Order beak-headed (Rhynchocephalia)
Wedge-toothed family (Sphenodontidae)
|Hatteria (Sphenodon punctatus)|
In all respects, this remarkable detachment of beak-headed lizards is completely similar in appearance to lizards, but in its internal structure it combines the characteristics of various other orders, even classes, with some of the strangest features, in a certain respect it is similar even to amphibians. The related tuatara combines the features of primitive stegocephals, the remains of which are found in the Permian and Devonian formations of Bohemia and Saxony, with signs of extinct plesiosaurs and our common lizards.
Tuberculosis (Sphenodon punctatus), we must consider a type of a special family and a representative of the order of beakheads, equivalent to and significantly different from groups of lizards, snakes, crocodiles and turtles. It is a large, somewhat awkward animal, resembling the body shape of some iguanas.
The head is tetrahedral, the body is shortened, the limbs are strong, the tail is approximately equal to the length of the body, the tail is compressed, triangular *, the front and hind legs each have five strong, short, rolling toes with small membranes and short claws.
* The tail of the tuatara is capable of regeneration.
There are no thigh pores. On the neck, along the middle of the back, as well as along the middle of the tail, a ridge, interrupted in the shoulder and lumbar region, rises, consisting of flat spines. Small scales cover the head, smaller ones, mixed with larger ones - the body, large quadrangular flat scutes located in transverse rows - the lower side, small scales - the tail, the upper and lower sides of the fingers. The scales of the entire upper side are grainy, those that cover the irregular folds of the skin are larger than the rest.
The main color is pale olive green, the sides and limbs are speckled with small white and larger yellow specks lying between them, the spines of the ridge on the neck and back are yellow, the spines of the caudal ridge are brown.
Much more remarkable and important features are found in the anatomy of this animal. The square bone, in contrast to what we find in all scaly reptiles, is motionlessly connected to the skull, the facial part of the skull is connected to the temporal region by two bony bridges passing over the temporal fossa.
The teeth are strengthened in the usual way by their roots at the edge of the jaw bones, but, with the exception of the also changing, but not disappearing, two large front teeth, they are so worn out in older animals that they must, like turtles, bite with the edges of the jaws. At the outer edge of the palatine bones is the second row of teeth. When the mouth is closed, the row of teeth of the lower jaw falls between the palatine and the parallel maxillary row of teeth. On each coulter there are sometimes one or two teeth.
The branches of the lower jaw are connected in front by a ligament, like in snakes. The vertebrae are provided with funnel-shaped depressions anteriorly and posteriorly, as in some amphibians and many teleost fishes, and as was the case in fossil reptiles - ichthyosaurs, megalosaurs, and teleosaurs. Equipped with one articular head, ribs with hooked processes are similar to those of most lizards in that some of them, namely three pairs, are connected to the sternum, and then there are eleven pairs of false ribs.
But the lower ends of the false ribs are connected, in turn, with special narrow bones, abdominal ribs, which lie in the subcutaneous layer of the abdominal integument and in their number and position correspond to the external abdominal plates located in transverse rows and double the number of vertebrae and false ribs. They are so tightly connected to the abdominal plates that they can only be separated from them with a knife. The transverse row of the abdominal scutes of this animal corresponds, therefore, to the separate abdominal scutellum of the snake and even more separate parts of the abdominal carapace of the turtle.
The content of hilodus in the aquarium
For content hilodus an aquarium from 80 liters, decorated in the style of a "rainforest aquarium", is suitable.
Fish thrive both in relatively hard (12-15 dGH) and soft (1.5-2 dGH) water, with an active pH reaction from 6.0 to 7.0 units.
The optimum water temperature for keeping chylodus is 24-25 ° C. Fish, without any consequences, tolerate a short-term decrease to 18-20 ° C.
Thickets of aquatic plants should be combined with open spaces. Lighting is selected depending on the requirements of the plants. The luminaires are installed so that only a certain part of the aquarium is brightly lit, while the other remains in the shade. Floating and long-stemmed plants can act as shades.
Hilodus have a peaceful disposition, therefore they are suitable for keeping in a common (mixed) aquarium.
Since the fish are schooling, they should be kept in the aquarium in a group, preferably at least 10 individuals. Any peaceful medium-sized fish species can be their neighbors.
In aquarium hylodus keep in the lower and middle layers of water, hovering head downward, only from time to time in search of food sinking to the bottom.
The diet of the hilodus
In the aquarium, the diet hilodus consists of live or frozen food: bloodworms, tubifex, daphnia and cyclops.
Moreover, they eat the tubifex and daphnia more willingly than bloodworms and cyclops. Along with live food, food of plant origin is of great importance in their diet. Fish happily eat delicate light green leaves of soft-leaved aquatic plants and finely chopped lettuce leaves.
Sexual dimorphism is weak. Males are smaller and slimmer than females, with a large number of dark spots on the dorsal fin. The length of males is usually 6.5-7 centimeters, females 8-9 centimeters, although in nature the fish grow up to 10-12 cm. In females, the abdomen is noticeably fuller than in males.
