If youโve ever watched birds along the coast, youโve probably noticed they behave a little differently from backyard birds. Sea and shore birds are full of fascinating adaptations that help them survive in windy, salty, ever-changing environments. Here are some amazing (and sometimes weird!) things to look for next time youโre near the water:
Before we dive in: If youโre an educator planning to teach sea and shorebirds, great learning resources are key to deepening understanding! I think you and your students will love my complete Sea and Shorebirds Unit (plus youโll support my blog with your purchase! โค๏ธ)
Many seabirds, like terns, donโt build elaborate nests in trees. Instead, they create a simple โscrapeโโa shallow depression in sand or gravel. It might not look like much, but it helps keep eggs from rolling away and provides just enough shelter to blend into their surroundings.
Albatrosses have some of the largest wingspans of any bird on Earthโsome stretching to about 10 feet! These wings allow them to glide effortlessly on ocean winds, sometimes traveling miles without flapping much at all.
3. Skimmers Fish in a Totally Unique Way
Skimmers have one of the strangest feeding strategies in the bird world. They fly low over the water with their lower bill slicing through the surface. When they bump into a fish, SNAP!โthey quickly grab it. Their uneven bill (longer on the bottom than the top) makes this possible.
4. Cormorants Have to Dry Their Wings
Unlike ducks, cormorants donโt have fully waterproof feathers. After diving for fish, their feathers get soaked. Thatโs why youโll often see them perched with wings spread wideโair-drying in the sun and wind before their next dive.
5. Some Birds Can Drink Saltwater
Living by the ocean presents a salty challengeโbut many seabirds have a special solution. Birds like gulls have salt glands near their eyes that remove excess salt from their bodies. The salt is then expelled through their nostrilsโkind of like sneezing out seawater!
6. Shorebirds Are Long-Distance Migrants
Many shorebirds are incredible travelers. Some species migrate thousands of miles each year between breeding and feeding grounds. For example, the Arctic tern migrates between the Arctic and Antarctic!
Take a close look at different shorebirds, and youโll notice a wide variety of beak shapes. Thatโs because each one is adapted for a specific feeding style. Some probe deep into the sand for worms, while others pick tiny creatures off the surface. These specialized tools help reduce competition and allow many species to share the same habitat.
Sea and shore birds may live in harsh environments, but their unique adaptations make them perfectly suited for life along the water. Next time youโre at the beach or coastal wetland, take a moment to watch themโyou might just spot one of these amazing behaviors in action!
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Vertebrates are a category of animals that share one important trait – they have a backbone. There are seven different groups, or classes, of vertebrates on Earth. These include amphibians, birds, mammals, reptiles, and three kinds of fish. In this post, we’ll explore these groups and find out what makes each one unique.
Before we dive in: If youโre an educator planning to teach vertebrates, great learning resources are key to deepening understanding! I think you and your students will love my 5 units on vertebrate classes, which you can also find within my complete Vertebrates Bundle (plus youโll support my blog with your purchase! โค๏ธ)
Fish are a large and diverse group of vertebrates. Technically, they’re actually three groups of vertebrates. The three main types of fish are jawless fish, cartilaginous fish, and bony fish. Many animals that we might not always think of as fish belong to these groups. For example, sharks, skates, and rays are all types of cartilaginous fish. The bony fish group includes fish that follow the classic body plan, like salmon, tuna, and sturgeons. But this group also includes some unique fish whose bodies look quite different from their relatives – like eels and seahorses.
Fish live almost everywhere there is waterโfrom icy mountain streams to warm coral reefs and from shallow wetlands to the deepest parts of the ocean. They range in size from tiny guppies to giant sharks and manta rays. Some fish, like tuna, are streamlined for fast swimming across the open ocean. Others, like pufferfish or seahorses, have unusual body shapes and move slowly among reefs and seaweed.
Their diets and lifestyles vary, too. Some fish, like sharks and tuna, are predators that hunt other animals. Others filter feed tiny plankton from the water or graze on aquatic plants and coral. Some fish, like salmon, migrate long distances between freshwater and the ocean, while others spend their entire lives in one small pond. Regardless of size, shape, or habitat, fish show an incredible range of adaptations that allow them to survive in aquatic habitats all around the globe!
