Arachnids Arachnids class terrestrial arthropods. They unite about thousands of species of spiders, salpugs (phalanxes), scorpions, mites, etc. The science of arachnology deals with the study of arachnids.
External structure arachnids Just like crustaceans, the body of arachnids consists of two sections: 1. Cephalothorax. 2. Abdomen. 3. On the upper side of the cephalothorax in front there are organs of vision - 8 simple eyes. 4.Limbs. 8 walking legs extend from the cephalothorax from below, and 5 are visible in front of them mouthparts: the first pair is the jaws, the second pair is the legs. The tentacles have sensitive hairs that are part of the organs of touch.
The internal structure of arachnids is similar to that of most arthropods. In the body cavity of arachnids there are internal organs, combining into systems: 1. Digestive 2. Excretory 3. Respiratory 4. Circulatory 5. Nervous 6. Reproductive 7. In addition, spiders have a specific arachnoid gland. Internal structure of arachnids
Weaving a web Spiders are distinguished from most arthropods by one important feature - they produce a web thread from a silk-like substance. It is distinguished by so-called spider warts. This thread is used for many purposes, but its most important purpose is to use it for hunting.
Spider Hunting While waiting for prey, the spider is usually located near the net in a hidden nest made of cobwebs. A signal thread is stretched from the center of the network to it. When prey gets into the net and begins to struggle in it, the signal thread oscillates. At this sign, the spider rushes from its shelter to its prey and thickly entangles it in its web. It injects poison into the prey. Then the spider leaves the prey for a while and takes refuge in a shelter.
Spider nutrition The contents of the poisonous glands not only kill the victim, but also act on it as digestive juice. After about an hour, the spider returns and sucks up the already partially digested liquid contents of the prey, of which only the chitinous cover remains. The spider cannot eat solid food. Thus, in spiders, preliminary digestion of food occurs outside the body.
Poisonous spiders All spiders kill prey with poison, but only 30 species pose a threat to humans. The most dangerous are representatives of the genus Latrodectus (especially the black widow and karakurt), living in many warm countries, Australian funnel-web spiders and one Bolivian jumping spider.
Spider breathing In the front part of the abdomen lies a pair of pulmonary sacs communicating with environment. The walls of the bags form numerous leaf folds, inside which blood circulates. It is enriched with oxygen from the air located between the folds. In addition to the lung sacs, the spider has two bundles of respiratory tubes in its abdomen - tracheae, which open outward through a common respiratory opening.
Biology lesson on the topic "Arachnids class". 7th grade
Biology teacher: Kriulina I.V.
Goals:
Educational: To acquaint students with the diversity and lifestyle of arachnids, the structural features and vital functions that allowed them to become one of the first settlers of land, their significance in nature and human life.
Developmental: Contribute to the continued development of skills in working with tests for further preparation for the State Examination and the OGE, working with reference signals
Educational: Teach careful attitude to nature, showing that each organism has its place in the ecosystem, its significance in nature and human life, its unique history and originality.
Equipment: Table “Crustaceans”, “Arachnids”, reference signals, cards, tests on sheets
During the classes
I. Test of knowledge
– Where does cancer live, what are the features of adaptation to its environment in its external structure, behavior, reproduction.
– What are the features of the internal structure?
– Digestive system. (The intestines of crustaceans usually have a chewing stomach and a “liver” that opens into the midgut.) Why and how can crustacean stomachs chew?
– Why do you come across crayfish with one claw smaller than the other? (The crayfish’s claw can come off during a fight with an enemy or during an unsuccessful moult. Then it grows back (regenerates), but turns out to be smaller in size).
– Respiratory, circulatory system. Why can crayfish taken out of water remain alive for several days? (Thanks to the lateral edges of the shell, which protect the gills from drying out. As long as the gills of the crayfish are kept moist, the crayfish do not die).
– Excretory, nervous systems.
- Reproduction.
– What is the importance of crustaceans in nature and human life?
Biological dictation (All students answer in a notebook, followed by verification)
1.Crayfish breathes through gills (Yes).
2.Cancer is diurnal (No).