A pair of hilodus: female at the top, male at the bottom
Breeding hilodus in an aquarium
Dilute hilodus few succeed. In Russia, they were first divorced in 1966 in Moscow.
Sexual maturity in hilodus occurs upon reaching the age of 8-10 months. Spawning can be both paired and group.
For breeding hilodus, from the group of sexually mature individuals, future producers are selected: females with a full abdomen and mobile, not too lean males. The best result is obtained by using two-year-old females and one and a half-year-old males.
The success of breeding largely depends on the selection of producers and their preliminary preparation.
Selected producers are seated in different containers or separated by an opaque partition. For one to two weeks, they are fed abundantly and variedly with animal and vegetable (scalded lettuce, oatmeal) food. During this period, you should not change the water and increase its temperature, above the value at which the fish were kept before.
A container of 20 liters with a bottom area of 1600 to 2000 cm2, without soil, filled with water to a level of 20-25 cm is suitable as a spawning grounds.Water is prepared by mixing aquarium water with distilled water until a total hardness of 2 to 3dGH is obtained, with the addition of peat extract or using peat filler in the filter.
The active reaction of water in the spawning grounds should be in the range of 5.0-6.5 units. It is recommended to cover the spawning box from the sides from light.
After the broodstock have been planted, the temperature in the spawning box is raised by 2-3 ° C higher than that at which the fish were kept.
At the bottom of the spawning box, a separator mesh (with cells of more than 2 mm) is installed, covering two-thirds of the bottom. In the center of the grid, a spawning substrate is fixed, which can be a bunch of small-leaved plants, willow roots, or synthetic threads.
Overhead lighting, diffused, weak.
Pre-spawning grounds and substrate are thoroughly disinfected.
Producers are planted for spawning in the evening so that they can settle in a new place during the night.
Hilodus spawn during daylight hours, as a rule, during the day. It is advisable not to disturb them at this time. Spawning is stimulated by daily replacement of 1/5 of the volume of water with fresh soft water. Such a technique will have a positive effect on the quality of caviar in the future.
Usually spawning occurs the next day, but sometimes it is delayed up to three days, in which case the producers have to feed.
It is for this case that a third of the bottom remains free of the separator mesh. After feeding, food residues and fish excrement should be removed immediately.
During spawning games, producers take a horizontal position. Their color changes noticeably: the dark longitudinal stripe and dark tones on the dorsal fin disappear. Pea-sized spots appear under the operculums, and the anal and adipose fins become dark.
At the initial stage, the male pursues the female, trying to snuggle up to her with his whole body, spreading his fins, and circles around her.
At the next stage, the partners are already circling together, located parallel to each other. Spawning occurs near the substrate, in the immediate vicinity of the bottom.
Spawning lasts about 2 hours, after which the activity of producers decreases. The black spot behind the operculum disappears, and a longitudinal black stripe appears along the lateral line of the body.
The productivity of females, depending on age and size, ranges from 100 to 500 eggs.
Overall spawning hilodus very similar to spawning hifessobricons.
Caviar is brown, about 1 mm in diameter. After a couple of hours, it swells to a size of 3 mm.
At the end of spawning, the eggs are transferred to another smaller container filled with water to a level of 5 cm, with the same parameters and an operating air compressor.
The masonry is periodically inspected, removing dead whitened eggs with a glass tube.
On the fourth day, it is already possible to distinguish formed embryos in the eggs.
By the end of the incubation period, and this happens depending on the temperature of the water, on the fifth - seventh day, the shell of the eggs loses its strength, the larvae break through it and go outside.
If the exit of the larvae is not friendly, then the larvae should be helped, but not with the help of a needle, as some authors advise, but by increasing the water temperature by 2-3 ° C, while increasing aeration. After such a reception, after 30-40 minutes, a friendly hatching usually occurs.
The shell of eggs in too hard water does not lose its strength, hence there are problems with hatching.
In water with a temperature of 26-27 ° C, c 0 dGH and pH 5.5, the larvae hatch well.
After hatching is complete, aeration is reduced. From the first hours of life, the larvae assume the same position as the adult fish. The fry are large, up to 10 mm and transparent. Live dust and brine shrimp nauplii serve as a starting food for them. As the fry grow, the size of the feed is proportionally increased.
Hilodus grow quickly, but not always evenly, after two weeks some specimens reach a length of 1.5 cm. In this regard, cannibalism is sometimes observed among the fry. Juveniles hilodus very sensitive to water quality. Therefore, a filter should be installed in the growing aquarium. At the age of 7-8 weeks, juveniles are 2-2.5 centimeters in size and acquire the color of adult Chylodus.
Once a pair has spawned, it is not recommended to separate it in the future.