Fish Traits
Spine
Typically cold-blooded (some exceptions)
Gills
Fins
Lateral line (sensory organ)
Found in water
Examples of Fish
Trout
Tuna
Seahorse
Eel
Coelacanth
Shark
Stingray
Lamprey
Amphibians
Photo by ะะณะพัั ะัะบัะธะฝัะบะธะน on Pexels.com
Amphibians come in many shapes and sizesโfrom long-tailed salamanders to tailless frogs and even legless caecilians! Some are huge, like giant salamanders that grow to nearly six feet (two meters) long, while others are so tiny they could sit on your pinky finger. Amphibians also display striking colors, like the brightly patterned fire salamander or the brilliantly huedโbut toxicโpoison dart frog.
Amphibians all share a few key traits. One of their most distinctive features is their moist, scale-free skin. To stay hydrated, amphibians usually live in damp environments or near water. Their skin contains special mucus glands to keep it moist. Itโs also permeable, allowing water and gases to pass through. This means amphibians can absorb water and even breathe through their skin! However, most species also have lungs or gills for breathing.
Another trait of amphibians is metamorphosisโa dramatic transformation during their life cycle. For example, a tadpole with gills and a tail changes into an adult frog with lungs and legs. Finally, adult amphibians are carnivores, feeding on insects and other small animals.
Amphibian Traits
Spine
Cold-blooded
Moist skin with no scales
Skin surface breathing (may also have lungs and/or gills)
While reptiles and amphibians may look similar, they each represent a distinct vertebrate group. Reptiles can’t breathe through their skin like amphibians. Instead, reptiles always breathe through 1 or 2 lungs, and their skin is dry and scaly. Reptiles also never go through metamorphosis the way many amphibians do.
Reptiles are not the easiest group to define. There is a lot of diversity within this group. From legless snakes to shelled turtles and armored crocodiles, the reptile group has some incredible creatures. Unlike other classes of vertebrates, scientists now know that the group we call reptiles is not an isolated evolutionary lineage. This means that despite their many similarities, some members of the reptile group are not quite as closely related as people once thought they were. Additionally, we now know that birds descended from a reptile ancestor โ so in a way, birds and reptiles are relatives!
Turtles, tortoises, crocodilians, lizards, snakes, and tuataras are all types of reptiles. They live in freshwater, oceans, and on land. They come in all sizes: from the tiny Brookesia nana chameleon at less than an inch (~2 cm) in length, to giants like Komodo dragons and crocodiles.
The saltwater crocodile is the largest reptile on earth today, measuring over 20 feet (6 meters) long! In the past, even larger reptiles roamed the Earth (dinosaurs) but today they are extinct. All in all, there are over 10,000 amazing species of reptiles alive on Earth today.
Birds are a group of egg-laying, warm-blooded vertebrates with feathers, wings, and beaks. If you traced that family tree back far enough, youโd discover that birds evolved from theropod dinosaurs. Because of this shared ancestry, a sparrow is actually more closely related to a dinosaur than to a mammal, amphibian, or any other living vertebrate class. Scientists use these evolutionary relationships to decide which animals belong in the bird group.
Birds live on every continent, including Antarctica, and can be found in nearly every habitatโfrom forests and deserts to wetlands and open oceans. There are over 10,000 species of birds, and they range in size from tiny hummingbirds to towering ostriches. Birds also show remarkable diversity in behavior. Some migrate thousands of miles each year, while others stay in the same place their entire lives. Their colors, calls, and nesting styles vary just as much as their sizes and shapes.
Like birds, mammals are warm-blooded vertebrates. Mammals are unique because they have hair/fur and nurse their babies with milk. There are over 5,000 different species of mammals alive today. They live in freshwater, oceans, on land, and even take to the skies! They come in all sizes, from tiny creatures like the bumblebee bat to giants like whales. The blue whale is not only the largest mammal, but also the largest animal on earth!
Mammal Traits
Spine
Warm-blooded
Breathe air with lungs
Fur, hair, or whiskers (on all or part of the body, for at least part of its life)
Produce milk (in females)
Single lower jawbone
3 tiny earbones
Examples of Mammals
Mouse
Deer
Tiger
Whale
Otter
Bat
Armadillo
Kangaroo
Human
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Thereโs no need to scramble to put together the perfect lessons on vertebrates โ Iโve already created them for you! These sets include all the printable materials you need for studying vertebrate groups.
In this post, we’ll dive into the stages of the bird life cycle: egg, hatchling, nestling, fledgling, and adult. At the bottom of this post, you’ll find links to bird life cycle learning materials and more educational posts and activities related to birds. Get ready to take flight into the world of birds with your classroom!
