Toad

Toad is a common name for certain frogs, especially of the family Bufonidae. It is characterized by dry and leathery skin, short legs, and large lumps in the parotid gland. Scientific taxonomy does not distinguish between frogs and toads, but it is in popular culture that toads are associated with drier and rougher skin and more terrestrial habitats. Usually, the largest bump on the skin of a toad is the bump that covers its parotid gland. The bumps are often called warts, but they have nothing to do with pathological warts. They are not caused by an infection. Toads move from non-breeding areas to breeding ponds and lakes. Toads, like many amphibians, exhibit hatchery fidelity. Individual American toads return to the pond where they were born to breed, and they may find siblings as potential mates. Although examples of inbreeding may exist in one species, siblings rarely mate. Toad animal recognizes and avoids mating with close relatives. The advertising sound made by men seems to be a signal for women to recognize relatives. Therefore, recognition of kinship can avoid inbreeding and the subsequent decline of inbreeding. We will learn more about what is a toad and its different characteristics. 

Toads Amphibians 

Amphibians are animals that live both on land and water and are four-legged vertebrates. All existing amphibians belong to the Lissamphibia group. They inhabit a variety of habitats, and most species live in terrestrial, fossil, arboreal, or freshwater ecosystems. Therefore, amphibians usually start with aquatic larvae, but some species have developed behavioral adaptations to avoid this. Larvae usually change from gill-bearing larvae to lung-breathing adults. Amphibians and toads amphibians use the skin as a secondary breathing organ. Some small salamanders and land frogs have no lungs and rely entirely on skin. They are similar to lizards on the surface, but like mammals and birds, reptiles are amniotic and do not need water bodies to reproduce. Because of their complex reproductive requirements and permeable skin, amphibians are usually ecological indicators. In recent decades, the amphibian populations of many species in the world have declined sharply. The earliest amphibians evolved during the Devonian period are from the sarcopterygian fish with bonilimbed lungs and fins. These characteristics helped to adapt to the continent. They got diversified and became dominant during the Carboniferous and Permian periods, but were later replaced by reptiles and other vertebrates. Over time, the size of amphibians became smaller and their diversity declined, leaving only the modern subclass Lissamphibia. 

The three orders of modern amphibians are Anura that has frogs and toad animal, Urodela, and Apoda. There are approximately 8,000 known species of amphibians, of which nearly 90% are frogs. The smallest amphibian and vertebrate in the world is the New Guinea frog, which measures only 7.7 millimeters in length. The largest surviving amphibian is the 1.8 meters southern China giant salamander. The study of amphibians is called batology, and the study of reptiles and amphibians is called herpetology. 

Skeletal System 

The skeletal system of amphibians and toad animals is structurally homologous with other quadrupeds but has some changes. Except for the legless salamanders and some shortened limbs or limbless salamanders, all animals have limbs. The bones are hollow and very light. The musculoskeletal system is strong and can support the head and body. The bones are completely ossified, and the vertebrae are interwoven with each other through an overlapping process. The chest belt is supported by muscles, and the well-developed pelvic belt is connected to the spine through a pair of sacrums. The iliac bone is tilted forward and the body is closer to the ground than mammals. In most amphibians, the front legs have four toes and the hind legs have five toes, but neither has claws. Some salamanders have fewer toes, while amphibians resemble eels with small and thick legs. Kathia amphibian has no limbs. They dig holes in the manner of earthworms, with muscle contractions all over the body. On the ground or in the water, they move by swinging their bodies left and right. In toads, the hind legs are larger than the front legs, especially in species that move mainly by jumping or swimming. Among walkers and runners, the hind limbs are not that big, while the digger has short limbs and a wide body. The feet are adapted to the lifestyle, with webbing between the toes for swimming, wide, sticky pads for climbing, and keratinized nodules on the hind legs for digging. In most salamanders, the limbs are short, approximately the same length, and extend at right angles from the body. Movement on land is by walking, and the tail is often swayed from side to side or used for support, especially when climbing. In its normal gait, only one leg at a time advances in the same way as its ancestor, the finfish. Some salamanders and certain plethodontids of the genus Aneides climb trees and have long limbs, big toes, and curly tails. In aquatic salamanders and frog tadpoles, the tail has dorsal and pelvic fins, which move from left to right as a means of propulsion. Adult frogs do not have a tail, caecilians only have very short tails. Salamanders use their tails to defend themselves, and some newts plan to abandon them to save lives in a process called auto cutting. Some Plethodontidae species have a weak area at the bottom of the tail, which makes it easy to use this strategy. The tail often continues to swing after separation, which can distract the attacker and allow the newt to escape. Both the tail and limbs can regenerate. Adult frogs cannot regenerate limbs, but tadpoles can.

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Circulatory System 

Here, we will learn about what is a toad circulatory system made up of. Amphibians have juvenile and adult stages, and their circulatory systems are different. In the juvenile or tadpole stage, the circulation is similar to that of fish. A two-chambered heart pumps blood through the gills, where it is oxygenated, then spreads through the body and returns to the heart in a cycle. In adulthood, the toads and the frogs lose their gills and develop into lungs.  