3.The body of cancer consists of two sections (Yes).
4. Cancer has simple eyes (No).
5.Crayfish are herbivores (No).
6. Cancer always moves backwards (No).
7. Cancer is characterized by regeneration of claws (Yes).
8.With the help of walking legs, the crayfish moves along the bottom (Yes).
9.Circulatory system cancer is not closed (Yes).
10. The mobility of the cancer’s eyes compensates for the immobility of its head (Yes).
11.Crayfish are the “orderlies” of water bodies (Yes).
12. Cancer uses its jaws to grab food and send it into the mouth (Yes).
13. The abdomen of cancer consists of 10 segments (No).
14. Claws are organs of defense, attack, and food capture (Yes).
15. Cancer’s blood is red (No).
16. Female crayfish lay eggs in winter (Yes).
17.Crayfish live up to 50 years (No).
II. Learning new material
– Let’s once again list 3 classes from the type of Arthropods that we study: Crustaceans; Arachnids; Insects.
What are the names of Arachnids? Latin? (Arachnida).
– Who knows why?
- The famous naturalist D'Orbigny once sported trousers made from the web of Brazilian spiders. He wore them for a long time, but they did not wear out. And Louis XIV, King of France, the parliament of the city of Montpellier once presented stockings and gloves woven from silky threads as a gift French spiders.
“It is well established that spider webs stop bleeding. Just take it fresh and clean.
– What is the spider itself, the owner of the web?
– The goal of our lesson: to find out not only the structure of spiders using the example of a cross, but also to talk about what arthropods are included in the class Arachnids, what role they play in nature and human life. Topic entry: “Class Arachnids.”
The Arachnida class includes up to 62,000 species.
These are haymakers, ticks, spiders, scorpions, etc. All of them are terrestrial animals, except for the silverback spider. Many people weave webs.
– What is common to all arthropods? (Limbs, chitinous cover). The body consists of 2 sections - the cephalothorax and abdomen. The abdomen is separated from the cephalothorax by a constriction. They do not have antennae or compound eyes. There are 4 pairs of legs on the cephalothorax.
Also several pairs of simple eyes; and below the jaw are chelicerae. The spider uses them to grab the victim. There is a channel with poison inside. There are short, hairy tentacles, or pedipalps (organs of touch).
Below on the abdomen are arachnoid warts that produce cobwebs. These are modified abdominal legs. (What does this mean?) - About ancestors who had legs for movement. On his hind legs there are comb-shaped claws that help pull out the arachnoid threads from the glands and collect them into one.
The thread consists of protein. From the arachnoid warts of one spider, up to 4 km of web can be pulled out. They need the web to catch prey, to make cocoons, to protect eggs from adverse influences. Therefore, it can be of several varieties: dry, wet, sticky, corrugated. It serves for different purposes. The web is thinner and stronger than the threads of a silkworm caterpillar.
But industrial production such threads cannot be established, because spiders are very voracious and you can’t get enough flies, and the climate is not suitable everywhere.
The spider weaves a trapping net from cobweb threads. First a frame with rays converging towards the center, then a long, thin and very sticky thread, placing it in the center of the spiral. (The mass of a web, equal in length to the equator of the globe, is 340 g.)
Then, waiting for prey, he sits near the net in a hidden nest made of cobwebs. A signal thread is stretched from the center of the network to it.
– Observations of the spider’s behavior show that it jumps out of its hiding place and quickly moves towards the fly only if there is a medium-sized fly there: if a small fly hits, the spider does not pay attention to it. How does a spider know the size of its prey?
The circulatory system is like that of crayfish. Which?
- Unclosed. Hemolymph. The heart has the shape of a tube or double rhombus
Respiratory system. The spider is breathing atmospheric air. It has a pair of pulmonary sacs, entwined with blood vessels, and bundles of trachea, tubes that permeate the body of the animal.
Working with a textbook drawing (p. 123)
Excretory system. The tubules are Malpighian vessels. At one end they collect metabolic products, and at the other they flow into the intestines. Water is absorbed in the intestines. Therefore, spiders save water and can do without it (a vicious circle of water consumption).