Before we dive in:ย If youโre an educator planning toย teach bird life cycles, great learning resources are key to deepening understanding! I think you and your students will love myย bird life cycle mini study, which you can also find within my complete Bird Unit (plus youโll support my blog with your purchase! โค๏ธ)
Life Begins in an Egg
Baby birds hatch from eggs. Inside an egg, a chick develops while protected by a hard eggshell. The unborn chick is nourished by a yolk, which provides food as it grows.
Most birds lay their eggs in nests, which they build in trees, on the ground, on cliffs, or even on buildings. Nests come in several shapes and sizes. Some are tiny woven cups made of dried grass, while others are huge platforms constructed from sticks. Parent birds sit on the nest to keep the eggs warm, an act called incubation.
Hatching
When chicks hatch, they use a special bump on their bill called an egg tooth to crack open the eggshell.ย Newly hatched chicks are small, weak, and cannot care for themselves. They are sometimes called hatchlings. Many are born with their eyes sealed closed. They have only a few soft feathers called down to help keep them warm.
Growing and Fledging
Parent birds play a critical role in caring for their young chicks in the nest, sometimes called nestlings. They bring food, protect the nest, and keep chicks warm. As the chicks grow, they develop flying feathers and stronger muscles. Eventually, they leave the nest for the first time. This stage is called fledging. Young birds at this stage are known as fledglings. Even after leaving the nest, fledglings may still rely on their parents until they learn to find food and fly longer distances. As adults, birds may migrate, build their own nests, and establish territories.
More Bird Posts & Classroom Activities:
Continue learning about birds in your classroom with these educational posts and activities for kids:
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Salmon have one of the most incredible life cycles among fish. Unlike most fish, salmon live in two very different habitatsโfreshwater and saltwater. They begin their lives in cool, clear mountain streams, but migrate to the ocean where they spend much of their adulthood. Later, they make an epic journey back upstream to where they were born to lay eggs and start the cycle all over again.
Before we dive in:ย If youโre an educator planning toย teach salmon or fish life cycles, great learning resources are key to deepening understanding! I think you and your students will love myย salmon mini study, which you can also find within my complete Fish Unit (plus youโll support my blog with your purchase! โค๏ธ)
Life Begins in a Stream
A female salmon lays her eggs in a gravel nest in a freshwater stream. When the eggs hatch, the tiny fish are called alevins. They stay hidden among the gravel, sustained by the nutrients in their yolk sacs. Once the yolk sac is gone, they become fry and begin to feed and swim freely. As they grow, faint markings appear on their sidesโthese young fish are now called parr. They feed and begin defending small territories within the stream.
Salmon development – from egg to fry.
Journey to the Ocean
When the salmon are large and strong enough, they go through changes that prepare them for saltwater life. At this stage, they are called smolts. The smolts migrate downstream, swimming with the current, to the ocean. In the ocean, they will spend several years feeding on ocean prey and growing into adult salmon.
Returning Home
After maturing in the ocean, adult salmon return to the same stream where they were bornโa journey that can cover hundreds of miles! This journey is especially challenging because the fish are swimming into the current. They must navigate around obstacles like fast-flowing water, log jams, and even waterfalls!
Once they reach their birthplace, the spawning adults lay and fertilize eggs. Female salmon lay their eggs in gravel nests, where they will hatch and begin the next generation of salmon. After spawning, most salmon die, but their bodies provide nutrients that enrich the stream ecosystem.
Examples of female and male adult spawning salmon.
The role of salmon
Salmon are a key part of both ocean and land ecosystems. In the ocean, they serve as food for animals like sharks and seals. When they return to freshwater, they feed predators such as bears, eagles, and otters. Even after death, their bodies nourish the soil and plants near the streams, making salmon vital to the health of the whole ecosystem.
Salmon in a stream. Photo by Line Knipst on Pexels.com
Salmon face many challenges throughout their long journey. Dams can block their migration routes, making it hard for them to reach their spawning grounds. Competition with invasive fish species can also reduce the number of young salmon that survive to adulthood. Human activitiesโlike building cities and roads, farming, and miningโcan damage salmon habitats by changing stream flow, increasing pollution, and removing trees that shade and cool the water. Climate change adds even more stress, warming rivers and oceans, altering streamflow patterns, and shifting ocean currents that salmon depend on for food and navigation.
To help, people are taking action. Fish ladders and fish-friendly dams allow salmon to swim upstream more easily. Habitat restoration projects work to clean up streams and remove barriers to migration. Scientists are also studying how to protect salmon as the climate changes, ensuring these remarkable fish can continue their journey for generations to come.
