indicates the ability of copepods to assimilate and concentrate silicon; Almost all higher invertebrates - worms, mollusks, and other arthropods - lack this ability.
Secondly, one can hope to find in geological deposits flint crowns of ancient copepods, which are almost completely not preserved in fossil form.
The anterior jaws of copepods are very complex, as they are equipped with internal and external lobes and numerous feathery bristles. The hind jaws have only internal lobes and also numerous setae. The cephalic appendages are joined by a pair of single-branched jaws belonging to the anterior thoracic segment fused with the head.
The posterior antennae, palps of the mandibles and anterior jaws of filter-feeding copepods make frequent and continuous strokes, creating water cycles that bring suspended food particles. These particles are filtered out mainly by the bristles of the posterior jaws.
The thoracic region consists of 5 segments with clearly visible boundaries between them. All 5 pairs of thoracic legs in primitive copepods are constructed identically. Each leg consists of a 2-segmented main part and two usually 3-segmented branches armed with spines and setae. These legs make simultaneous strokes, acting like oars and pushing the crustacean's body away from the water. In many more specialized species, the male's fifth pair of legs is transformed into an apparatus adapted to hold the female during mating and attach spermatophores to her genital openings. Often the fifth pair of legs is reduced.
The abdominal region consists of 4 segments, but in females their number is often smaller, since some of them merge with each other. A paired or unpaired genital opening opens on the anterior abdominal segment, and in the female this segment is often larger than the rest. The abdomen ends in a telson, with which the furcal branches are articulated. Each of them is armed with several very long, sometimes feathery bristles. These setae are especially strongly developed in planktonic species, in which they are adapted for soaring in water, as they prevent the crustacean from immersing.
Copepods breathe over the entire surface of the body; there are no gills. Poor development or even absence of the circulatory system may also be associated with this. Only representatives of the suborder Calanoida have a heart, and even in them it is small, although it beats very quickly: for example, in the sea crustacean Labidocera it makes more than 150 beats per minute. In other copepods, the cavity fluid is driven by intestinal contractions.
During mating, the male holds the female with the fifth pair of thoracic legs and the first antennae and, using the same fifth pair of legs, glues the sausage-shaped spermatophore near her genital openings, i.e., to the underside of the first abdominal segment. In some species, one of the branches of the fifth pair of legs of the male is equipped at the end with forceps, capturing the spermatophore and transferring it to Right place(Fig. 204). From the spermatophore, the sperm enters the female's seminal receptacle. When the eggs are laid, they are fertilized.
Rice. 204. Mating Calanoida: 1 - attachment of the spermatophore to the genital segment of the female in Diaptomus; 2 - fifth pair of legs of Pareuchaeta glacialis; last segment of the left leg with “tweezers” holding the spermatophore
A nauplius larva emerges from the egg. The larva molts repeatedly and gradually approaches the characteristics of an adult crustacean. There are 12 larval stages of copepods. The first two stages - orthonauplius - are characterized by the presence of only both pairs of antennae and a pair of mandibles; in the next four stages - metanauplius - the remaining oral appendages are laid down and develop, but the body remains unsegmented. The last 6 stages are called copepodite and are distinguished by segmentation of the posterior end of the body and the gradual development of the thoracic legs. To complete metamorphosis, various copepods require different times, and the biology of larvae is not the same in all species.
The lifestyle, feeding method and habitat of copepods are so diverse that it is better to consider this order not as a whole, but each of its suborders separately.
Calanoida are exclusively planktonic animals. Their head and chest are much longer than the narrow abdomen, the anterior antennae are very long, exceeding the head and chest, and often the entire body of the crustacean; if there is an egg sac, then only one.
Harpacticoida, with a few exceptions, live on the bottom and crawl more than swim. Their body is worm-shaped due to the fact that the abdominal region is almost the same in width from the thoracic region. The anterior antennae are very short; females of most species form a single egg sac. Representatives of all three suborders inhabit both seas and fresh waters.
Suborder Calanida
The entire Calanoida organization is excellently adapted to life in the water column. The long antennae and feathery setae of the furcal branches allow the marine Calanus or freshwater Diaptomus to float motionless in the water, only sinking very slowly. This is facilitated by drops of fat located in the body cavity of the crustaceans, which reduce their specific gravity. During hovering, the crustacean’s body is positioned vertically or obliquely, with the front end of the body located higher than the rear. Having dropped a few centimeters down, the crustacean makes a sharp swing with all its thoracic legs and abdomen and returns to its previous level, after which everything is repeated all over again. Thus, the path of the crustacean in the water is drawn with a zigzag line (Fig. 205, 1). Some marine Calanoida, such as the near-surface bright blue species Pontellina mediterranea, make such sharp leaps that they jump out of the water and fly through the air like flying fish.
If the thoracic legs act from time to time, then the posterior antennae, palps of the mandibles and anterior jaws vibrate continuously with a very high frequency, making up to 600-1000 beats every minute. Their swings cause powerful water circulation on each side of the crustacean’s body (Fig. 205, 2). These currents pass through the filtration apparatus formed by the bristles of the jaws, and the filtered suspended particles are pushed forward to the mandibles. The mandibles crush the food, after which it enters the intestines.
