Research Crayfish in my aquarium
Work completed:
student of class 3-A
State Educational Establishment of the LPR "Artyomovskaya"
secondary school No. 8"
Vyazovskaya Arina
Scientific adviser:
Kulikova Elena Nikolaevna
teacher primary classes
Dad told me that crayfish are bottom cleaners of the reservoirs in which they live. Crayfish feed on the decaying remains of aquatic plants and dead fish. Crayfish are a natural indicator of reservoir pollution. They live only in clean water and are very sensitive to water pollution.
Relevance of the work
Water pollution problem - ecological problem our entire planet. Everything in nature is interconnected: By harming one, we destroy the other! The mass death of crayfish should make everyone think about the critical state of the environmental situation as a whole!
In his research work I want to find out if crayfish can live in home aquarium, promote its purification and respond to the level of water pollution in the aquarium.
Assumption: normal life activity of crayfish is possible in a home aquarium (it will develop and grow a claw); our crustacean will help cleanse the environment in the aquarium and will respond to the level of water pollution.
Target:
- research opportunity vital activity crayfish in home aquarium;
- influence of his life activities on the level of pollution aquarium
Object of study: crayfish living in our aquarium. Subject of study: the life activity of my crayfish. Research methods: observation, experiment, generalization.
Research objectives: 1 . Study theoretical material: - structural features of cancer and its habitat; what crayfish eat and what benefits they bring. 2. To experimentally investigate whether normal life activity of crayfish is possible in a home aquarium; the influence of the life activity of crayfish on the level of pollution in the aquarium. 3. Systematize and summarize the material. 4. Introduce your classmates to the results of the study.
Crayfish is the most striking and widespread representative of the crustacean class, since it can be found in all fresh water bodies, but only in clean water. Crayfish - the same age as many dinosaurs. This crustacean appeared and formed as separate species back in the Jurassic period, which is about 130 million years ago.
Features of the structure of cancer Crayfish - the largest of the crustaceans. Its length reaches 20 cm. The body is covered with a durable brown-green shell and is clearly divided into the front part - a fused cephalothorax and abdomen with a wide fin at the end. There are two pairs of whiskers on the cancer's head. These are the organs of smell and touch. Near the mouth, the crayfish has several pairs of jaw appendages, with which it finely grinds pieces of food and sends them into the small mouth. The eyes are complex in structure, consisting of individual ocelli, mosaically united into one whole. There are a pair of claws on the cancer's chest. The claw muscles are very strong. Crayfish need claws to protect themselves from enemies and to hold food in front of their mouth.
If a limb is suddenly lost, the crayfish grows a new one - immediately after molting. Behind the claws on the cephalothorax of the crayfish there are 4 pairs of walking legs. Small abdominal legs can be seen on the abdomen. The cancer constantly moves them, pushing water to the gills, which are located under the chest shell. Cancer is very sensitive to the purity of water. Therefore, if the water in the aquarium does not change for a long time, the cancer quickly dies.
The growth rate of crayfish depends on the composition of the water and the ambient temperature. aquatic environment, the density of habitat of relatives in the reservoir, the presence of food in it. A cancer measuring 20-25 centimeters may already be twenty years old.
Benefits of crayfish
- Crayfish, by their nature, are kind of cleaners of the bottom of the reservoirs in which they live. Crayfish are indicators of the cleanliness of a reservoir. They are orderlies, since their main food is the decaying remains of aquatic plants, as well as dead fish. By eating such food, crayfish clean water bodies. Even in the cold winter, when crayfish rush to the bottom of the reservoir to burrow into the silt, they continue to eat fish that have died from lack of oxygen.
Features of life Crayfish live in river creeks, small lakes and ponds, but only in clean water. Therefore, experts consider reservoirs containing crayfish to be clean. Crayfish live at depths from half a meter to three. The most suitable places for habitation are captured by large males, leaving less suitable places for weak males and females. Cancers lead a reclusive lifestyle. They spend the whole day in their burrow under a stone or under a snag, with their long whiskers outstretched. In the evening they crawl out of their shelter in search of food. Crayfish feed on small, sedentary
and animals, algae,
often eat dead fish
snails and worms. Durable shell protects
cancer from enemies, but holds back
his height. Therefore, from time to time
time the cancer sheds and sheds
the cover that has become tight.
Having shed its shell, some cancer
time is helpless and can easily
become prey for perch or pike.