Nervous system. Like crayfish, only the thoracic nodes and the suprapharyngeal node are developed.
Reproduction system. Dioecious animals. Fertilization in the female’s body. The female lays eggs openly or entwines them with a web (cocoon).
– There are 62,000 species of arachnids in nature.
We will get to know some of the representatives, as they live in our area and are very dangerous.
– Karakurt (its poison is 15 times stronger than that of a rattlesnake).
- Tarantula.
– Scorpio (found in Central Asia, in the Caucasus, in Crimea).
– Tarantula (its digestive juice dissolves 3 g of mouse tissue per day, weighing 20 g).
- Haymaker.
– Serebryanka (
– In addition to Spiders, Arachnids also include ticks (messages
– How are ticks and spiders similar?
- What is the difference?
– Which mite reduces the yield of fruit and melon crops?
A – taiga, B – scabies, C – dog, D – spider.
– Which ticks are harmful to human health?
A – soil, B – scabies, C – canine, D – arachnoid.
Did you know that in ancient times kings and Popes, and great scientists: Herodotus, Philip II and Pope Clement VII died from scabies.
– Are arachnids necessary in nature?
– Without spiders, people could die from various diseases, since they are carried by flies, and as scientists calculated, armed with a microscope, there are 26,000,000 microbes on the body of one fly.
– They are food for birds.
– Some harm plants, animals and humans.
– They are carriers of diseases.
– Participate in soil formation.
– And once spiders helped the French defeat Holland.
So, general signs arachnids:
Mainly terrestrial species;
4 pairs of walking legs;
Predators => adapt, venom glands, spider warts;
Body length from 0.1 mm to 12 cm.
III. Consolidation of knowledge
Given syllables: PA SE NO KA RA SKOR UK KO SETS KURT PION
Make up the names of arachnids from them.
(spider, haymaker, karakurt, scorpion)
IV. Homework.
Subject: biology
Teacher: Talitskikh Marina Vladimirovna
Educational institution: MBOU - secondary school in the village of Veseloye, Mozdok district
Topic: "Arachnids"
Basic provisions on the topic:
1. - Class Arachnida.
- Representatives of arachnids are eight-legged land arthropods in which the body is divided into a cephalothorax and abdomen, connected by a thin constriction or fused.
- Arachnids do not have antennae.
- On the cephalothorax there are six pairs of limbs - chelicerae, tentacles and four pairs of walking legs. There are no legs on the abdomen. Their respiratory organs are the lungs and trachea.
- Arachnids have simple eyes. Arachnids are dioecious animals.
- The body length of various representatives of this class is from 0.1 mm to 17 cm. They are widespread throughout the globe. Most of them are terrestrial animals. Among ticks and spiders there are secondary aquatic forms.
- The arachnid class includes up to 60 thousand species.
2. External structure and lifestyle of spiders- rice. 91 page 120
- Cross spiders(so named for the cross-shaped pattern on the dorsal side of the body) can be found in the forest, garden, park, and on the window frames of suburban and village houses. Most of the time, the spider sits in the center of its trapping network of adhesive thread - cobweb.
- The spider's body consists of two sections: the cephalothorax and the spherical abdomen. The abdomen is separated from the cephalothorax by a narrow constriction. At the anterior end of the cephalothorax there are four pairs of eyes, and below there are hook-shaped hard jaws - chelicerae. With them the spider grabs its prey. There is a canal inside the chelicerae. Through it, poison from the poisonous glands located at the base of the chelicerae enters the victim’s body. Next to the chelicerae there are short organs of touch covered with sensitive hairs - the tentacles. Four pairs of walking legs are located on the sides of the cephalothorax.
- The body is covered with a light, durable and fairly elastic chitinous cuticle. Like crayfish, spiders periodically molt, shedding their chitinous cover. At this time they grow.
- At the lower end of the abdomen there are three pairs of arachnoid warts that produce cobwebs - these are modified abdominal legs.
- In a spider, like in crustaceans, the body cavity is of a mixed nature - during development it arises from the connection of the primary and secondary body cavities.