All organisms and their remains suspended in water serve as food for filter-feeding Calanoida. Crustaceans do not swallow only relatively large particles, pushing them away with their jaws. The basis of nutrition for Calanoida should be considered planktonic algae, consumed by crustaceans in a huge number. Eurytemora hirundoides, during the period of massive development of the alga Nitzschia closterium, ate up to 120,000 individuals of these diatoms per day, and the weight of the food reached almost half the weight of the crustacean. In cases of such excess nutrition crustaceans don’t have time to absorb everything organic matter food, but still continue to swallow it.
To determine the filtration rate of Calanus, algae labeled with radioactive isotopes of carbon and phosphorus were used. It turned out that one crustacean passes through its filtration apparatus up to 40 and even up to 70 per day cm 3 water, and it feeds mainly at night.
Eating algae is necessary for many Calanoida. For example, the reproductive products of Calanus finmarchicus mature only when the crustacean has sufficient consumption of diatoms.
In addition to filter feeders, among Calanoida there are also predatory species, most of which live on significant or large ocean depths, where planktonic algae cannot exist due to lack of light. The hind jaws and mandibles of these species are equipped with strong, sharp spines and are adapted for grasping victims. Particularly interesting are the adaptations for obtaining food in some deep-sea species. Winkstead observed how the deep-sea Pareuchaeta hung motionless in the water, spreading its elongated jaws to the sides, forming something like a trap (Fig. 206). As soon as the victim is between them, the jaws close and the trap slams shut. With the extreme sparseness of organisms at great ocean depths, this method of hunting turns out to be the most appropriate, since the expenditure of energy on active searches for prey is not repaid by eating them.
Rice. 206. Opened "trap" Pareuchaeta
Calanoida is associated with the peculiarities of movement and nutrition complex problem their daily vertical migrations. It has long been noticed that in all bodies of water, both fresh and sea, huge masses of Calanoida (and many other planktonic animals) rise closer to the surface of the water at night, and sink deeper during the day. The scope of these daily vertical migrations varies not only among different types, but even in one species in different places his habitat, in different seasons years and in different age stages of the same species. Often, nauplii and younger copepodite stages always remain in the surface layer, while older copepodite stages and adult crustaceans migrate. In the northern part Atlantic Ocean the vertical migration range of Calanus finmarchicus is 300-500 m. The Far Eastern Metridia pacifica and M. ochotensis cover the same enormous distances every day. At the same time, other widespread Far Eastern Calanoida - Calanus plumchrus, C. cristatus, Eucalanus bungii - migrate no more than 50-100 m.
The speed of movement of crustaceans during their vertical migrations is measured in values of the order of 10-30 cm in a minute. If we take into account the length of their body (for Calanus finmarchicus, for example, about 2 mm), then such a speed must be considered significant. In this case, not only the upward movement, but also the lowering down is carried out due to the active movements of the crustaceans, and not due to their passive immersion.
One should not think that when performing vertical migrations, all crustaceans simultaneously move in any particular direction. The English scientist Bainbridge went underwater and made observations of migrating copepods.
He saw how, in the same layer of water, some crustaceans move up and others move down. Depending on which movement predominates, the entire mass of animals moves up or down.
The question of the reasons for vertical migrations has not yet been fully clarified. It is quite obvious that the desire of crustaceans to rise to the surface layers is explained by the abundance of planktonic algae there, which filter-feeding copepods feed on. Less clear are the reasons that force crustaceans to leave these food-rich layers. Many researchers believe that light has a harmful effect on crustaceans and, avoiding it, they begin to go down in the morning. Important light is confirmed by V. G. Bogorov’s observations of the vertical distribution of copepods in the Barents Sea in summer, i.e., under 24-hour lighting conditions. It turned out that at this time Calanus finmarchicus is invariably located at the same depth, where the lighting conditions are most favorable for it. In this area of the sea, internal waves are observed in the water column, which should either raise or lower the crustaceans somewhat. Obviously, the crustaceans actively move in the opposite direction, since they do not go beyond a certain horizon throughout the day. In autumn, when the cycle of day and night is restored, normal vertical migrations resume (Fig. 207). Not only sunny, but also Moonlight causes crustaceans to move from the surface layers of water to deeper ones.
However, not in all cases can vertical migrations be associated directly with the action of light. There are observations showing that crustaceans begin to descend long before sunrise. Esterly kept the copepods Acartia tonsa and A. clausi in complete darkness, and despite this, they continued to make regular vertical migrations.
According to some scientists, the departure of crustaceans in the morning from the illuminated layer of water should be considered a protective reaction that helps avoid being eaten by fish. It has been proven that fish see every crustacean they attack. Having descended into the deep dark layers of water, the crustaceans are safe, and in the algae-rich surface layers at night the fish also cannot see them. These ideas cannot explain many well-known facts. For example, a number of copepods make regular migrations of short distances, without leaving the illuminated zone and, therefore, remaining accessible to planktivorous fish.