But soon a new one appears on it
shell.
My observations 1 day After the crayfish was released into the aquarium, it hid in the farthest corner of its new home. Didn't crawl out of there all day. Day 2 Cancer, as before, hides in the far corner. And when night came, he became very active, we heard him moving pebbles at the bottom of the aquarium. This observation confirms that crayfish are nocturnal Lifestyle. During the day they usually sleep or resting in shelter.
Day 3 During the day, the cancer crawled out of its hiding place, exploring new territory. Quite quickly he began to swim head first. The fish show interest in him and swim around him. I noticed that the number of snails began to decrease. 4 day Cancer behaves restlessly, constantly trying to get out of the aquarium. Climbs higher. Even got stuck in the filter. Probably the water near the filter is cleaner.
5 day We threw a piece of meat into the aquarium. No one expected such a reaction from the cancer: it instantly got out of its hiding place, crawled towards the prey (head first) and began to eat very quickly. He grabs a piece of food with his paws and very quickly begins to eat, fingering with his upper and lower jaws(they look a lot like little paws). Day 6 Cancer has stopped climbing higher, but is studying the bottom. He climbed into the new house that we made especially for him.
Day 7 We read that crayfish are very fond of oak leaves. When we put the leaf in the aquarium, the cancer did not show much interest in it (as food), but periodically crawled up to it and plucked off a piece. Day 8 Cancer has completely settled into his new place. Moves freely around the aquarium and gets along well with fish. Ate several snails.
Day 39
Cancer changed his “clothes” to new ones. Looking into the aquarium in the morning, we noticed that
that the cancer lies motionless. Having looked closely, we found out that it was only a shell, and the cancer itself was sitting nearby in a thicket of grass. (When the cancer grows, it molts - sheds its “tight” chitinous layer). Our cancer has molted, which means it is growing and developing! His new shell is very soft.
Day 45 The new shell hardened. We saw a new small claw. Got it
crayfish from the aquarium to
better consider.
Indeed - my cancer
A new claw is growing!
This confirms that
normal life activity
crayfish
possible at home
aquarium.
Conducting an experiment
We did not turn on the filter in the aquarium for some time. During this time, the water in it became much less polluted than before (before the appearance of cancer). Our crustacean cleans the aquarium of debris and small snails that constantly ate
aquarium plants.
This confirms that crayfish -
cleaners of their habitat .
Conclusion
My assumption that normal life activity of crayfish is possible in a home aquarium was confirmed.
While observing the crayfish in the aquarium, I found out that the crayfish feels great at home and leads an active lifestyle. Goes well with aquarium fish. He is an excellent “sanitary”, cleaning the aquarium from debris and small snails that constantly ate aquarium plants. His restless behavior may indicate
increasing the level of water pollution in the aquarium.
And the change of shell and the growing claw -
confirmation that our crustacean continues
grow and develop normally.
The cover is hard, chitinous, and serves as an exoskeleton. Crayfish breathe through gills. The body consists of a cephalothorax and a flat, segmented abdomen. The cephalothorax consists of two parts: anterior (head) and posterior (thoracic), which are fused together. There is a sharp spike on the front of the head. In the recesses on the sides of the thorn, bulging eyes sit on movable stalks, and two pairs of thin antennae extend from the front: some short, others long. These are the organs of touch and smell. The structure of the eyes is complex, mosaic (consisting of individual ocelli joined together).
On the sides of the mouth there are modified limbs: the front pair are called upper jaws, second and third bottom. The next five pairs of thoracic single-branched limbs, of which the first pair are claws, the remaining four pairs are walking legs. The crayfish uses its claws for defense and attack. The abdomen of the crayfish consists of seven segments and has five pairs of two-branched limbs, which are used for swimming. The sixth pair of abdominal legs, together with the seventh abdominal segment, forms the caudal fin. Males are larger than females, have more powerful claws, and in females the abdominal segments are noticeably wider than the cephalothorax.
When a limb is lost, a new one grows after molting. The stomach consists of two sections: in the first, food is ground with chitinous teeth, and in the second, the crushed food is filtered. Next, the food enters the intestines, and then into the digestive gland, where it is digested and absorbed nutrients. Undigested remains are expelled through the anus, located on the middle blade of the caudal fin. Circulatory system in crayfish it is not closed. Oxygen dissolved in water penetrates through the gills into the blood, and oxygen accumulated in the blood carbon dioxide it is expelled through the gills. Nervous system consists of the peripharyngeal nerve ring and the ventral nerve cord.