If for some reason the couple did not spawn, you can try flock breeding. In this case, the volume of the spawning box is increased to 100-150 liters. A group of fish consisting of 8-12 individuals is planted for spawning. The water parameters are the same as for pair dilution. It is desirable that the space free from the net occupies about 50% of the bottom area. Moreover, this part of the spawning ground should be illuminated less intensely than the one where the bottom is covered with a separator mesh. With this light mode, the flock will be in a dimly lit area.
Couples, ready for spawning, will alternately swim up to the substrate fixed in the center of the net, sweeping out a portion of eggs. The rest of the pack never interfere with the spawning pair.
If the size of the aquarium allows, several pairs can spawn at the same time.
After the end of spawning, eggs are transferred to an incubator. And the fish participating in spawning are transplanted into a common aquarium.
Hilodus - fish for experienced aquarists, as they are very sensitive to water quality.
Currently hylodus rarely found in hobbyist aquariums, due to the complexity of their breeding.
Chilodus, the scientific name Chilodus punctatus, belongs to the Chilodontidae family. From common English names, this species is translated as "standing on the head" because of the unique way of movement. He spends most of the time with his tail raised above his head, thus holding his body not horizontally, but at an angle.
Difficult enough for keeping and breeding in a home aquarium, and almost beyond the capabilities of novice aquarists. Requires high quality water of a certain composition, but if you can solve this problem, then the flock of Hilodus will become a real sparkling treasure of your aquarium.
- Size - up to 8 cm. Food - any
It is widely distributed in the upper reaches of the Amazon River basin (South America) on the territory of modern Ecuador, Peru and Brazil, as well as in the Orinoco river system in Colombia. Inhabits slow-moving streams and rivers, tributaries, floodplain lakes, flooded areas of the forest.
A slender graceful fish, the back has a pronounced rise, topped with a dorsal fin. The tail is clearly divided into two parts - a petal. The color is silvery with numerous dark specks, in the center they are most densely located, thereby forming a horizontal line. The specks continue on the fins, which are generally transparent, but sometimes have a reddish tint. Sex differences are weak. In males, the dorsal fin is slightly higher than in females, which in turn have a more rounded shape.
The diet should consist of a variety of foods that combine meat and vegetable components. Bloodworms, daphnia, brine shrimp with addition of pyrulina flakes, small pieces of cucumber, lettuce, some fruits typical of the upper Amazon.
Experienced aquarists are allowed to experiment with the diet only, for the rest it is more advisable to purchase specialized high-quality food from reputable manufacturers.
Maintenance and care
A school of fish needs a spacious tank, for 10 individuals at least 200 liters. In the design, it is necessary to achieve a balance between free areas and dense thickets of plants in a ratio of 50 to 50. Floating plants are welcome, they are assigned the role of shading part of the aquarium. The substrate is sandy, on which various shelters of driftwood, branches and / or tree roots are located. A few dried leaves can be lowered to the bottom; in the process of decomposition, they saturate the water with tannins and lightly color it, which is characteristic of the natural habitat of the Hilodus. The leaves should be renewed weekly.
The water for filling the aquarium should have the following parameters - soft and slightly acidic, the dGH and pH values are responsible for this. More details about water parameters and methods of changing them are described in detail in the section "Hydrochemical composition of water".
The minimum set of equipment consists of an aerator, heater, lighting and filtration system. Higher requirements are imposed on the latter. It is advisable to purchase the most efficient filter available to you financially. Fillers based on peat can be used as a filter material; in addition to cleaning, they can acidify water.
Peaceful and somewhat shy fish, it needs quiet, quiet neighbors. Together with the Hilodus, you can keep some South American cichlids, Koridoras catfish and other peaceful representatives of the Amazon. It prefers to stay in a flock of at least 10 individuals, with a smaller number in the presence of other fish, they may suffer from excessive stress.
Breeding / reproduction
A very troublesome process for most aquarists who enjoy watching their pets but are not willing to spend a lot of time and resources for breeding. Before spawning, the largest males and females are deposited in separate reservoirs, where they live for 2-3 weeks and intensively feed on live food. In this case, dry packaged food is not suitable. Then they are combined in a spawning aquarium, which is a container with a low water height of up to 20 cm, soft and acidic. Registration is not required, the only thing is that it is advisable to place a fine mesh on the bottom, which protects the eggs from being eaten. The equipment consists of a simple sponge filter, aerator, a low power lighting system and a heater. The temperature is set 2-3 degrees higher than in the general aquarium.
The parents-to-be are placed in the spawning aquarium in the evening, so that they sit down to acclimatize overnight. Spawning may start the next day or you will have to wait, in which case, do not forget to feed them. After a short courtship procedure, each female lays up to 300 eggs. Without a protective mesh, the eggs will be eaten!
The parents are returned to the common aquarium, and the eggs are placed in a three-liter jar. The height of the water is up to 5 cm, and a weak blowing with an aerator is set, the temperature is maintained around 28 ° C. The fry appear after 4–5 days, grow unevenly, some will significantly outstrip in growth, but cannibalism was not noticed.