In addition to daily vertical migrations, marine copepods also perform seasonal migrations. In the Black Sea in summer, the temperature of the surface layer rises, and Calanus helgolandicus living there drops by approximately 50 m, and in winter it returns to shallower depths. In the Barents Sea, young stages of C. finmarchicus remain in the surface layers in spring and summer. After they grow up, in autumn and winter the crustaceans move down, and before spring, individuals that reach maturity begin to rise to the surface, where a new generation hatches. Particularly numerous in the surface layers are crustaceans located at the IV-V copepodite stages and known as “red calanus”, as they contain a large amount of brownish-red fat.
"Red calanus" is a favorite food of many fish, in particular herring. Similar character seasonal migrations, i.e., rising into the surface layers of water for reproduction, is found in many other common species, for example, Calanus glacialis, C. helgolandicus, Eucalanus bungii, etc. Females of these species require abundant nutrition of algae for the development of reproductive products, and perhaps in the lighting too. Other species (Calanus cristatus, C. hyperboreus), on the contrary, reproduce in deep layers, and only their juveniles rise to the surface. Adult crustaceans C. cristatus do not feed at all; in sexually mature individuals, the mandibles are even reduced. The length of seasonal migrations is usually longer than daily migrations. The former sometimes cover 3-4 thousand meters, and the latter - at most several hundred meters.
Representatives of the suborder Calanoida are predominantly marine animals. Currently, about 1,200 marine species of these crustaceans are known, belonging to 150 genera and 26 families. Only about 420 species live in fresh waters, distributed among 12 genera and 4 families.
Conducted in Lately detailed studies of the fauna of sea calanids showed that previous ideas about the wide distribution of many species of these crustaceans are incorrect. Each part of the ocean is inhabited mainly by species unique to it. Each species of sea calanids spreads thanks to currents carrying crustaceans. For example, branches of the Gulf Stream entering the Polar Basin bring calanids from the Atlantic Ocean there. In the northwestern part Pacific Ocean in the waters warm current Kuroshio is home to some species, while the waters of the cold Oyashio Current are home to others. It is often possible to determine the origin of certain waters in certain parts of the ocean based on the calanid fauna. Water fauna differ especially sharply in their composition temperate latitudes and waters of the tropics, and the tropical fauna is richer in species.
Calanids live at all oceanic depths. Among them, there is a clear distinction between surface species and deep-sea species that never rise to the surface layers of water. As already indicated, on great depths Predators predominate, and in small areas - filter feeders. Finally, there are species that perform vertical migrations of a huge range, sometimes rising to the surface, sometimes descending to a depth of 2-3 km.
Some shallow-water species of calanids in temperate waters develop in huge numbers and, by weight, constitute the predominant part of the plankton. For example, plankton Barents Sea approximately 90% consists of Calanus finmarchicus (Table 31, 3). These crustaceans are characterized by high nutritional value: their body contains 59% proteins, 20% carbohydrates and often more than 10-15% fats. Many fish, as well as baleen whales, feed mainly on calanids. These are, for example, herring, sardine, mackerel, anchovy, sprat and many others. One herring was found to contain 60,000 copepods in its stomach. The whales that actively consume huge masses of calanids are fin whales, sei whales, blue whale and humpback.
Calanoida of inland waters resemble marine species in their biology. They are also confined only to the water column, also perform vertical migrations and feed in the same way as marine filter feeders. They live in a wide variety of water bodies. Some species, such as Diaptomus graciloides and D. gracilis, live in almost all lakes and ponds in the northern and central parts of the USSR. Others are confined only to the Far East or to the southern part of our country. The distribution of Limnocalanus grimaldii, which inhabits many lakes in the north of our country (including Onega and Ladoga) and Scandinavia, is very interesting. This species is close to the coastal brackish-water L. macrurus, which lives in the pre-estuary spaces of northern rivers. The lakes inhabited by L. grimaldii were once covered by the cold Ioldian Sea. In Baikal, the crustacean Epischura baicalensis, unique to this lake, lives in huge numbers and serves as the main food for omul. Very peculiar, although still little known, are the conditions of existence of the recently discovered only underground representative of calanids - Speodiaptomus birsteini.
This blind crustacean was found in the deep and narrow water-filled crevices of the lower floor of the Skelskaya Cave, located in the Crimea, near Sevastopol. We were able to observe him in an aquarium, and it turned out that he swims just like ordinary freshwater calanids. It remains a mystery what it feeds on as it filters the clean, completely algae-free and probably very bacteria-poor underground pool water. Apparently, it can be considered the only true underground planktonic animal.
Some freshwater calanids appear in water bodies only at certain times of the year, for example in spring. In spring puddles one often finds relatively large ones (about 5 mm) Diaptomus amblyodon, colored bright red or Blue colour. This species and some other widespread freshwater calanids are capable of forming resting eggs that can withstand drying and freezing and are easily carried by the wind over long distances.
