Amphibia is a class under the Chordata phylum and Vertebrata subphylum. In this article, we will learn 1. Definition of Amphibians, 2. General characteristics of Amphibians, and 3. Economic importance of Amphibians.
Definition of Amphibians
Amphibia is a class under the Chordata phylum and Vertebrata subphylum. “Amphi” means double and “bios” means life. Amphibians are the animals who pass their life in two mediums. They live in the water as a larva and live on the land as an adult. So, the animals who pass the early / larvae stage of their life in the water and pass the adult stage on land is called amphibian. They are distinguished by having gills for breathing in the water in the larval stage and having lungs in the adult stage for breathing on air. Example: Frogs, Toads, Newts, Salamanders, Caecilians, etc.
General Characteristics of Amphibia
1. They are cold-blooded vertebrate animals.
2. Their embryonic stage is aquatic and the adult stage is terrestrial.
3. The body is divided into head and trunk.
4. Their skin is smooth. Glands are present on the skin which keep the skin moist.
5. Scaleless, if present, are hidden in the skin.
6. Mouth large, tooth present, both upper and lower jaws have small homodont teeth.
7. Skull articulates with the atlas by two occipital condyles.
8. Auditory columellar aperture fitting into fenestra ovalis.
9. Limbs tetrapodus pentactyle type.
10. The heart of the amphibians is divided into two atria and one ventricle. That means the heart is three-chambered.
11. Aortic arches of amphibians are symmetrical.
12. Gills and a well-developed tail are present during the larval stage.
13. They have ten pairs of cranial nerves. Vagus is the last cranial nerve.
14. They have no paired fins.
15. Males do not have the copulatory organs.
16. They are mostly oviparous.
17. Their blood has RBCs (Red Blood Corpuscle). RBCs have nucleus and also contain haemoglobin.
18. Their skin also works as a respiratory organ. That’s why it is necessary to keep the skin moist.
19. External ear is absent in the amphibians, however, some scientists claimed that the tympanum is the external ear.
20. Digestive system and nervous system are well developed.
21. Eggs have a gelatinous covering and the amphibians lay their eggs in the water.
22. Sexes are separate.
23. Fertilization is mostly external.
24. They show sexual dimorphism.
25. Their development is indirect with metamorphosis.
Example: Duttaphrynus melanostictus, Rana tigrina, Frogs, Toads, Newts, Salamanders, etc.
Economic Importance of Amphibians
Almost all the species are important to mankind but the amphibians are very special in this sector. Amphibians have vast economic importance and they are very special to humans. Some of the importance is given below.
Scientific Study
- Frogs, toads, and newts are widely used in laboratories and they are dissected by school and college students to learn.
- They are also used for physiological experiments, human pregnancy tests, pharmacology etc.
As Food
- Frogs and toads are being eaten by many people around the world.
- In the USA, Japan, and some other countries, the fleshy hindlimbs have a great demand as food.
- Besides frogs and toads, other amphibians like salamanders are also eaten by people in many countries.
- The frog cultivating industry is now growing and the farmers export the hindlimbs of the frogs to other countries.
Predation
- Frogs and toads eat noxious insects.
- Garden toads destroy all the harmful insects and save the plants.
- In some countries, gardeners buy toads for their garden to control the harmful insects.
Medicinal Value
- Toads are used in Chinese medicine.
- The skin of toads secret a digitalis-like substance that increases blood pressure when injected into humans.
As Pet
- Frogs and toads are used as pets nowadays. People keep them as a pet inside the aquarium.
- The African Bull Frogs, Pacman frogs, Dart frogs, African Dwarf frogs, Spadefoot toads, and Whites Tree frogs have huge demand in this pet industry.
Poisonous Amphibia
- Amphibians have poison glands on the dorsal surface of their body and produce poison to defend themselves from predators.
- Bufo marinus produces bufotoxins which are fatal to dogs and cats.
- Poison of Dendrobates, a South American frog, is used by the tribal people to poison the point of their arrows.
- Colorful frogs and toads can be poisonous and the poison can be serious to humans also.
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Read More:
- Hoplobatrachus tigerinus (Previously Rana tigrina) | Indian Bull Frog
- General Characters of All Classes of Vertebrates.
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