Amphibians Facts & Worksheets

Amphibians are tiny vertebrates that require moisture to survive, such as water. Frogs, toads, salamanders, and newts are among the species that make up this category. Through their very thin skin, all are able to breathe and absorb water.

See the fact file below for more information on Amphibians, or you can download our 30-page Amphibians worksheet pack to utilize within the classroom or home environment.

Key Facts & Information

WHAT IS AN AMPHIBIAN?

• Frogs, toads, salamanders, newts, and caecilians—worm-like creatures with underdeveloped eyes—are all members of the group of cold-blooded vertebrates known as amphibians.
• They are born with gills, some of which they lose as they age and others of which they retain throughout their entire lives.
• The name “amphibian” refers to animals that spend some of their life in the water and some on land. Greek term “amphibian” means “double life” in English.
• Additionally, amphibians have unique skin glands that create functional proteins. Some move gasses like carbon dioxide, oxygen, and water into or out of the animal. Others combat infections caused by bacteria or fungi. 

EVOLUTIONARY HISTORY

• According to fossil evidence, amphibians descended from lobe-finned lungfish about 365 million years ago. They were very successful since they were the first terrestrial vertebrates. 
• It is also said that the first amphibians originated from sarcopterygian fish in the Devonian period, which had lungs and bone fins that helped them adapt to dry land.
• During the Carboniferous and Permian periods, they evolved and rose to dominance, but subsequently, reptiles and other vertebrates supplanted them. 
• While studies continue, scientists theorize that the ancestry of current frogs is members of the Lissamphibia order, which first appeared during the Early Triassic, some 250 million years ago.

COMMON CHARACTERISTICS

Anatomy

• All amphibians have reproductive, digestive, and excretory systems. The cloaca, a bodily cavity, is shared by all three systems. 
• Gametes enter the cloaca from the reproductive system, while wastes enter it from the digestive and excretory systems. The wastes and gametes might leave the body through an aperture in the cloaca.
• Amphibians have a three-chambered heart and a somewhat complicated circulatory system.
• Their intricate neurological system enables them to communicate with one another and their surroundings.
• Amphibians can taste and smell substances thanks to their sensory organs, which include their eyes and ears. 
• Frogs often have the best hearing and vision among all amphibians. To produce sounds, frogs also have a voice box or larynx.
• Amphibians are the first true tetrapods or four-legged animals. They often have wet skin and no scales. The skin, scales, feathers, hair, and nails of tetrapod animals, such as amphibians and humans, include keratin, a tough, fibrous protein. Different keratin kinds have varying levels of durability.

LIFE CYCLE

• Amphibians undergo a biological process known as metamorphosis after birth or hatching that results in an obvious and abrupt change in the animal’s body structure as a result of cell development and differentiation.
• Amphibians often lay their spawn or jelly-covered eggs in quiet freshwater, frequently next to water plants. The offspring, known as tadpoles, are aquatic and have feathery, external gills at first, but eventually develop lungs and legs and leave the water.
• At first, they resemble legless blobs with tails. Only in the spring do adult amphibians return to the water to reproduce; they spend most of their lives on land, typically in wet settings.
  • A Frog’s Life – The newborn frog grows front legs, and its tail gradually shrinks until it disappears. 
  • The nutrients that are taken in as food is within the tail. Then, the young frog is ready to leap from the pond and begin living on land. 
  • When a frog reaches adulthood, it switches from feeding on plants to feeding on insects. To produce a mature frog, an adult frog must wait four years. When a frog reaches sexual maturity, it starts to lay eggs, which allows the frog’s life cycle to restart.
• On the other hand, the development of salamanders is highly diverse. Others, like the axolotl, exhibit paedomorphosis and never become terrestrial adults, whilst certain species go through a significant reorganization when transitioning from aquatic larvae to terrestrial adults.

REPRODUCTION

• In amphibians, sexual reproduction is the primary method of reproduction. It involves the mingling of sperm produced by male testes with eggs produced by female ovaries.
• Although some amphibians also lay their eggs on land, most need water to procreate. These land-dwelling invertebrates have evolved a number of adaptations to keep their eggs wet. 
• Even in brackish water, some amphibians may survive. However, there is currently no evidence that any amphibian can successfully lay eggs in saltwater environments.