Suborder Cyclops (Cyclopoida)
Another suborder of copepods - Cyclopoida - the largest number species are present in fresh waters.
Freshwater cyclops live in all kinds of bodies of water, from small puddles to large lakes, and are often found in very large numbers of specimens. Their main habitat is the coastal strip with thickets of aquatic plants. Moreover, in many lakes, thickets of certain plants are associated with certain types Cyclops. So, for example, for Valdai Lake in Ivanovo region 6 groupings of plants with their corresponding groupings of Cyclops species are described.
Relatively few species can be considered true planktonic animals. Some of them, belonging mainly to the genus Mesocyclops, constantly live in the surface layers of water, others (Cyclops strenuus and other species of the same genus) make regular daily migrations, descending during the day to a considerable depth.
Cyclops swim somewhat differently than calanids. Simultaneously flapping four pairs of thoracic legs (the fifth pair is reduced), the crustacean makes a sharp jump forward, upward or sideways, and then, with the help of the front antennae, can hover in the water for some time. Since the center of gravity of its body is shifted forward, while hovering its front end tilts and the body can assume a vertical position, and the dive slows down. A new swing of the legs allows the Cyclops to rise. These swings are lightning fast - they take 1/60 of a second.
L. Isaev, who has been extensively involved in the biology of cyclops, describes their movements as follows: “Moving in rhythmic leaps, a cyclops can stay well at one level, rise up and fall down at angles of varying steepness. A cyclops can swim with equal ease, turning over on its back. The cyclops describes well arcs, makes dead loops, single and multiple, direct and reverse. The Cyclops can make a turn at an angle of 90°, rotate around an axis not only with a descent, reminiscent of the turns of an airplane “corkscrew,” but also with an upward movement. make a flip through it, dive upside down at an angle of 90° and slide onto the tail. The nature of the “figures” performed by the Cyclops is very similar to aerobatic maneuvers. Possessing the aerobatic maneuvers necessary for fighter aircraft undoubtedly makes it easier for the Cyclops, an active predator. - the ability to ensure one’s existence by hunting for aquatic inhabitants serving him as food."
Most cyclops are predators, but there are also herbivorous species among them. Such common, widespread species as Macrocyclops albidus, M. fuscus, Acanthocyclops viridis and many others quickly swim above the bottom or among thickets in search of prey. With the help of their antennae, at a very short distance, they sense small oligochaetes and chironomids, which they grab with their front jaws armed with spines. The hind jaws and maxillae are involved in transferring food to the mandibles. The mandibles make rapid cutting movements for 3-4 seconds, followed by a minute pause. Cyclops can eat oligochaetes and chironomids larger than themselves. The speed at which prey is eaten depends on their size and the hardness of their coverings. For crushing and swallowing bloodworms 2 long mm it takes 9 minutes, and the larva is 3 long mm destroyed within half an hour. More delicate, although longer (4 mm), the Nais oligochaete worm is eaten in just 3.5 minutes.
Herbivorous cyclops, in particular the common Eucyclops macrurus and E. macruroides, feed mainly on green filamentous algae (Scenedesmus, Micractinium), capturing them in approximately the same way as predatory ones capture worms and bloodworms; in addition, various diatoms, peridinia and even blue-green algae are used. Many species can only eat relatively large algae. Mesocyclops leuckarti quickly fills its intestines with Pandorina colonies (colony diameter 50-75 mk) and almost does not swallow small Chlamydomonas at all.
Freshwater cyclops are very widespread. Some species are found almost everywhere. This is facilitated primarily by adaptations to endure unfavorable conditions, in particular the ability of crustaceans to tolerate drying out of water bodies and passively disperse through the air in the form of cysts. The skin glands of many cyclops secrete a secret that envelops the body of the crustacean, often together with the egg sacs, and forms something like a cocoon. In this form, crustaceans can dry out and freeze into ice without losing their viability. In Camerer's experiments, cyclops were quickly hatched by soaking dry mud, which was preserved for about 3 years. Therefore, there is nothing surprising in the appearance of cyclops in spring puddles that appear when snow melts, in newly filled fish ponds, etc.
The second reason for the wide distribution of many species of Cyclops should be considered the resistance of crustaceans located in active state, in relation to the lack of oxygen in water, its acidic reaction and many other factors unfavorable for other freshwater animals. Cyclops strenuus can live for several days not only in the complete absence of oxygen, but even in the presence of hydrogen sulfide. Some other species also tolerate unfavorable gas conditions well. Many cyclops thrive in water with an acidic reaction, with a high content of humic substances and extreme poverty of salts, for example, in reservoirs associated with high-moor (sphagnum) bogs.
Nevertheless, species and even genera of Cyclops are known that are limited in their distribution by certain certain conditions, in particular temperature and salt conditions. For example, the genus Ochridocyclops lives only in Lake Ohrid in Yugoslavia, the genus Bryocyclops - in Southeast Asia and in equatorial Africa. Close to the last genus is the exclusively underground genus Speocyclops, species of which are found in caves and groundwater Southern Europe, Transcaucasia, Crimea and Japan. These blind small crustaceans are considered remnants of a once more widespread thermophilic fauna.
