Amphibians Overview and Classification

Questions and Answers

What does the word 'amphibia' mean?

Double life - aquatic and terrestrial

Where do the most primitive tetrapods come from?

Class Amphibia

Describe the skin of members of Class Amphibia.

Skin lacks scales, feathers, or hair; has numerous glands (mucous, poison)

What are amphibians thought to have evolved from?

Sarcopterygian fish Signup and view all the answers

Briefly describe the reproduction method, larvae, and adult form of Class Amphibia.

Most lay eggs in water. Larvae usually aquatic; undergo metamorphosis into adult form. Adults usually semi-terrestrial (tied to water). Signup and view all the answers

What are the 3 orders of Class Amphibia?

Order Caudata - salamanders, Order Gymnophiona - caecilians, Order Anura - frogs Signup and view all the answers

What are 2 general characteristics of Order Caudata (salamanders, sirens, & amphiumas)?

Possess long tail throughout life & has 4 unspecialized legs Signup and view all the answers

What are the variable life history strategies of Order Caudata?

Most terrestrial salamanders live on the forest floor, have aquatic young. Some lay eggs on land, larvae are terrestrial. Some spend most of their lives in water. Some live in caves. Signup and view all the answers

What are 4 characteristics of Newts (Order Caudata)?

Newts often have 3 life forms, aquatic larvae, terrestrial 'eft' stage, and are aquatic as adults. Signup and view all the answers

Describe the general anatomy and reproductive forms of Caecilians (Order Gymnophiona).

Elongated, limbless. Specialized for burrowing. Appear segmented because of folded skin. Larval stages often developed within female, young resemble small adults. Signup and view all the answers

Describe the general anatomy of frogs and toads (Order Anura).

Adults lack tails, caudal vertebra fused. Long, muscular hind limbs with webbed feet. Signup and view all the answers

Describe the reproduction of Order Anura.

External fertilization via amplexus > herbivorous tadpoles > rapid, drastic metamorphosis into adults. Signup and view all the answers

Describe the locomotion of Class Amphibia.

Frogs hop/jump. Salamanders walk with undulating gaits. Caecilians move like an accordion. Signup and view all the answers

What kind of circulatory system & heart does Class Amphibia have?

Closed circulatory system with 3-chambered heart Signup and view all the answers

Generally, Class Amphibia excretes in water and on land.

Ammonia; urea Signup and view all the answers

Some amphibians have a ___ to store urea, and void wastes via _ or ___.

Urinary bladder; skin; cloaca Signup and view all the answers

Class Amphibia cannot survive in _____ environments.

Marine Signup and view all the answers

Aquatic amphibians have a (nervous) system like fish.

Lateral line Signup and view all the answers

Members of Class Amphibia have eyes that are protected and cleaned by a transparent _ _.

Lower eyelid Signup and view all the answers

Members of Class Amphibia are ____, meaning their bodies assume the temperature of the water.

Ectothermic Signup and view all the answers

Almost all adult amphibians are:

Predatory carnivores Signup and view all the answers

Larval frogs are mostly:

Herbivores Signup and view all the answers

Salamanders and caecilians are mostly _____ as larvae.

Predatory carnivores Signup and view all the answers

Frogs have (to make sounds) and (to hear sounds).

Vocal sacs; tympana Signup and view all the answers

Early members of Class Reptilia were the first to possess _____.

Amniotic eggs Signup and view all the answers

Order Testudines (turtles) have a bony shell. The dorsal portion is called the ___ and the ventral portion is called the _.

Carapace; plastron Signup and view all the answers

Order Sphenodontida (tuataras) are primitive, superficially lizard-like, and distinguished by _____.

Tooth characteristics Signup and view all the answers

What is one distinction between lizards and snakes, involving their hearing?

Lizards have ear openings; snakes do not Signup and view all the answers

Order _____ may be the nearest relative to birds.

Crocodylia Signup and view all the answers

Worm Lizards (Order Squamata, Suborder Amphisbaenia) are specialized _____ in tropics or sub-tropics.

Burrowers Signup and view all the answers

Study Notes

Amphibia Overview

"Amphibia" translates to "double life," indicating their aquatic and terrestrial existence.
The most primitive tetrapods are classified under Class Amphibia.
Amphibians' skin is distinct from others, lacking scales, feathers, or hair, and is enriched with mucous and poison glands.

Evolution and Reproduction

Amphibians are believed to have evolved from sarcopterygian fish.
Reproduction typically involves laying eggs in water, with larvae being aquatic and undergoing metamorphosis into semi-terrestrial adults.

Classification and Orders

Class Amphibia is divided into three orders:
- Order Caudata (salamanders)
- Order Gymnophiona (caecilians)
- Order Anura (frogs)

Order Caudata Characteristics

Salamanders possess long tails throughout their lives and four unspecialized legs.
They exhibit variable life histories:
- Terrestrial species often have aquatic young.
- Some lay eggs on land with terrestrial larvae.
- Others spend most of their lives in water or inhabit caves.
Newts display three life forms: aquatic larvae, terrestrial "eft" stage, and adult aquatic forms.

Order Gymnophiona (Caecilians)

Caecilians are elongated and limbless, adapted for burrowing.
Their appearance may seem segmented due to folded skin, and they may exhibit internal development, with larvae resembling small adults.

Order Anura (Frogs and Toads)

Adults in this order lack tails, and the caudal vertebrae are fused.
These amphibians have long, muscular hind limbs with webbed feet.
Reproduction involves external fertilization through amplexus, leading to herbivorous tadpoles and rapid metamorphosis into adults.

Locomotion and Circulatory System

Frogs are known for hopping and jumping, while salamanders walk using undulating gaits, and caecilians move in a coordinated accordion-like manner.
Class Amphibia has a closed circulatory system with a three-chambered heart.

Excretion and Temperature Regulation

Amphibians excrete ammonia in water and urea on land, with some possessing a urinary bladder for urea storage and waste excretion via skin or cloaca.
They cannot survive in marine environments due to their physiological adaptations.
Aquatic amphibians have a lateral line system for sensing vibrations, similar to fish.

Sensory Adaptations

Eyes of amphibians are protected and cleaned by a transparent lower eyelid, an adaptation for their habitat.
Amphibians are ectothermic, regulating their body temperature according to environmental conditions.

Diet and Feeding Habits

Almost all adult amphibians are predatory carnivores, while larval frogs are primarily herbivores.
Salamanders and caecilians also adopt carnivorous diets during their larval stages.

Sound Production and Hearing

Frogs utilize vocal sacs for sound production and tympana for hearing.

Class Reptilia and Evolution

Early reptiles, classified under Class Reptilia, were the first to possess amniotic eggs, a critical evolutionary feature.
Order Testudines (turtles) are characterized by a bony shell, with the dorsal part named carapace and the ventral part named plastron.
Order Sphenodontida (tuataras) is noted for unique tooth features and a lizard-like appearance.
Lizards possess ear openings for hearing, unlike snakes which lack this feature.
Order Crocodylia is considered closely related to birds within reptilian classifications.
Worm lizards, found in the tropics or sub-tropics, have a specialized morphology featuring a single upper tooth distinct from other vertebrates.

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Description

Explore the fascinating world of amphibians, known for their dual life both in water and on land. This quiz covers their evolution, reproduction methods, and the characteristics of their distinct orders: Caudata, Gymnophiona, and Anura. Test your knowledge on these unique creatures and their habitats!