[Biology Class Notes] on Herpetology Pdf for EXAM

In the process of evolution, it was very necessary for the organisms to evolve. We also evolved from the vertebrates. Herpetology is the study of reptiles. We also come around with a question: what is a herpetologist? A herpetologist meaning is a person who studies reptiles. The reptiles were an important part of the evolution along with the amphibians. From our study of amphibians, we got to know that they were the first organisms to come out of the water and started developing lungs. From the amphibians evolved the reptiles which have the presence of scales and very huge diversity. The study of reptiles helps us to understand their nature and characteristic features that are very important for their survival. When we know about reptiles then only we can learn about them and how they are useful for the environment. Here, in this article, we will perform a short study of amphibians and reptiles. 

Amphibians

They are cold-blooded animals. Cold-blooded animals are also known as poikilotherms. The meaning of amphibians is that they are amphibious in nature, this means that they can live both on land and in water. Mostly, they are found in warm countries. They have both smooth and rough types of skin. Also, there are cutaneous glands that are present on their body and it helps them to keep them moist. No presence of scales is there on the body of amphibians. For locomotion, they have two pairs of limbs. They have the presence of gills in their larval stage. Sometimes they are also present in some adults along with lungs. Lungs, buccopharyngeal cavity, skin, and gills are the organs through which these amphibians respire. They have a dicondylic skull. This means that two occipital condyles are present for articulation with the vertebral column. They have a three-chambered heart. Two auricles and one ventricle are present in their heart. Sinus venous and truncus arteriosus are also present in their heart. The hepatic portal vein and the renal portal vein are well developed in their heart. Mesonephric types of kidneys are present in them. In frogs, the urinary bladder is also present. The larva of amphibians is ammonotelic and the adults such as the frogs and toads are ureotelic. The internal and middle ear is present in them. The tympanum helps in covering the middle ear. There is a single ossicle that is the ear ossicle which is present in the middle ear and its name is Columella Auris. In the amphibians, there are a total of 10 pairs of cranial nerves. For breeding purposes, they have to return to the water. The copulatory organs are absent in males. The process of metamorphosis can be seen in them 

Frog

They generally live in water. They are diurnal animals which means that they come out when there is light. The frogs lay their eggs in masses. They have moist skin. Their skin is also smooth and slimy in nature. They have a triangular body and their body is longer in size. Parotid glands are absent in the body of frogs. Webs that are present on their body are well developed. With the help of these webs, they can easily walk and climb on trees. Teeth are present in their upper jaw and their tongue is bifid in nature. External ears are absent in frogs. The tympanum is seen in frogs externally. Their tympanum is present on both sides of their head. 

Toad

The toads are present in the dark and shady corners of the gardens. At the time of breeding, they visit the water. The toads are nocturnal in nature. It means that they come out at night time. They lay their eggs in a line. They have dry, rough, and warty skin. They have a semi-circular head. Their body is shorter in size and they have two parotid glands in their mouth. The webs are rudimentary in nature. In both of their jaws, teeth are absent. They have the presence of an entire tongue. 

Reptiles

As we read above, the study of reptiles is known as herpetology.  A Herpetologist meaning is that a person who studies reptiles vigorously. As their name suggests that these animals have a crawling or creeping mode of locomotion.  These reptiles were the first true land vertebrates. Their skin is dry and cornified in nature. Some epidermal scales and scutes are also present on their body. No external ear opening is present in their body. The ear is represented by the tympanum. Two pairs of limbs are present on their body. They have a three-chambered heart but in crocodiles a four-chambered heart is present. Pleurodont types of teeth are present in lizards and crocodiles. Conical types of teeth are present in their body. The mouth is present at the terminal position of their body. In turtles, teeth are absent. Instead of teeth, the turtle has horny beaks. They are cold-blooded in nature. Uricotelic type of excretion is present in them. In snakes and crocodiles, the urinary bladder is absent. There are 12 pairs of cranial pairs of nerves present. A separate type of sexes is present. Direct type of development is present in them. Their eggs are covered by shells. They are oviparous in nature. The snakes shed their skin. We understood the herpetologist meaning and now we will understand about one such reptile that is a snake. 

Snakes

The study of snakes is known as Serpentology. Serpentology is also known as ophiology. No movable eyelids or external ear openings are present in snakes. They are limbless organisms. Their scaly epidermis of the skin is periodically shed. This process of shedding of skin is known as molting or ecdysis. Their cornified skin cells are shed. All the snakes are oviparous in nature except that of Vipera russelli and Hydrophis. Their parotid glands or superior labial glands are modified to form poisonous glands. The snakes secrete two types of poison that are neurotoxic and hemotoxic. The cobras, sea snakes, and kraits secrete the neurotoxins. The neurotoxin poison works by paralyzing the respiratory muscles and this, in turn, causes asphyxiation. The vipers release the hemotoxins. The hemotoxins cause the tissues and cells to damage and this, in turn, leads to hemorrhage. In the venom of the viper, proteolysin is present. The circulatory system is affected by the venom of the viper. Antivenin and antivenom serum are the drugs that can be used to treat the poison of snakes. They are naturally made antibodies which are extracted from the body of other animals such as horses and then stored for future purposes. To counteract the effect of hemotoxins, Benadryl and antisera drugs are used. The rattlesnakes are named so because of their skeleton which is the quickest moving skeleton in the whole world. They can shake their rattle around 90 times in a second. Due to this, their muscles can tire very easily but they are designed in such a way that they can efficiently use their ATP for the movement of their rattle and warn the predators of any danger.