Some Cyclops have adapted to life in brackish and even very salty bodies of water. The genus Halicyclops, for example, is quite common in the Caspian Sea and is not found in fresh water. Microcyclops dengizicus is widespread only in brackish and saline reservoirs of the desert zone (Iraq, India, Haiti, Egypt, California, in the USSR - in the Karaganda region, in the Mugan steppe) and lives well even at salinities exceeding sea salinity (up to 41 0 / 00). Many common freshwater species can also exist in brackish water, such as Mesocyclops leuckarti in the Gulf of Finland and the Gulf of Bothnia.
Marine representatives of the suborder Cyclopoida are less diverse than freshwater ones. Among them, species of the genus Oithona are common and often numerous in marine plankton. Large ones are also very typical (up to 8 mm) flattened species of the genus Sapphirina, the surface of the body of which is cast in bright blue, golden or dark red tones (Table 31, 1). Another close marine genus - Oncaea (Table 31, 4) - has glands that secrete a luminous secretion, and often, together with other organisms, causes the sea to glow.
Suborder Harpacticoida
Much less is known about the lifestyle of representatives of the third suborder - Harpacticoida. These worm-like, mostly very small crustaceans, are extremely diverse in both marine and fresh waters, but are never found in large numbers. More than 30 families and several hundred species of Harpacticoida have been described.
Most harpacticids crawl along the bottom and bottom plants. Only a few species are capable long time swim and are part of marine plankton (Microsetella). Much more typical are entire groups of genera and species of harpacticids, adapted to living in special, unusual conditions, in particular in the capillary passages between grains of sand on sea beaches and in underground fresh waters.
Just a few years ago, zoologists used a very simple technique to study the population of the capillary passages of sea sand. A hole is dug on the beach, above sea level. Water gradually accumulates in it, filling the capillaries of the sand. This water is filtered through a plankton network and thus representatives of a peculiar fauna, called interstitial, are obtained.
Harpacticides constitute a significant part of the interstitial fauna. They were found everywhere where relevant research was carried out - on the beaches of England, along the European and American coasts of the Atlantic Ocean, on the Mediterranean and Black Seas, off the coast of Africa and India, on the islands of Madagascar, Reunion and the Bahamas. Most interstitial harpacticids belong to special genera that live only in such conditions, distinguished by an unusually thin and long body (Fig. 209), allowing the crustaceans to move in narrow capillary passages. It is remarkable that some of these specialized species were found in very widely separated places. For example, Arenosetella palpilabra, previously known only from Scotland, and Horsiella trisaetosa, previously known only from Kiel Bay, were found in the Bahamas. It is difficult to explain such a distribution, since interstitial harpacticids do not have resting eggs.
Harpacticides of fresh groundwater are also represented by a number of specialized genera - Parastenocaris, Elaphoidella, Ceuthonectes and others, partly very widespread, partly having narrow and fragmented habitats. For example, two species of the genus Ceuthonectes live only in caves in Transcaucasia, Yugoslavia, Romania, Italy and Southern France. These widely separated locations are believed to be the remnants of what was once a much larger area of distribution of the ancient family. In some cases, the tropical origin of the underground harpacticides of Europe can be assumed. Among the numerous species of the genus Elaphoidella there are both tropical and European species. The former live in terrestrial areas, the latter (with a few exceptions) in groundwater. In all likelihood, the remains of an ancient tropical fauna, perished on the surface of the earth under the influence of climate change. In tropical terrestrial water bodies, some harpacticids are adapted to living conditions that resemble those in groundwater. Tropical species of Elaphoidella are known to live in peculiar micro-reservoirs formed in the leaf axils of aquatic plants from the Bromeliaceae family. The tropical Viguierella coeca, found on these plants in botanical gardens in almost all countries, lives in the same conditions.
The peculiar fauna of Baikal is extremely rich in species of harpacticids. It consists of 43 species, of which 38 are endemic to this lake. There are especially many of these crustaceans in the coastal part of Lake Baikal, on rocks and aquatic plants, as well as on the sponges growing here. Apparently, they feed on sponges and, in turn, become victims of the amphipod Brandtia parasitica, which also crawls on the sponges.
Some types of harpacticids are confined only to reservoirs that are very poor in salts, characterized by high acidity, i.e., associated with high-moor, sphagnum, and bogs. Such is, for example, Arcticocamptus arcticus, the biology of which was studied in detail by E. V. Borutsky.
A. arcticus is widespread in northern Europe, from the Bolynezemelskaya tundra to Scandinavia, on west coast Greenland, on Novaya Zemlya. In addition, it is found in the Alps and at several points middle zone The European part of the USSR, including in Kosin near Moscow, in Zvenigorod, near Yaroslavl, etc. Everywhere it lives in reservoirs associated with sphagnum bogs.