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Thereโs no need to scramble to put together the perfect lesson on salmon or fish life cycles ย โ Iโve already created it for you! This fish unit includes all the printable materials you need for studying fish life cycles, salmon, and more.
Fish are one of the most diverse groups of vertebrates on Earth, but not all fish are built the same way. In fact, every speciesโwhether itโs a tiny goby or a massive whale sharkโbelongs to one of three major groups: jawless fish, cartilaginous fish, or bony fish. Understanding these groups can help students make sense of fish anatomy, evolution, and the incredible variety they see in todayโs oceans. Hereโs a quick, classroom-friendly guide to what makes each group unique.
Before we dive in: If youโre an educator planning to teach vertebrate groups, fish life cycles, or ocean biomes, great learning resources are key to deepening understanding! I think you and your students will love my complete Fish Unit. It’s full of fun activities, printable handouts, worksheets, and more (plus youโll support my blog with your purchase! โค๏ธ)
The sucker-like mouths of lampreys, a jawless fish.
Fish were among the earliest vertebrates to evolve, and some ancient fish lived long before jaws existed. Today, the descendants of those early jawless vertebrates survive as lampreys and hagfish.
Jawless fish share the following traits:
Gills
Live in water
Fins (various shapes, sizes, and numbers)
Skeletons made of cartilage, not bone
No jaws
A spine
Since they have no jaws, lampreys and hagfish must feed in some creative ways. For example, lampreys use a round, suction-like mouth with rasping teeth. Some species, like the sea lamprey, are parasites that attach to other fish and feed on their blood and body fluids. Their unusual anatomy makes them an important group for studying early vertebrate evolution.
Cartilaginous Fish (Chondrichthyes)
Like all cartilaginous fish, a hammerhead shark has a skeleton made of soft cartilage. Photo by Ben Phillips on Pexels.com
Unlike jawless fish, cartilaginous fish have a jaw. Jaws allow some fish to hunt and eat larger prey animals. For example, sharks are among the most fearsome predators of the ocean and hunt other fish with their jawed mouth filled with sharp, pointy teeth. Cartilaginous fish are named for their skeletons, which are made of soft cartilage – the material in your nose and ears – instead of hard bone.
Cartilaginous fish share the following traits:
Gills
Live in water
Fins (various shapes, sizes, and numbers)
Skeletons made of cartilage, not bone
Jaws
A spine
There are three main types of cartilaginous fish: sharks, skates, and rays. Though skates and rays don’t look much like other fish, they share a common ancestry and have traits that all fish share, like gills and fins.
Here are some examples of cartilaginous fish:
Great white shark
Leopard shark
Whale shark
Goblin shark
Manta ray
Common stingray
Common skate
Bony Fish (Osteichthyes)
Bony fish are found in many different habitats: from coral reefs in the ocean to flowing freshwater rivers. Photo by Francesco Ungaro on Pexels.com
What do salmon, seahorses, eels, and even your pet beta all have in common? They are all bony fish! This is a vast and diverse group of fish, with many deviations from the classic fish body plan that allow different fish to adapt to their unique habitats.
Bony fish share the following traits:
Gills
Live in water
Fins (various shapes, sizes, and numbers)
Skeletons made of bone, not cartilage
Jaws
A spine
There are two main subgroups within the bony fish group. They are lobe-finned fish and ray-finned fish. Lobe-finned fish have fins with internal bones that move more similarly to the limbs of tetrapods. Meanwhile, ray-finned fish have fins supported by many thin, bony filaments called rays.
There are tons of examples of bony fish. Here are a few:
Lobe-finned fish:
African lungfish
Australian lungfish
African coelacanth
Ray-finned fish:
Gar
Sturgeon
Salmon
Tuna
Clownfish
Seahorse
Pufferfish
Eel
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From tadpoles turning into frogs to caterpillars transforming into butterflies, metamorphosis is one of natureโs most incredible processes. Understanding metamorphosis helps students see how organisms grow, adapt, and survive in their environments. Whether you’re exploring amphibians, insects, or life cycles in general, this fascinating transformation is a perfect way to bring nature and science to life in your classroom.
๐A Note for Teachers ๐: If youโre an educator planning to teach metamorphosis and animal life cycles in your classroom, great learning resources are key to deepening understanding! You can find materials for teaching metamorphosis in my Amphibians Unit and Insects Unit, as well as my Aquatic Macroinvertebrates Unit – plus tons of other materials and activities for these fun topics! (And youโll support this blog with your purchase! โค๏ธ)
Metamorphosis is a process where an animalโs body changes form at different stages of its life cycle. Many insects and amphibians go through metamorphosis, developing in two or more distinct stages, like a legless tadpole becoming a frog or a wingless caterpillar transforming into a butterfly.