Nervous System 

Here, we will learn about what is a toad nervous system made up of. The nervous system of toads is basically the same as that of other vertebrates, with a central brain, spinal cord, and nerves throughout the body. Amphibian brains are not as developed as those of reptiles, birds, and mammals, but they are similar in form and function to fish. Amphibians are believed to be able to sense pain. The brain is made up of equal parts, the cerebrum, the midbrain, and the cerebellum. Sensory information such as the sense of smell in the olfactory lobe and the vision in the optic lobe is processed by various parts of the brain, and it is also the center of behavior and learning. The cerebellum is the coordination center of muscles, and the medulla oblongata controls some organ functions, including heartbeat and breathing. The brain sends signals through the spinal cord and nerves to regulate the activities of other parts of the body. It is well known that the pineal gland can regulate human sleep patterns, and it is believed that it produces hormones related to hibernation and sleep in amphibians. Tadpoles retain the lateral line system of their ancestor fish, but this is lost in adult land amphibians. Some caecilians have electroreceptors that allow them to locate surrounding objects when they are immersed in water. The toad’s ears are well developed. There is no external ear, but the large, round eardrum is located on the surface of the head behind the eyes. This vibration and sound are transmitted to the inner ear through a bone. In this way, only high-frequency sounds, such as mating calls, can be heard, but low-frequency noise can be detected by another mechanism. There is a special hair cell in the inner ear, called the amphibian papilla, that can detect deeper sounds. Another unique feature of toads and salamanders is the small columnar operculum complex adjacent to the auditory capsule, which is involved in the transmission of air and seismic signals. Salamander ears are not as developed as toads because they generally do not communicate with each other through sound. Tadpole eyes do not have lids, but at metamorphosis, the cornea becomes more domed, the lens becomes flatter, and the lids and related glands and ducts develop. The adult eye is an improvement on the invertebrate eye and the first step in the evolution of the higher vertebrate eye. They allow color vision and depth of focus. There are green rods in the retina, which can receive various wavelengths of light 

System of Digestion and Excretion 

Many toads and other amphibians catch their prey by sticking out a thin tongue with a sticky tip and putting it back in their mouth and then grabbing it with their hands. Some people use inertial feeding to help them swallow their prey, repeatedly pushing the head forward violently, causing the food to move backwards inertially in the mouth. Most amphibians swallow their prey without chewing much, so they have huge stomachs. The short esophagus is lined with cilia to help move food to the stomach, and the mucus produced by the glands in the mouth and pharynx makes it easier for food to pass through. Chitinase produced in the stomach helps digest the chitin cuticle of arthropod prey. Amphibians have the pancreas, liver, and gallbladder. The liver is usually large, with two lobes. Its size depends on its function as a storage unit of glycogen and fat, and as these storages are accumulated or consumed, they will change with the seasons. Adipose tissue is another important energy storage method, which occurs in the abdomen, under the skin, and in the tails of some newts. There are two kidneys on the dorsal side, near the top of the body cavity. Its job is to filter blood from metabolic waste products and transport urine through the ureter to the bladder, where it is stored before regularly passing through the cloacal catheter. Larvae and most aquatic amphibians excrete nitrogen in the form of ammonia in a large quantity of dilute urine, while terrestrial species need to save water and excrete urea, a less toxic product. Some tree frogs with limited water sources excrete most of their metabolites

Frog 

A frog is any member of a diverse and predominantly carnivorous group of short-body anuras that make up the order Anura which means that they have no tail. The oldest "frog" fossil appeared in the early Triassic in Madagascar, but the age of the frog from the molecular clock shows that its origin can be traced back to the Permian era that is 265 million years ago. Frogs are widely distributed, from tropical to sub-arctic regions, but the highest species diversity is found in tropical rain forests. There are approximately 7,300 species registered, accounting for approximately 88% of the existing amphibian species. They are also one of the five most diverse orders of vertebrates. Warty frog species are often called toads, but the difference between frogs and toads is informal, not one of taxonomy or evolutionary history. Adult frogs are strong, with protruding eyes, protruding tongues, bent limbs down, and no tails. Frogs have glandular skin, and the secretions vary from unsightly to poisonous. Their body has a variety of colors, from well-disguised mottled brown, gray, and green to bright red or vivid patterns of yellow and black to show toxicity and resist predators. Adult frogs live in fresh water and on land. Some species are suitable for living underground or on trees. Frogs often lay eggs in water. The eggs hatch into aquatic larvae called tadpoles with internal tails and gills. They have highly specialized mouth scrapers suitable for herbivorous, omnivorous, or planktonic diets. When they metamorphose into adults, the life cycle is complete. Some species lay eggs on land or bypass the tadpole stage. Adult frogs usually feed on small invertebrates, but omnivorous species also exist, and some feed on plants. Frogskin is rich in microbiota, which is very important for its health. They are an important food source for predators and part of the dynamics of the food web of many ecosystems around the world. The skin is semi-permeable, which makes them prone to dehydration, so they live in humid places or have special adaptability to cope with dry habitats. Frogs make a variety of sounds, especially during their breeding season, and they exhibit many different types of complex behaviors to attract mates, resist predators, and survive in general. Frogs are regarded as food by humans, and they also have many cultural roles in literature, symbolism, and religion. They are also regarded as environmental indicators, and the decline in the number of frogs is often seen as an early warning signal of environmental damage. The number of frogs has declined significantly since the 1950s. More than one-third of species are considered to be in danger of extinction, and more than 120 species are believed to have become extinct since the 1980s. The number of deformities in frogs is on the rise, and a new fungal disease, chytridiomycosis, has spread all over the world. Conservation biologists are working hard to understand the causes of these problems and solve them.