Of the numerous reservoirs located near Kosin, the crustacean lives only in two swamps and in the Holy Lake, which lies among the sphagnum peat bog. Obviously, the living conditions in various other neighboring water bodies are unfavorable for A. arcticus. Moreover, even in the few reservoirs inhabited by it, the crustacean exists in an active state only for 1 1/2 -2 months in the spring; the rest of the year, i.e. 10-10 1/2 months, it spends in the resting egg stage.
The life cycle of A. arcticus is closely linked to change vegetation cover swamps. E.V. Borutsky writes: “As soon as the loose snow begins to melt with the first warm rays of spring and puddles form on the surface of the swamp, all animals that have spent a harsh winter in one or another stage in icy confinement begin to react to the first spring rays. A. arcticus is one of the first to emerge from the state of suspended animation and appear in the reservoir. Already in small puddles, still among the snow, where the surface layers of sphagnum have thawed, you can find its larvae, slowly and clumsily moving among the leaves of moss in search of food. The larvae are in the first nauplial stage and have apparently just hatched from the egg. Every day the nauplius grows stronger, its movements become more confident and faster, and finally the moment of the first molt comes - it exchanges the old narrow shell for a new, more spacious one. The first moult is followed by the second, third, etc., and after two to three weeks we already meet adult specimens or larvae at the last copepodite stage. But they no longer enjoy the space that they had in their early larval state: instead of vast puddles full of water, in which they freely swam from one sphagnum bush to another, there is now only wet moss and a small amount of water. Instead of pitiful bare branches there are now delicate pink flowers of Cassandra and cranberries, white cups of andromeda and the caps of blooming blasphemy. The swamp has changed - the bright green sphagnum carpet is replete with pink and white spots of flowers. And this change in the picture of the swamp perfectly coincides with a certain moment in the biology of A. arcticus, namely the period of copulation. For several days we meet almost exclusively copulating couples. But these flowers are fatal for A. arcticus: with their gradual withering, a gradual decrease in the number of crustaceans is observed, copulation occurs less and less often, females with egg sacs are more often encountered, and, finally, by the middle or end of June, A. arcticus completely disappears from the reservoir , and only belated specimens are found in small quantities in July or early August."
The crustacean leaves its egg sacs in the reservoir, which have the shape of two balls connected together, covered with a common “sac” shell, which mechanical protection eggs, and also protects them from drying out. In addition, each egg has its own thinner transparent shell. It is impermeable to both salts and water. By autumn, a nauplius is formed in each egg, and the nauplii of two connected eggs are always directed with their anterior ends in opposite directions. Nauplii are covered with another very thin and elastic inner shell, equipped with various cords and threads. This shell is permeable to water, but not to salts.
When the time comes for the nauplii to hatch, i.e., during the spring melting of the ice, a crack forms in the sac shell on one side, through which the elastic inner shell begins to protrude. At first, this process goes very slowly, but after about half of the larva surrounded by the shell is outside, a sharp push occurs and the larva, enclosed in a hollow ball, seems to “shoot” out of the egg sac and bounces to the side or is held behind the edges of the slit by elastic appendages. shells. It is remarkable that the nauplius itself remains completely passive almost all the time. Only at the very beginning of the hatching process does the nauplius make several rather weak movements, apparently leading to rupture of the egg membrane. The main role here is played by a semi-permeable elastic shell, through which water diffuses, causing it to swell, which first causes the sac shell to burst, and then the nauplius, surrounded by an elastic shell, to bulge out of it. The strands and threads of this shell act like springs, and they are located in such a way that the nauplius inside the hollow ball formed by the shell always comes out with its head end forward. Behind the first nauplius, through the same gap in the sac shell, the second one protrudes in the same way, or both “shoot” at the same time. The first impetus for swelling of the elastic membrane is, apparently, the rupture of the egg shell by the nauplius (Fig. 210).
Only after some time does the newborn nauplius, located inside the completely inflated elastic shell that has taken on a spherical shape, begin to move and try to tear it apart. He does not succeed immediately, after which the shell collapses and the larva is free. Tired of hard work, at first she is almost unable to move quickly, but she does not need this, since she finds a sufficient amount of food on the surface of the just abandoned sac shell, which usually overgrows with algae and becomes covered with detritus particles during its many-month stay in the reservoir.
When A. arcticus eggs were placed in water from reservoirs unfavorable for its existence, the nauplii inside the eggs developed normally, but they did not hatch. Through special experiments, E.V. Borutsky proved that with a relatively high salt content in water, water does not diffuse through the elastic inner shell and it does not swell.
If the water is not acidic, the egg shell does not partially dissolve or soften, which also eliminates the possibility of the nauplius hatching. Thus, both of these shells prevent the nauplius from hatching when the egg gets into conditions unfavorable for the crustacean, dooming it to death. Indeed, larval stages and adult crustaceans died in the water of lower (non-phagnum) bogs, as well as other bodies of water, containing the usual amount of salts and having a neutral or alkaline reaction. All this makes clear the strict confinement of A. arcticus to raised, sphagnum, bogs with their specific hydrochemical regime.