Habitat Fresh pure water: rivers, lakes, ponds, fast or flowing streams (3-5 m deep and with depressions up to 7-12 m). In summer, the water should warm up to 16-22C. Crayfish are very sensitive to water pollution, so the places where they are found indicate the ecological cleanliness of these reservoirs.
Nutrition Plant (up to 90%) and meat (molluscs, worms, insects and their larvae, tadpoles) food. In summer, crayfish feed on algae and fresh aquatic plants (pondweed, elodea, nettle, water lily, horsetail), and in winter on fallen leaves. During one meal, the female eats more than the male, but she also eats less often. The crayfish looks for food without moving far from the hole, but if there is not enough food, it can migrate to the sea. It feeds on plant foods, as well as dead and living animals. Active at dusk and at night (during the day, crayfish hide under stones or in burrows dug at the bottom or near the shore under tree roots). Crayfish smell food from a great distance, especially if the corpses of frogs, fish and other animals have begun to decompose.
Behavior Crayfish hunt at night. During the day it hides in shelters (under stones, tree roots, in burrows or any objects lying at the bottom), which it protects from other crayfish. It digs holes, the length of which can reach 35 cm. In summer it lives in shallow water, in winter it moves to depths where the soil is strong, clayey or sandy. There are cases of cannibalism. A crayfish crawls backwards. In case of danger, it stirs up mud with the help of its tail fin and swims away with a sharp movement. IN conflict situations between a male and a female, the male always dominates. If two males meet, the larger one usually wins.
Interesting fact During the times of serfdom, a particularly cruel master could send a serf to catch crayfish in the winter as punishment. This is where the saying “I’ll show you where the crayfish spend the winter” comes from!
Slide 1
Slide 2
The cover is hard, chitinous, and serves as an exoskeleton. Crayfish breathe through gills. The body consists of a cephalothorax and a flat, segmented abdomen. The cephalothorax consists of two parts: anterior (head) and posterior (thoracic), which are fused together. There is a sharp spike on the front of the head. In the recesses on the sides of the thorn, bulging eyes sit on movable stalks, and two pairs of thin antennae extend from the front: some short, others long. These are the organs of touch and smell. The structure of the eyes is complex, mosaic (consisting of individual ocelli joined together).
Slide 3
On the sides of the mouth there are modified limbs: the front pair are called the upper jaws, the second and third are called the lower jaws. The next five pairs of thoracic single-branched limbs, of which the first pair are claws, the remaining four pairs are walking legs. The crayfish uses its claws for defense and attack. The abdomen of the crayfish consists of seven segments and has five pairs of two-branched limbs, which are used for swimming. The sixth pair of abdominal legs, together with the seventh abdominal segment, forms the caudal fin. Males are larger than females, have more powerful claws, and in females the abdominal segments are noticeably wider than the cephalothorax.
Slide 4
When a limb is lost, a new one grows after molting. The stomach consists of two sections: in the first, food is ground with chitinous teeth, and in the second, the crushed food is filtered. Next, the food enters the intestines, and then into the digestive gland, where it is digested and absorbed nutrients. Undigested remains are expelled through the anus, located on the middle blade of the caudal fin. The circulatory system of crayfish is not closed. Oxygen dissolved in water penetrates through the gills into the blood, and carbon dioxide accumulated in the blood is expelled through the gills. The nervous system consists of the peripharyngeal nerve ring and the ventral nerve cord.
Slide 5
Color: varies depending on the properties of the water and habitat. Most often the color is greenish-brown, brownish-greenish or blue-brown. Size: males - up to 20 cm, females - slightly smaller. Life expectancy: 8-10 years.
Slide 6
Habitat Fresh, clean water: rivers, lakes, ponds, fast or flowing streams (3-5 m deep and with depressions up to 7-12 m). In summer, the water should warm up to 16-22’C. Crayfish are very sensitive to water pollution, so the places where they are found indicate the ecological cleanliness of these reservoirs.