THREE ORDERS OF AMPHIBIANS

Anura (frogs)

• Frogs and toads are also known as anurans. Most amphibians, including frogs and toads, have short torsos, no tails as adults, and lengthy hind legs that move in a hop-like manner. The calls of many anurans can be used to distinguish between different species.
• Tadpoles, the offspring of biphasic frogs and toads, have very different morphologies from their adult terrestrial counterparts. The absence of a tail in adult frogs and toads is one characteristic that sets them apart from other amphibians.
• In comparison to other amphibians, frogs and toads also have substantially longer hind legs, which have adapted for jumping. Frogs have a leaping capacity of up to 20 times their own length.

Caudata (salamanders)

• The Caudata is a group that includes all living salamanders and any extinct amphibian species that are more closely related to salamanders than to frogs.
• They often resemble lizards from the outside, with tiny bodies, blunt snouts, small limbs that stick out at an angle to the body, and a tail in both the larval and adult phases.
• Salamanders and newts retain their tails as adults, unlike frogs and toads. These amphibians also have somewhat uniformly sized legs and a large body with small legs. 
• This is due to the fact that they are more suited to swimming and walking than jumping. Salamanders have the peculiar capacity to regenerate or grow new legs after they have been amputated by predators.

Gymnophiona (caecilians)

• A class of limbless, vermiform, or serpentine amphibians is known as the caecilians. They are the least well-known order of amphibians since they spend most of their time living in the ground and on the surfaces of streams. Despite having no arms or legs, they are skilled diggers who use their powerful head and body muscles to push through mud and soil.
• Caecilians frequently have very tiny eyes, which are assumed to be only capable of distinguishing between light and dark. 
• Some species have eyes that are wholly encased in skin as a survival strategy for an existence that is virtually entirely underground. The caecilians have two tiny, chemically sensitive tentacles on their faces that can detect food and possibly aid navigation.

Amphibians Worksheets

This fantastic bundle includes everything you need to know about Amphibians across 30 in-depth pages. These ready-to-use worksheets are perfect for teaching kids about Amphibians, a class of cold-blooded vertebrates characterized by their ability to live both on land and in water, often undergoing metamorphosis from a juvenile water-dwelling form to a terrestrial adult form.

Complete List of Included Worksheets

Below is a list of all the worksheets included in this document.

• Amphibians Facts
• Prehistoric Word Find
• Characteristics
• Life Cycle
• Amphibians are Unique
• Colorful Amphibians
• They are Rare!
• Saving the Giant
• The Quack Toad
• Amphibious Mythology
• Animals I know

Frequently Asked Questions

What are the defining characteristics of amphibians?

Amphibians are characterized by their moist, permeable skin, their biphasic life cycle (spending part of their life in water and part on land), and their ability to undergo metamorphosis. They are cold-blooded and have a three-chambered heart.

What is the difference between a frog and a toad?

The distinction between frogs and toads is primarily a matter of appearance and habitat, not biology. Frogs are typically more streamlined and have smooth, moist skin, while toads are more heavily built, with dry, warty skin. Frogs live near bodies of water, while toads are more likely to live in dry, terrestrial habitats.

What is the purpose of metamorphosis in amphibians?

Metamorphosis serves a number of purposes for amphibians, including allowing them to adapt to different habitats and food sources and avoid predators. In many species, the aquatic larval stage is a time of rapid growth when the amphibian can take advantage of abundant food sources. In contrast, the terrestrial adult stage allows them to avoid predators and reproduce.

Are all amphibians nocturnal?

No, not all amphibians are nocturnal. Some species are active during the day, while others are active at night, depending on the species and its habitat.

Are amphibians an endangered species?

Yes, many species of amphibians are considered endangered or at risk of extinction due to habitat loss, climate change, and spreading diseases such as chytridiomycosis. Conservation efforts are underway to protect and conserve amphibian populations, but it is challenging given the unique life cycle and habitat requirements of these animals.

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