In contrast, reptiles, birds, and mammals (including humans) do not undergo metamorphosis. Consider human babiesโas we grow, we get bigger and taller, but our basic body shape stays the same. We donโt develop wings, extra limbs, or entirely new body parts like a butterfly or frog.
Amphibians and Metamorphosis
The word โamphibianโ means โdouble lifeโ, referring to how most amphibians begin their lives in water before transitioning to land. This transformation happens through metamorphosis. Take frogs, for example โ tadpoles swim using their tails and breathe underwater through gills. During metamorphosis, they grow limbs and lungs, allowing them to live on land as adults. Just like tadpoles transform into frogs, most salamanders start as aquatic, legless larvae before developing their adult forms.
Salamander Life Cycle Diagram
Most amphibians go through metamorphosis, but there are a few exceptions. Some species of caecilians, a group of legless amphibians, develop differently and donโt go through metamorphosis the way frogs and salamanders do.
Insects and Metamorphosis
Amphibians are not the only animals that go through metamorphosis. Many (though not all) insects go through metamorphosis too. One of the most classic examples is a butterfly. A butterfly starts life as a wingless larva called a caterpillar, a life stage in which the main goal is to eat and grow! After some time, the caterpillar stops munching and forms a chrysalis. During this stage, called the pupa stage, it doesn’t eat, but continues to develop. Finally, the winged butterfly emerges from its chrysalis – now it is an adult.
However, butterflies are far from the only insect to go through metamorphosis. Caddisflies, ladybugs, beetles, and ants are a few other examples of insects whose lives take place in three stages: larva, pupa, and adult. Insects like these with three distinct life stages go through what scientists call “complete metamorphosis“. In contrast, some other insects, like dragonflies and mayflies, go through “incomplete metamorphosis“. These insects only have two life stages: nymph and adult.
Why Metamorphosis?
Why change forms at all? Metamorphosis helps animals use different habitats and resources at each stage of life. For example, tadpoles live in aquatic habitats like ponds and eat plants, so they have gills, a small mouth, and a tail for swimming. But as they grow into adult frogs that hunt insects on land, they develop lungs, strong legs, and a wide mouth with a sticky tongue for catching prey.
Similarly, caddisflies, mayflies, dragonflies, and other aquatic insects begin their lives in water as larvae or nymphs. This allows them to feed on aquatic plant matter, detritus, or small organisms found in habitats at the bottoms of streams and ponds. As they go through metamorphosis, these insects emerge from the surface of the water as winged adults. After this, they use their wings to take advantage of a new habitat above the surface. For example, adult dragonflies are ferocious aerial predators of other insects. Contrastingly, adult mayflies do not eat at all, but simply use their short adult life stage to fly around and find a mate.
Finally, consider butterflies. Unlike frogs and aquatic insects, a butterfly lives on land for its whole life. However, butterflies use different food sources at different stages. For example, the monarch butterfly is in a close symbiotic relationship with the milkweed plant. As a caterpillar, the monarch eats the milkweed leaves. After metamorphosis, the adult butterfly eats a different part of the milkweed plant – the nectar of the milkweed flowers. As an added benefit, when the adult butterfly drinks flower nectar, it pollinates milkweed plants, which helps the plants reproduce. Thanks to the butterfly’s pollination services, a new generation of milkweed plants will grow, providing leaves for future caterpillars to eat!
A monarch butterfly caterpillar munches on milkweed.
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Whether you’re teaching your students about the metamorphosis of amphibians or insects, I’ve got the perfect learning resources for you! These sets include all the printable materials you need for studying amphibians and aquatic insects – including life cycle diagrams and much, much more!
Amphibians are some of the most fascinating creatures on Earth, bridging the gap between water and land with unique adaptations. Understanding amphibian traits can help students grasp key biological concepts like life cycles, metamorphosis, and environmental adaptations. Whether you’re teaching about frogs, salamanders, or caecilians, exploring what makes amphibians special is a great way to spark curiosity about the natural world.
๐A Note for Teachers ๐: If youโre an educator planning to teach amphibians, great learning resources are key to deepening understanding! I think you and your students will love my complete Amphibian Unit (plus youโll support my blog with your purchase! โค๏ธ)
Before we dive into the traits of amphibians, it helps to answer the question “what are amphibians?”. Amphibians are a group of vertebratesโanimals with backbonesโthat share some key traits. There are seven classes of vertebrates on Earth: amphibians, birds, mammals, reptiles, and three types of fish.