If A. arcticus exists in an active state in the spring, then some other species of freshwater harpacticids are found only in winter or only in summer. At the same time, species are known that spend the resting period not in the resting egg stage, like A. arcticus, but in the cyst stage, somewhat reminiscent of the Cyclops cysts described above. In Canthocamptus staphylinus such cysts are round, in Attheyella wulmeri and A. northumbrica they are oval, with the furcal bristles of the crustacean protruding from the shell (Fig. 211).
Among freshwater harpacticids, there are species capable of parthenogenetic reproduction, which is not characteristic of all other copepods. In Elaphoidella bidens, which is widespread in Europe, males are generally unknown, but under experimental conditions, 5 generations of parthenogenetic females were obtained from this species. Epactophanes richardi also turned out to be capable of parthenogenetic reproduction, although under natural conditions it is represented by both females and males. Apparently, some other species of harpacticids can reproduce parthenogenetically.
The practical importance of harpacticids is incomparably less than that of calanids and cyclops. In some reservoirs they constitute a significant part of the food of fish, especially their juveniles.
Ergasilus larvae emerging from eggs lead a free lifestyle. After 2-2 1/2 months, the crustaceans reach maturity and mate. Fertilized females actively move against the current. This helps them settle on the gills of fish, because from under operculum the flow of water is directed.
In the same way, the gills of fish are affected by glochidia of pearl barley (see above). It is interesting that there is antagonism between ergazilides and glochidia: one displaces the other and is not found together on the gills of the same fish.
Here the nauplius molts, turning into a multicellular oval body. Subsequently, this embryo develops two long appendages at the anterior end, which serve to absorb food. The embryo molts again and transforms into a long, sausage-shaped body, inside which an adult crustacean with well-developed genitals is formed. He breaks through the wall blood vessel and integument of the host and begins active existence (Fig. 213).
Representatives of the suborder Caligoida are characterized by an expanded body, flattened in the dorso-abdominal direction, segmentation of the thoracic region is lost to one degree or another, females have a very large anterior abdominal (genital) segment, to which two egg sacs are attached, the oral appendages form a proboscis, which allows them to suck blood owner. Females and males differ little in size and structure.
Cyclops differ from Diaptomus in a number of features. The anterior part of the body consists of a head and three thoracic segments; the abdomen of females consists of five segments.
Antennae short, no longer than two-thirds of the anterior part of the body. Both antennules of males are transformed into geniculate organs. Antennae single-branched, without exopodites. Thoracic legs of the first four pairs with tripartite endopodites and exopodites. The legs of the fifth pair are vestigial, of the same structure in both sexes. The heart is missing. Females carry eggs in two egg sacs attached to the sides of the genital segment. Currently, the former genus Suslops is divided into several new genera (Cyclops s. str., Macrocyclops, Eucyclops, Mesocyclops, Acanthocyclops, etc.).
Most common species Cyclops differ from each other the following signs(the table is based on the structure of the legs of the fifth pair in females).
The last leg segment of the fifth pair of stirrups is appendages.
Antennales 17-segmented.
A plate along the edge of the last antennular segment with deep notches - Mesocyclops fuscus
The indicated plate is smooth - Mesocyclops albidus
Antennales 12-segmented
The outer edges of the furcal branches are armed with large spines - Eucyclops serrulcitus
The outer edges of the furcal branches are smooth, with one group of spines - Eucyclops macrurus
The indicated segment with two appendages
Last leg segment of the fifth pair with one long and one short spine
The first segment of the legs of the fifth pair is wide - Acanlhocyclops viridis
The indicated segment is narrow, cylindrical
The lateral posterior angles of the last thoracic and first abdominal segments are short - Cyclops strenuus
The lateral posterior angles of the last thoracic segment and the first abdominal segment are elongated into long pointed processes of Cyclops vicinus
Indicated segment with two long setae
Along the last segment of the antennules there is a plate with a deep notch - Mesocyclops leuckarti
There is no plate on the last segment of the antennae
The last endopodite segment of the legs of the fourth pair is armed with one short and one long spine Mesocyclops oithonoides
The indicated segment is armed with two short, almost equal-length spines - Mesocyclops dybowskii
Observations of the movement of copepods are made as follows. Place several living specimens of diaptomus or cyclops in a narrow glass vessel with parallel walls. After some time, when the animals calm down, their movements are observed through a strong, large-diameter magnifying glass. The trajectory of the movement can be sketched on checkered paper by placing another sheet of checkered paper behind the aquarium.
In a state of soaring, diaptomuses hang on outstretched antennules, which, due to their length and large number of setae, present significant resistance to water. The slow descent, which continues in diaptomuses until the body drops a few centimeters, is replaced by a sharp jump, directed obliquely upward and caused by synchronous impacts of the pectoral (swimming) legs and abdomen; During the jump, the antennules are pressed against the body and do not participate in the movement. By the end of the ascent, the longitudinal axis of the animal is horizontal. Then the antennules straighten, and the organism hanging on them returns to its original position. In addition to this method of movement, diaptomuses can slowly slide for a long time at the same level in a spiral or in a circle. The organs of movement in this case are the antennae, mandibular palp and maxillulae, the impacts of which cause a strong current of water; The antennules play the role of rudders.
