Insects together with arachnids belong to the oldest animals in the entire world. They are over 400 million years old from the evolutionary point of view. Insects can be found almost everywhere and often in huge numbers. On one hand they may annoy human beings but on the other hand they are very helpful in many ways for instance in removing dead animals, producing honey, etc. Anatomy: An insect body is made of three main parts: a head, a thorax and an abdomen. The thorax/chest consists of three segments. There are three pairs of extremities on the ventral side and two pairs of wings on the dorsal side. The belly has got twelve segments and has no extremities. These animals have got complex eyes. The Insect Class can be divided into two groups. On one hand there is insect which contain wings (Pterygota, majority) and on the other hand there is insect without any wings (Apterygota, such as: Collembola or Lepisma Saccharina). Insacta Class can be divided into two other groups: Firstly, there is Hemimetabolia, which is the insect with an incomplete metamorphosis. The insect in this group undergoes several stages of life: a fertilised egg, a nymph and an imago (adult). The nymph and the imago usually live in the same water environment. Secondly, there is Holometabolia, insect with the complete metamorphosis. This insect undergoes following stages of life: a fertilised egg, a larva, a nympha and an adult animal. Larvae often inhabit different environment as adult insects do. This group includes butterflies, bugs, bees, hornets, flies etc… Although insects can be sometimes dangerous and annoying to human beings in fact we cannot imagine our lives without it. Let’s face to sit down on the grass in the land and do not see any ants or hear any bees or spot any incredibly beautiful butterflies – it is even hard to imagine. The exact number of fishes cannot be specified. There are approximately 22 000 different species and scientists are still sorting them out. Anatomy: Fishes are superbly designed for the water life while water covers about 71 % of the earth’s surface. Their skin is mucous and it is made of scales whose design and shape vary a lot. The majority of fishes have got a skeleton made of bones. The spine is made of vertebrae. Ribs are made from the lateral vertebrae prominences. These ribs stabilize the ventral side and protect inner organs as well. There are tiny bones being created in the paired fins area (breast and ventral fins). From the evolutionary point of view, these small bones are a base for future extremities. Apart from that, the breast fins are a base for future shoulder-blade and the ventral fins are a base for future pelvic area. It is obvious that neither the shoulder-blade area nor the pelvic area are fixed to the spine. Both of them are fixed only to muscles and ligaments. Physiology: The fishes spend their life in the water. They breathe with gills which contain a number of tiny blood vessels and capillaries. These are well protected. Heart of a fish has got two parts: an atrium and a ventricle. The blood from the ventricle flows to an artery which divides into the small ones. These small arteries bring blood to the gills where the blood is oxygenated. Then it flows to the spine artery which divides and subsequently brings blood containing inevitable oxygen to particular organs. Deoxygenated blood from all organs is then collected from all veins to the main one. Last but not least the main vein brings deoxygenated blood to the atrium. This is how blood simply circulates in the fish’s body. Few fishes have got primitive lungs. Digestion is simple as well. Fish’s mouth may contain a huge variety of teeth which kill a prey and crush it. Then it follows to the pharynx and esophagus (oesophagus). Distal/Aboral oesophagus part is wider and it is followed by a stomach (gaster, ventriculus). Intestine (intestinum) is not very differentiated. In the ventral esophagus area there is a sack filled with gas. The gas pressure can be changed. The brain consists of five parts. The most peculiar thing about fish is definitely the “side-line”. It is located on the lateral side of the fish’s body. It contains a number of sensory and very sensitive nerves. These nerves enable fish to orientate themselves when it is dark and in murky water. Other sensory organs include eyes, smell organ etc. We can divide fishes into several categories. In the first category there are fishes which live in the fresh water (for instance Lepidosiren). They are able to breathe either with gills or with lung sacks as well. The second category contains extinct fishes. Latimera chalumnae is probably the only surviving fish at this time. The third category is a huge one. It contains fishes which inhabits seas and oceans but freshwater as well. Their fins are made of ray-shaped bones. In Europe we can find for example: Cyprinus carpio (Carp), Tinca tinca, Chondrostoma nasus, Leuciscus cephalus, Salmo (Salmon), Essox (Pike), Barbus barbus, Perca fluviatilis and so on. The size of the fishes varies a lot. For instance The Whale shark measures up to 19 m whereas the