But how do scientists know which animals belong in each class? It all comes down to family trees! Each class of vertebrates shares a common ancestor from long ago. If you traced their lineage back far enough, youโd find that all amphibiansโfrogs, salamanders, and moreโdescend from the same ancient relative. Thatโs why a salamander is more closely related to a frog than to a reptile like a lizard.
Thanks to their shared lineage, amphibians share some characteristics. In this post, we’ll discover some key amphibian traits…
A Backbone
Like all vertebrates, amphibians must have a backbone. A backbone is actually made of many individual, smaller bones called vertebrae, all stacked up in a flexible column. Amphibiansโ spines help us tell them apart from invertebrate (backbone-less) creatures like insects and mollusks.
Cold-Blooded
Ever wonder why you see a frog sitting out on a lily pad in the sun? Amphibians are cold-blooded or ectothermic animals, which means their body temperature depends on the temperature of the air or water around them. They must rely on external (outside of themselves) heat sources to stay warm rather than making their own body heat.
When amphibians need to warm up, they sun themselves. If they get too hot, they go into cool water, underground, or find shade. Because they rely on external heat sources, their temperature varies a lot. Amphibians, reptiles, and most fish are cold-blooded animals.
Moist, Permeable Skin
One of their most distinctive features is their moist, scale-free skin. Amphibians, even the ones that look bumpy, like toads, never have scales. This is one of the key differences between amphibians and reptiles.
To stay hydrated, amphibians usually live in damp environments or near water. Their skin contains special mucus glands to keep it moist. Itโs also permeable, allowing water and gases to pass through. This means amphibians can absorb water and even breathe through their skin! However, most species also have lungs or gills for breathing.
Metamorphosis
Salamander Life Cycle Diagram
Another trait of amphibians is metamorphosisโa dramatic transformation during their life cycle. For example, a tadpole with gills and a tail changes into an adult frog with lungs and legs.
Most amphibians go through metamorphosis, but there are a few types of amphibians that are exceptions. Some species of caecilians, a group of legless amphibians, develop differently and donโt go through metamorphosis the way frogs and salamanders do.
Carnivorous
Finally, all adult amphibians are carnivores. Often, they hunt and eat small invertebrates – little animals without a backbone – like insects and worms. However, some large amphibians like bullfrogs will even hunt small vertebrates like smaller amphibians, reptiles, and even mammals like mice.
While adult amphibians are carnivores, larval amphibians often are not. This is because before going through metamorphosis, they are more suited to eating plant matter. For example, a tadpole lives in a pond and eats plant matter before it grows up into a frog that eats insects.
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Thereโs no need to scramble to put together the perfect amphibians lesson โ Iโve already created it for you! This set includes all the printable materials you need for studying amphibians.
If you enjoyed learning about amphibian traits in this post, I know you will love trying my other printable science and nature units in your classroom!
Amphibians are a diverse group of vertebrate animals. They come in many shapes and sizesโfrom long-tailed salamanders to tailless frogs and even legless caecilians! Some are huge, like giant salamanders that grow to nearly six feet (two meters) long, while others are so tiny they could sit on your pinky finger. Amphibians also display striking colors, like the brightly patterned fire salamander or the brilliantly huedโbut toxicโpoison dart frog. In this post, we’ll explore the different types of amphibians – some you’ve probably seen before, and perhaps a few you’ve never heard of!
๐A Note for Teachers ๐: If youโre an educator planning to teach amphibians, great learning resources are key to deepening understanding! I think you and your students will love my complete Amphibian Unit (plus youโll support my blog with your purchase! โค๏ธ)
There are 3 main types of amphibians: frogs, salamanders, and caecilians. Each has its own unique characteristics, described below.
Frogs and Toads
Class: Amphibia
Order: Anura
Key traits
Frogs and toads are amphibians with four limbs and no tails as adults. They also have powerful hind legs and vocal sacs for croaking. Frogs and toads start their lives in water as aquatic larvae called tadpoles. As tadpoles, they have gills and a tail for swimming. As frogs develop, they grow lungs and most species can come onto land. There are, however, some frogs that are aquatic as adults, such as African clawed frogs.
But even adult frogs like to live in damp habitats to help keep their moist skin from drying out. Frogs, like all amphibians, have moist skin rather than scales – one of the differences between reptiles and amphibians. Their skin is permeable, allowing them to drink water and breathe air through their skin.