Cyclops are swimmers. Their abdomen is relatively longer than that of Diaptomus; antennules short. The movements of the Cyclops, which have the nature of “jumping”, are caused mainly by the blows of the pectoral (swimming) legs. Both legs of each pair are connected to each other by a chitinous plate, so they move simultaneously; with a quick kick of the legs, the cyclops make impetuous jumping movements that can be directed in any direction. As soon as the swimming legs stop working, the cyclops quickly sink down, taking on an almost vertical position.
What does a person imagine when he hears a word? "Cyclops"? As a rule, there are two options: if he is far from biology and aquarium hobby, then, most likely, he will decide that we're talking about about the mythical one-eyed giant who threw stones at the ships of Odysseus. If the subject in question has an aquarium or carefully read biology at school, then for him the Cyclops, first of all, will look like a tiny crustacean, upon closer examination, much more mysterious and terrible than the mythical giant.
Several times I came across cyclops while studying silt from an aquarium, however, these crustaceans are rare guests in an aquarium. The real dominance of cyclops was discovered in water from stagnant shallow waters. These crustaceans stood out among the other zooplankton swarming in the bowl with their striking bright green (almost fluorescent) color. What they ate to achieve such an effect remains a mystery to us.
Who are the Cyclops?
Well, Firstly, this is a popular fish food, along with gammarus, but this aspect of their life (more precisely, death) is of little interest, so we will not dwell on it.
Secondly, these are small (0.6-6 mm) crustaceans belonging to the order copepods.
Classification of Cyclops
Not everything is clear with the classification of Cyclops. So, according to Wikipedia it looks like this:
- Type: Arthropods
- Subtype: Crustaceans
- Class: Maxillopods
- Subclass: Copepods
- Squad: Cyclops
- Family: Cyclops
That is, here, shaking the foundations of my worldview, crustaceans are not a class, but a subtype. Copepods are classified as a subclass maxillopods. In general, perhaps it is more correct and more modern, but for simple amateurs who do not go into the taxonomic jungle, it is easier to rely on the old classification (TSB), so at least there is a chance to remember:
- Type: Arthropods(Arthropoda)
- Class: Crustaceans(Crustacea)
- Squad: Copepods(Copepoda)
- Family: Cyclops(Cyclopidae)
- Genus: Cyclops
- View: Cyclops coronatus
The structure of the Cyclops
Where did the name come from "Cyclops" It’s not difficult to guess - our hero has only one eye, but he has enough.
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The body of the Cyclops is divided into a cephalothorax and abdomen. In front there are two pairs of branched antennae (of course, not nearly as branched as those of). On the underside of the abdomen there are 4 pairs of developed rowing legs. The fifth pair in males is transformed into a special grip for holding the female during mating. The female has paired egg sacs on the sides of her abdomen.
In comparison with, the internal structure of the Cyclops looks simplified. It has neither a heart nor gills. There is no circulatory system: the organs are washed by hemolymph, moving due to the pulsation of the intestines. Absorption of oxygen from water occurs over the entire surface of the body.
Unlike Daphnia, Cyclops reproduce sexually. Most sources say that parthenogenesis is not observed in copepods.
Cyclops habitats
Cyclops are ubiquitous and have proven themselves to be one of the most hardcore survivalists. They live in winter reservoirs under a crust of ice, in acidic and hot springs, in waters with an insignificant oxygen content and lethal amounts of hydrogen sulfide, in general, almost everywhere.
When a body of water freezes or dries out, Cyclops “preserves” itself by secreting special substance, forming a kind of cocoon around the crustacean. In such a cocoon, Cyclops can freeze into ice or remain at the bottom of a dry puddle. Experiments were carried out in which cyclops were preserved in dry silt, which had lain without water for three years.
By nature of feeding, Cyclops is a predator. It feeds on rotifers, small crustaceans, in general, everything it can catch.
Cyclops is an extremely fast creature. Its movements are so rapid that it is almost impossible to catch it through the lens of a camera or microscope without first immobilizing it.
Cyclops (Cyclops coronatus), side view
When there comes a short moment of peace and focus on it, it still turns out that the restless crustacean takes off exactly 1/100 of a second before pressing the shutter button. Also, it is not always possible to suck it up with a syringe the first time, which turns the process of catching a Cyclops for study into a real safari.
In the following photos taken through microscope, Cyclops are shown from the side, covered with colonies of ciliates. Although the individuals were still alive, their end was not far off: such a number of sticks attached usually indicates the imminent end of the carrier.
Cyclops and the Suvoyki
The rowing legs are clearly visible here. Due to the shape of the Cyclops, most images (including textbooks) show the crustacean from the back.
Half-dead female cyclops, covered with souvoikas
That's probably all I can say about the Cyclops.
If you have read this article, I recommend that you also read it, because. Cyclops and Daphnia are almost always mentioned side by side as one of the most common inhabitants of our water bodies.