Luzon Goby only 11 mm. Eating habits are different as well. Some fish feed on meat (a number of sharks, piranhas) whereas other ones feed on plankton, insects etc. (carps). Some fish inhabit sea (rays) and on the other hand there are only freshwater fish such as trout. Apart from that for instance salmons inhabit both types of the water throughout their lives. To put it in a nut shell fishes represent a huge variety of animals which total number still remains unknown and moreover it exceeds the number of mammals, birds, amphibians and reptiles together. Reptiles finalize the transfer from the water to the land. Their body is protected by a dry skin. There are over 6 100 described species so far. Reptiles are a lot different compared to amphibians. Even the egg structure is a lot different. Reptiles’ egg has got three protective membranes plus a shell. This enables them to survive without any water. Anatomy: The skeleton is almost entirely made of bones. In this group we can spot the differentiation in the cervical spine. There is an atlas and an axis (the first two cervical vertebrae), which allow these animals to move their head more freely compared to amphibians. Apart from that we can spot another change in the thorax part. Ribs are fixed to the vertebrae. Physiology: Breathing is also on higher level compared to amphibians. The inner lung surface is more developed and differentiated. Heart consists of two atriums and one ventricle. The heart’s ventricle is separated by an incomplete septum into two different parts. The right one is used for the venous blood and on the other hand the left part of the ventricle is used for the arterial blood. The pulmonal artery comes from the right part of the heart’s ventricle and aorta comes from the left part. As there is an incomplete ventricular septum there comes to a mixture of an oxygenized and deoxygenized blood. Reptiles just like amphibians belong to ectothermal animals, so their body temperature depends on their environment. Reproduction: Reptiles lay eggs into the water. Around their embryo there is an “amnion” being created. The space between embryo and the amnion is filled with amniotic fluid. Nervous system especially hemispheres in the frontal lobe are more developed compared to amphibians. There are several groups in the Reptilia class. Chelonia (Turtles): can live in the freshwater as well as in the sea. Besides they can live terrestrial life as well. They have got a unique and a typical shelter which is mainly used for their protection.In Europe we can find Emys orbicularis, Testudo gracea and so on. Another group is called Squamata. Their body is covered with scales (squama means a scale). Squamata include the majority of reptile species. This category can be divided into two subcategories: Lizards (Sauria) and Snakes (Ophidia). Lizards have got extremities and they can move their eye-lids. This subcategory includes species such as Lacerta agilis, Anguis fragilis etc. Snakes do not have any extremities. They do not have any pelvic area or a chest bone. Their skeleton consists of two parts: a thorax part and a tail one. Some species have sharp teeth which may contain a poison. In central Europe we can find Vipera berus ar Natrix Natrix. Crocodiles ( Loricata): are the most developed reptiles. Their heart has got two atriums and two ventricles. Moreover these two ventricles are separated by a complete septum! Teeth are located in alveolae in a jaw (specially designed teeth holes). They even use a diaphragm for breathing. This group includes Alligator, Cajman, Gavialis and crocodiles (for instance Crocodilus niloticus which can be long up to 10 metres). Reptiles Class is a heterogeneous group of vertebrates which colonize every type of land or water. They can be found in all areas ranging from the oceans to the deserts and from mountain to Arctic. Mammals are the most developed class in the animal kingdom. They are over 200 million yeas old and lived even at the age of the dinosaurs. As their name reveals they feed their young with mammary glands. They give birth to live young and have hair compared to feathers or scales which other animal classes have. Anatomy: From the anatomical point of view, their skeleton is in many ways similar to the human body. Their body is covered with a fur. They have got a bony skeleton. The spine can be divided into cervical, thoracic, lumbar, sacral and a tail part. The cervical consists of 7 parts / vertebrae (just like the humans), thoracic of 12-18 vertebrae and lumbar of 2-8 vertebrae. Sacral vertebrae are together fixed in the sacral bone. The number of vertebrae in the tail part may vary a lot. The first two vertebrae (atlas and axis) enable mammals to move their head to the sides (left / right) as well as up and down. Ribs are fixed to the thoracic vertebrae. They are also used as a great protection. Physiology: Lungs consist of many small alveoli - this rapidly increases their inner surface. Diaphragm is between the thorax and the abdominal part. It also participates in breathing and is an inevitable inhaling muscle. The heart is made of four