There are about 5,000 different species of frog worldwide! They are found on 6 of 7 continents (everywhere but Antarctica).
Salamanders
Class: Amphibia
Order: Urodela
Key traits
Salamanders are amphibians with long, thin tails and usually four limbs. Like all amphibians, they have moist skin that they can breathe through. Most salamanders also have gills, lungs, or even both at different stages of their life cycle. Like frogs, most salamanders go through metamorphosis. The larvae are often aquatic, with no limbs, tails for swimming, and frilly-looking external gills around their necks. Adults may live in water, on land, or both, depending on the species. Like all amphibians, adult salamanders are carnivores – often they eat small invertebrates.
Perhaps you’re wondering, what is the difference between a salamander and a newt? A newt is one type of salamander. So while all newts are salamanders, not all salamanders are newts.
Examples of Salamanders
Tiger salamander
Giant Salamander
Newt
Axolotl
Amphiuma
Fun Facts
Salamanders struggle to lift their bodies off the ground due to the position of their limbs on the sides of their bodies. To walk on land, they must wiggle from side to side while dragging their bodies across the ground.
The axolotl is a species of salamander that never grows up (sort of)! Even as an adult, it lives in water and has gills like a larva.
Caecilians
Class: Amphibia
Order: Gymnophiona
Key traits
The third type of amphibian is caecilians. If you’ve never heard of them or seen one, don’t worry! They are only found in the tropics, and they live underground, burrowing in the soil.
Caecilians are different from other amphibians in several ways. They have no legs, and long, worm-like bodies with grooves or rings that look like segments. Furthermore, caecilians don’t go through metamorphosis like frogs and salamanders.
Fun Facts
Though they have no legs, caecilians evolved from a legged ancestor. Over many generations, they lost their legs since they didnโt need them to survive in their habitat.
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Mammals are a special group of creatures with some unique features. Mammals are a huge and diverse group of animals. They live on land, in freshwater, in oceans, and even take to the skies! They come in all sizes, from tiny creatures like the bumblebee bat to giants like whales. Mammals might seem very different from one another, but they share some special traits that help us distinguish them from other animals.
Mammals are part of a bigger category of animals called vertebrates, which means they all have a backbone. There are seven different groups, or classes, of vertebrates on Earth. These include amphibians, birds, mammals, reptiles, and three kinds of fish. In this post, we’ll learn more about the traits that make mammals unique from their other vertebrate relatives.
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First, female mammals produce milk to feed their young. This trait is unique to mammals: none of the other vertebrate groups make milk. Milk comes from special mammary glands in female mammals only.
Since mammals nurse their young, the mother must stick around after a baby mammal is born. For this reason, mammal mothers are very involved parents. Parental care is taken to the extreme in a sub-group of mammals called marsupials (e.g., kangaroos and opossums). Not only do they nurse their babies, but they also carry them around in a special pouch or on their backs or bellies.
Other types of mammals called placentals and monotremes don’t carry their babies around. Instead, some hunker down in a den or burrow with their newborn babies. For example, foxes and bears give birth to their babies in dens. Other mammal babies, like horses and elk, are born ready to start walking and even running. Though mammal babies vary in their abilities and needs, they all require milk from their mothers.
Breathe Air With Lungs
Third, all mammals breathe air through their lungs โ even the mammals that live in water must come to the surface to breathe. Despite their excellent swimming skills, whales, otters, seals, manatees, dolphins, and walruses are all mammals and come to the surface to breathe air.
However, these animals can all hold their breath for much longer than you or me. While a human might be able to hold their breath for about a minute, some marine mammals can hold their breath for an hour or more! For example, an elephant seal can hold its breath for up to two hours! However, if they cannot get to the surface to breathe for some reason, a seal (or any mammal) can drown. They do not have gills like fish and sharks.
Hair or Fur
Mammals must have hair or fur on some part of their body for at least part of their lives. You might be saying “Now wait a minute… what about marine mammals like whales?” Even marine mammals that appear hairless, like whales, are born with sensory hairs (whiskers) on their faces. Some species of whales lose these whiskers as they grow older.
From the sensory whiskers of a whale to the thick fur of a polar bear, there’s a huge variety of hairstyles among mammals. Hair and fur may serve several different purposes. Often hair and fur are for staying warm, especially among animals that live in temperate and polar climates. In warmer places, hair and fur help protect a mammal’s skin from intense sun. Hair and fur may also have patterns that help an animal camouflage.
