Questions and Answers
How did amphibians adapt to living on land?
- Amphibians replaced gills with another respiratory organ, the lungs. 2. Skin that prevents loss of water. 3. Eyelids that allow them to adapt to vision outside of the water. 4. An eardrum developed to separate the external ear from the middle ear. 5. A tail that disappears in adulthood (in frogs and toads).
What are the three Orders of Class Amphibia?
- Urodela, containing salamanders and newts. 2. Anura, containing frogs and toads. 3. Apoda, containing caecilians.
What are tetrapods?
Vertebrates with four limbs.
What is keratin?
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What are mucous glands?
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What is a three-chambered heart?
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What is a tadpole?
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How do amphibians reproduce?
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What features distinguish frogs and toads from other amphibians?
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What are the characteristics of salamanders and newts?
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What are the characteristics of caecilians?
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What are the tetrapod characteristics?
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What is double circulation?
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What is Acanthostega?
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What is Ichthyostega?
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What was the Carboniferous period?
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What was the Devonian period?
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What are the characteristics of Class Amphibia?
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What is Order Gymnophiona?
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What is Order Urodela?
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What is direct development?
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Study Notes
Amphibian Adaptations
- Amphibians developed lungs to replace gills for breathing air.
- Skin adapted to reduce water loss, aiding survival on land.
- Eyelids evolved for better vision in terrestrial environments.
- Eardrums formed to separate external and middle ear, enhancing hearing capabilities.
- Adult amphibians, like frogs and toads, lose their tails.
Classification of Amphibians
- Class Amphibia consists of three Orders:
- Urodela (salamanders and newts)
- Anura (frogs and toads)
- Apoda (caecilians)
Key Terminology
- Tetrapods: Vertebrates with four limbs, including amphibians.
- Keratin: A fibrous protein found in skin and other structures; amphibian skin has low keratin content allowing gas and water permeability.
- Mucous Glands: Produce slippery mucus through glycoprotein secretion, aiding in hydration and locomotion.
Cardiovascular Features
- Amphibians possess a three-chambered heart with two atria and one ventricle, a characteristic shared with reptiles (excluding crocodilians).
- Double Circulation: System features pulmonary and systemic circuits with blood passing through the heart after each circuit.
Life Cycle and Reproduction
- Amphibians reproduce sexually via external or internal fertilization.
- Mating behaviors may include vocalizations or scent marking.
- Eggs are laid in water, ensuring larvae development and metamorphosis into adults.
Distinguishing Features of Frogs and Toads
- Adults lack tails and possess elongated hind legs adapted for jumping.
- Frogs can leap significantly, up to 20 times their body length.
- Frogs typically inhabit more aquatic environments than toads, which prefer terrestrial habitats.
- Frogs have smoother and moister skin compared to the drier texture of toads.
Characteristics of Salamanders and Newts
- Retain tails into adulthood; possess a long body and short limbs.
- Adapted for both walking and swimming; limbs are equal in length.
- Notable for regenerative abilities, capable of regrowing lost limbs.
Unique Features of Caecilians
- Legless, elongated, worm-like body structure.
- Evolved from a tetrapod ancestor, adapted for burrowing.
- Possess small jaws and eyes, thriving in damp environments.
Evolutionary Context
- Acanthostega: An early tetrapod characterized by its four legs and digits, not strong enough for land walking.
- Ichthyostega: One of the earliest amphibian-like tetrapods known from fossil records.
- Carboniferous Period: Lasted from 354 to 290 million years ago; featured abundant coal deposits, extensive forest swamps, and large plant species.
- Devonian Period: Marked by the diversification of terrestrial species and the emergence of amphibians, known as the "Age of Fishes."
Class Amphibia Overview
- Amphibians are defined by a bony skeleton, moist glandular skin, two pairs of limbs, and a three-chambered heart.
- Species commonly include frogs and toads, displaying adaptability for life both in water and on land.
Order Features
- Order Gymnophiona (Caecilians): Include legless, worm-shaped creatures with moist skin and some bony scales; predominantly found in tropical regions.
- Order Urodela (Salamanders): Have four similarly sized limbs, which aid in their waddling gait and are significant insect predators, contributing to ecosystem balance.
Developmental Concepts
- Direct Development: A reproductive strategy where young develop directly into the adult form without a larval stage.
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Description
Test your knowledge on the unique characteristics and classification of amphibians. This quiz covers their adaptations for life on land and the three main orders of amphibians. Challenge yourself and learn more about these fascinating creatures.