completely separated parts. There are two atriums and two ventricles. Deoxygenated blood flows through the right heart whereas the oxygenated blood flows through the left heart. So there are two separated blood circulations. The blood circulation starts in the right atrium and then the blood flows into the right ventricle. From the right ventricle the blood flows into the lungs where it is oxygenated. Consequently it flows into the left atrium and then into the left ventricle. From the left ventricle the oxygenated blood flows into the entire body to all organs. There it gives inevitable oxygen to tissues and last but not least the deoxygenated blood comes through veins into the right atrium. And in the right atrium it starts all over again. Mammals have got a constant body temperature, they are endothermic. They also do have sweat glands which enable them to cool themselves. The alimentary canal starts with a mouth with teeth. Teeth have got different shape and different functions too. A food comes through the pharynx and esophagus into the stomach (gaster). Chemical digestion starts in stomach and is finished in duodenum, jejunum and ileum. Pancreas and gall bladder participate in digestion. Gall helps to digest fat and pancreatic enzymes proteins and sugars. Intestunum tenue (duodenum, jejunum and ileum) participates (apart from digestion) in resorption too. The concentration of indigestible food takes place in colon. Only water is digested there. The alimentary canal ends as an anus. Mammals have got pair of kidneys, which excrete toxic and abundant fluid. They are placed in the lumbar area on the both sides. Nervous system is extraordinary developed. The frontal part has got the most impact over other brain parts. Sensory organs are well developed as well. Reproduction: There is always an internal fertilisation. Development of a new young takes place in the female’s organ called uterus. During the intrauterine development the small young is/are connected to the mother’s body with placenta. The placenta fulfils plenty of functions. Firstly it enables breathing, then nutrition and last but not least it excretes toxic substances. Intrauterine period is finished by giving birth. After the birth, a small offspring breaths an atmospheric air with its lungs and starts to suck mother’s milk (=mammals). Systematically we can divide Mammalia Class into two Suclasses: Prototheria (Monotremes) and Theria Subclass. Consequently Theria Subclass is divided into two other Infraclasses: Metatheria/Marsupialia Infraclass (Marsiupial mammals) and Eutheria/Placentalia Infraclass (Placenal mammals). Prototheria (Monotremes) are primitive mammals. They live in Australia and nearby islands. They still have got some features reminding of birds. Jaws are prolonged. Alimentary tract, secretory and sex organs have the same end called cloaca. They lay eggs and small ones suck mother’s milk, however nipples are not developed. This Subclass includes animals such as Ornithorhynchus and Echidna (Spiny anteater). Metatheria/Marsupialia Infraclass (Marsiupial mammals) includes animals for instance Macropus (kangaroo), Didelphis, Notoryctes, Petaurus, Phascolaretos (koala). Females have got 2 uteruses and a special sack (marsupium) on the abdomen. There is an underdeveloped placenta in the uterus and cannot enable the full foetus development. Therefore Marsupial mammals give birth to immature small young. Their development continues and is finished in a unique marsupial pouch outside the mother’s belly which also contains nipples. Placentalia Infaclass include a huge number of animals. They are spread all around the world. They create a placenta, which enables foetus a complete intrauterine development. This infraclass can be also divided into several subcategories. Insectivora have teeth which are underdeveloped. Their brain is very small and hemispheres are smooth and do no contain any gyruses. Their food mainly consists of insects. This group includes Erinaceus (hedgehog) and a Mole (Talpa). Chiroptera (Bats) are mammals which are able to fly! Their body structure is ideal for flying (strong clavicles, long fingers etc.). Their sense of hearing is developed exceptionally well. They move by using echolocation. On the other hand their sight is very poor. Edentata: these animals live in South America. Their teeth are very weak. Rodentia: their jaws are very strong and include sharp teeth. They breed several times per year and have plenty of small young. These young mature rather early. This group includes a mouse (Mus), a rat (Ratus) etc. Carnivora have very strong jaws with knife-sharp teeth. This group includes animals such as a cat (Felis), a lion (Felis), a jaguar (Panthera), a tiger (Felis), a dog (Canis), a fox (Vulpes), a bear (Ursus), hyena (Hyena) etc. Pinnipedia is another group. These animals live in water (for instance: a seal (Phoca). Whales (Cetacea) also live in water. They have got a huge amount of fat located under the skin. It is a great isolation layer. This group can be divided into two subgroups: whales with teeth (e.g.: Balaena) and whales without