Warm-blooded
Mammals are warm-blooded (also known as endothermic), which means they make their own body heat and maintain a constant temperature. Mammals are not the only vertebrates that are warm-blooded. Birds and even some fish are warm-blooded too.
You may be wondering: what does it mean to be warm-blooded? Warm-bloodedanimals make enough body heat to keep a relatively constant body temperature. For example, most humans maintain a constant body temperature of around 98ยฐF (37ยฐC). This takes a lot of energy, which comes from eating food.
Many warm-blooded animals have thick fur or feathers to help insulate their body โ the same way a thick sweater keeps you warm by trapping your body heat.ย If a warm-blooded animal gets too warm, it may sweat or pant to cool off. Can you think of any mammals that sweat or pant?
Skeletal Features
Finally, mammal skeletons have some key characteristics. You already know that mammals are vertebrates, which means they have a backbone. Additionally, mammals always have hinged jaws with a single lower jawbone. All mammals also have three tiny ear bones, sometimes called the hammer, anvil, and stirrup.
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Reptiles are a cool group of critters โ and not just because they are cold-blooded! They are part of a bigger category of animals called vertebrates, which means they all have a backbone. There are seven different groups, or classes, of vertebrates on Earth. These include amphibians, birds, mammals, reptiles, and three kinds of fish.
Reptiles are not the easiest group to define. There are many types of reptiles with diverse characteristics and behaviors. From legless snakes to shelled turtles and armored crocodiles, the reptile group has some incredible creatures. Unlike other classes of vertebrates, scientists now know that the group we call reptiles is not an isolated evolutionary lineage. This means that despite their many similarities, some members of the reptile group are not quite as closely related as people once thought they were. Additionally, we now know that birds descended from a reptile ancestor โ so in a way, birds and reptiles are relatives!
Don’t fret if all this seems confusing. Luckily, all reptiles share a few unique traits that can help us distinguish them from other animals. In this post, you’ll read about four traits that all reptiles have!
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Like all vertebrates, reptiles must have a backbone. A backbone is actually made of many individual smaller bones called vertebrae all stacked up in a flexible column. Reptiles’ spines help us tell them apart from invertebrate (backbone-less) creatures like insects and mollusks.
Apart from their spines, reptiles’ skeletons don’t share much in common with each other. While all reptiles have jaws, some have a single jawbone, while others have flexible jaws made of multiple bones. Not all reptiles even have the same number of limbs. While turtles, crocodiles, and most lizards have four limbs, snakes have no limbs at all.
Breathe Air With Lung(s)
All reptiles breathe. However, not all reptiles have two lungs. Interestingly, many snakes only have one working lung. Even the reptiles that live in water have lungs. Despite their excellent swimming skills, sea turtles, water snakes, and marine iguanas all come to the surface to breathe air.
However, some of these animals can all hold their breath for much longer than you or me. While a human might be able to hold their breath for about a minute, a sea turtle might hold its breath for as long as 2 hours when resting. However, if they cannot get to the surface to breathe for some reason, sea turtles (like any reptile) can drown. They do not have gills like fish and sharks.
Scales or Scutes
Reptile scales (left) and scutes (right)
A reptile has scales or scutes covering its body. You may already be familiar with scales. Scales are overlapping, shingle-like surfaces that make up a snake or lizard’s skin. Scales are part of the epidermis or outer skin. They are made of keratin, like your fingernails. A reptile will shed and regrow its scaly skin multiple times throughout its life. Reptiles are not the only animals with scales. Fish have scales too.
You might be wondering: what is a scute? A scute is a thick, armored plate found in turtle shells and the skin of crocodiles and alligators. Reptiles are not the only animals with scutes. Scutes also make up the rough-textured surface of birds’ legs.
While scales and scutes are not unique to reptiles, they are helpful traits that can help us tell the difference between a reptile and an amphibian. Amphibians never have scales or scutes – instead, they have distinct moist, smooth skin.
Some reptiles have scales that help them blend in or camouflage, like a chameleon. Learn more about camouflage by reading this post about the types of camouflage or trying this fun camouflage lab activity.
Cold-blooded
Ever wonder why you see snakes and lizards sitting out in the sun? Reptiles are cold-blooded or ectothermic animals, which means their body temperature depends on the temperature of the air or water around them. They must rely on external (outside of themselves) heat sources to stay warm rather than making their own body heat.
When reptiles need to warm up, they sun themselves. If they get too hot, they go underground, into cool water, or find shade. Because they rely on external heat sources, their temperature varies a lot. Reptiles, amphibians, and most fish are cold-blooded animals.
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