Slide 7
Nutrition Plant (up to 90%) and meat (molluscs, worms, insects and their larvae, tadpoles) food. In summer, crayfish feed on algae and fresh aquatic plants (pondweed, elodea, nettle, water lily, horsetail), and in winter on fallen leaves. During one meal, the female eats more than the male, but she also eats less often. The crayfish looks for food without moving far from the hole, but if there is not enough food, it can migrate 100-250 m. It feeds on plant foods, as well as dead and living animals. Active at dusk and at night (during the day, crayfish hide under stones or in burrows dug at the bottom or near the shore under tree roots). Crayfish smell food from a great distance, especially if the corpses of frogs, fish and other animals have begun to decompose.
Slide 8
Behavior Crayfish hunt at night. During the day it hides in shelters (under stones, tree roots, in burrows or any objects lying at the bottom), which it protects from other crayfish. It digs holes, the length of which can reach 35 cm. In summer it lives in shallow water, in winter it moves to depths where the soil is strong, clayey or sandy. There are cases of cannibalism. A crayfish crawls backwards. In case of danger, it stirs up mud with the help of its tail fin and swims away with a sharp movement. In conflict situations between a male and a female, the male always dominates. If two males meet, the larger one usually wins.
Slide 2
The cover is hard, chitinous, and serves as an exoskeleton. Crayfish breathe through gills. The body consists of a cephalothorax and a flat, segmented abdomen. The cephalothorax consists of two parts: anterior (head) and posterior (thoracic), which are fused together. There is a sharp spike on the front of the head. In the recesses on the sides of the thorn, bulging eyes sit on movable stalks, and two pairs of thin antennae extend from the front: some short, others long. These are the organs of touch and smell. The structure of the eyes is complex, mosaic (consisting of individual ocelli joined together).
Slide 3
On the sides of the mouth there are modified limbs: the front pair are called the upper jaws, the second and third are called the lower jaws. The next five pairs of thoracic single-branched limbs, of which the first pair are claws, the remaining four pairs are walking legs. The crayfish uses its claws for defense and attack. The abdomen of the crayfish consists of seven segments and has five pairs of two-branched limbs, which are used for swimming. The sixth pair of abdominal legs, together with the seventh abdominal segment, forms the caudal fin. Males are larger than females, have more powerful claws, and in females the abdominal segments are noticeably wider than the cephalothorax.
Slide 4
When a limb is lost, a new one grows after molting. The stomach consists of two sections: in the first, food is ground with chitinous teeth, and in the second, the crushed food is filtered. Next, the food enters the intestines, and then into the digestive gland, where it is digested and absorbed nutrients. Undigested remains are expelled through the anus, located on the middle blade of the caudal fin. The circulatory system of crayfish is not closed. Oxygen dissolved in water penetrates through the gills into the blood, and carbon dioxide accumulated in the blood is expelled through the gills. The nervous system consists of the peripharyngeal nerve ring and the ventral nerve cord.
Slide 5
Color: varies depending on the properties of the water and habitat. Most often the color is greenish-brown, brownish-greenish or blue-brown. Size: males - up to 20 cm, females - slightly smaller. Life expectancy: 8-10 years.
Slide 6
Habitat Fresh, clean water: rivers, lakes, ponds, fast or flowing streams (3-5 m deep and with depressions up to 7-12 m). In summer, the water should warm up to 16-22’C. Crayfish are very sensitive to water pollution, so the places where they are found indicate the ecological cleanliness of these reservoirs.
Slide 7
Nutrition Plant (up to 90%) and meat (molluscs, worms, insects and their larvae, tadpoles) food. In summer, crayfish feed on algae and fresh aquatic plants (pondweed, elodea, nettle, water lily, horsetail), and in winter on fallen leaves. During one meal, the female eats more than the male, but she also eats less often. The crayfish looks for food without moving far from the hole, but if there is not enough food, it can migrate 100-250 m. It feeds on plant foods, as well as dead and living animals. Active at dusk and at night (during the day, crayfish hide under stones or in burrows dug at the bottom or near the shore under tree roots). Crayfish smell food from a great distance, especially if the corpses of frogs, fish and other animals have begun to decompose.
Slide 8
Behavior Crayfish hunt at night. During the day it hides in shelters (under stones, tree roots, in burrows or any objects lying at the bottom), which it protects from other crayfish. It digs holes, the length of which can reach 35 cm. In summer it lives in shallow water, in winter it moves to depths where the soil is strong, clayey or sandy. There are cases of cannibalism. A crayfish crawls backwards. In case of danger, it stirs up mud with the help of its tail fin and swims away with a sharp movement. In conflict situations between a male and a female, the male always dominates. If two males meet, the larger one usually wins.