any teeth (e.g.: a dolphin (Delphinus)). Horses (Equus), rhinos (Rhinoceros) belong to Perissodactyla group. Artiodactyla have only four fingers. The first finger (thumb) is not developed. Almost the entire weight of the animal is on the third and the fourth finger. Some animals from this group have got only a simple stomach (Hippopotamus (Hippopotamus)) whereas other animals have got a stomach made of four parts (e.g.: a bison (Bison), a deer (Cervus), a camel (Camelus) etc.). Elephants belong to Proboscidae. Primates (Primates) have got five fingers on each extremity. The thumb can oppose other fingers which enable to grab things. Some primates have nails others claws. Lemurs (Lemur), Monkeys (Simiae) have got nails. Their brain is well developed then hemispheres are big and contain gyruses. Some animals have a wide nose septum (Hapalidae) whereas others a thin one (Catarrhina). Others have only a subtle nose (e.g.: Gorillas (Gorilla), Orang-utans (Pongo)). The vast majority of these vertebrates move by flying. Birds have a unique cover – feathers. These consist of a special substance called keratin which gives birds extraordinary skills. Birds are extremely old animals. First birds lived 140 million years ago! These days there are approximately 8 600 different birds’ types which live and fly all around the world. Anatomy: Their skeleton is completely bony and aerodynamically suitable for flying. Long bones are tubular and therefore extremely light. The skull is fixed to the backbone only with one vertebra just like in the Reptilia Class. A beak is created by prolonging the upper and the lower jaw. A neck is quite long and very movable. A chest bone is wide with a number of muscles, especially those responsible for flying, are fixed to it. Even the bone in the wings is attached to the chest bone. The birds’ body is covered with feathers. It is extremely light and on the other hand it is also a thermal isolation. Feather lies in two layers. Physiology: The birds breathe with lungs however these cannot be extended. The lung capacity is extended by five pairs of air sacks which store the air. These sacks are located next to some inner organs and tubular bones. Some birds have got even a vocal organ. The heart is divided into two atriums and two ventricles. Deoxygenated blood flows through the right heart whereas the oxygenated blood flows through the left heart. So there are two separated blood circulations. The blood circulation starts in the right atrium and then the blood flows into the right ventricle. From the right ventricle the blood flows into the lungs where it is oxygenated. Subsequently it flows into the left atrium and then into the left ventricle. From the left ventricle the oxygenated blood flows into the entire body to all organs. There it gives inevitable oxygen to tissues and last but not least the deoxygenated blood comes through veins into the right atrium. In the right atrium it starts all over again. Birds belong to endothermic animals, so their body temperature is stable and is not influenced by the environment. The average body temperature is about 42 Celsius degrees. In the brain we can observe a huge development especially in the frontal part. Birds use their instinct very much, besides they take care of their offspring. Their orientation skills are remarkable too. Life span: All birds lay eggs. There are three main layers in the egg. Amnion is filled with amniotic fluid (reptiles have got amnion as well), then chorion and alantois. Alantois is used as a respiratory and a secretory organ. The female birds have got only one ovary. There are often differences in sexes. This is called sexual dimorphism. The Bird Class can be divided into two infraclasses: Saururae and Ornithurae. Infraclass Saururae includes already extinct birds. They had been a link between reptiles and birds. They were able to climb trees but unable to fly. Their jaws were pretty sharp. The second Infraclass includes few extinct birds and also a number of birds which can be seen all around the world. This infraclass can be divided into several categories such as: Ratitae, Natantes and Volantes. Ratitae: These bords cannot fly. Their wings are not developed enough. They can walk and run therefore their extremities are very strong. Nantes: cannot fly as well. They live mostly in water in the Antarctica. They use their extremities mainly for swimming (for instance: penguins (Phenisciformes)). Volantes: They are the biggest category of all living birds these days. They can fly. This group can be also divided into several subcategories such as: Columbiformes (e.g.: pigeons (Columba)), Anseriformes (swans (Cyngus)), Ralliformes, Pelecaniformes (pelicans (Pelecasnus)), Ciconiiformes, Cuculiformes, Falconiformes (eagle (Aquilla)), Strigiformes (Owels (Stix)), Coraciaformes, Piciformes and Passeriformes (sparrow (Passer)). Bird Class includes a number of animals which differ in size, food habits, locomotion, vocalization, colour etc. Some birds take care of their small young others do not. All in all birds hale always been a great fascination for humans.