3. Digestive system
- The cross spider cannot feed on solid food. Having caught prey, for example some insect, with the help of a web, it kills it with poison and releases digestive juices into its body. After some time, the contents of the captured insect liquefy and the spider sucks it out. All that remains of the victim is a chitinous shell. This method of digestion is called extraintestinal.
- The spider's digestive system consists of the mouth, pharynx, esophagus, stomach, and intestines. In the midgut, long blind processes increase its volume and absorption surface. Undigested residues are expelled through the anus.
4. Respiratory system.
- The spider's respiratory organs are the lungs and trachea. The lungs or pulmonary sacs are located at the bottom of the abdomen, in the front part. These lungs developed from the gills of the distant ancestors of spiders that lived in water. The cross spider has two pairs of non-branching trachea - long tubes with special spiral chitinous thickenings inside. They are located in the back of the abdomen.
5. Circulatory system
- in spiders it is not closed.
Heart looks like a long tube located on the dorsal side of the abdomen. They leave the heart blood vessels. Like crustaceans, spiders have hemolymph circulating in their bodies.
6. Excretory system
- represented by two long tubes - Malpighian vessels.
- One end of the Malpighian vessels ends blindly in the body of the spider, the other opens into the hind intestine. Metabolic products are removed through the walls of the Malpighian vessels, which are then excreted. Water is absorbed in the intestines. That. Spiders save water, so they can live in dry places.
7. Nervous system
- the spider consists of the cephalothoracic ganglion and numerous nerves extending from it.
8. Reproduction.
- Fertilization in spiders is internal. The male transfers sperm to genital opening females with the help of special outgrowths located on the front legs. After some time, the female lays eggs and braids them with a web. This is how a cocoon is formed.
- Small spiders develop from the eggs. In the fall, they release cobwebs, and on them, like parachutes, they are carried by the wind to long distances- resettlement occurs.
9. Variety of arachnids
Ë Spiders
Ë Haymakers
Ë Scorpios
Ë Pliers
Slide 2
External structure of the spider
Spider warts
Slide 3
Internal structure of a spider
Slide 4
Slide 5
Spider weaving a web.
Spiders can move very quickly.
Little spiders travel through the air
They hold on to cobweb threads and are carried by the wind.
Spiders themselves secrete a substance from which the web is formed.
All spiders are capable of this.
Slide 6
tunnel spider
U different types Spiders have different shapes of webs.
Slide 7
Monarch butterfly caught in a web.
The web is sticky. All the insects that got into it
find themselves caught.
Slide 8
Why is a web needed?
The web is a means
Movement
Breeding and protection of offspring
Slide 9
Garden spider and dragonfly
Then the spider comes, injects poison and eats the victim.
Slide 10
Common spiderlings crawl out of the cocoon
REPRODUCTION
Spider with cocoon
Slide 11
Class Arachnids (orders)
Slide 12
Spider Squad
Tarantula karakurt (black widow)
Slide 13
Cross spider
Wolf spider
Spider crab
Slide 14
Detachment of haymakers
Slide 15
Scorpion squad
Slide 16
Squad Ticks
Slide 17
Ixodid tick bite causes illness spinal cord in humans
Slide 18
If a person is bitten by a tick who has not received the vaccine against tick-borne encephalitis, you must apply for medical care
Slide 19
Little harm, big benefit.
Spiders that have settled in houses litter the walls of our homes with cobwebs.
Few spiders are poisonous; They are, of course, dangerous to people who live where there are a lot of poisonous spiders.
But the benefits are invaluable!
Slide 20
A spider is a friend to man!
They feed on insects, often harmful ones. By destroying them, spiders bring benefits to humans.
Spiders catch in the net
five hundred insects per day.
Flies predominate in this catch.
Slide 21
After all, a fly is only seemingly harmless. There are 20 million microbes on the body of just one fly! And such terrible ones, from which people get tuberculosis, anthrax, cholera, typhoid fever, dysentery, various worms... Humanity would all perish. Only the enemies of flies, mainly spiders, save us from such a nightmare.
