Flightless birds? Swimming Mammals? How awkward vertebrates fit

Vertebrates are animals with a backbone (think vertebrae). These are the creatures we usually think of when we think of animals. Vertebrates have tremendous diversity in shape, size, ability, and characteristics. They are truly wondrous creatures! The 5 classes of vertebrates are:
Fish, Amphibians, Reptiles, Mammals, and Birds.
I personally love the vertebrates, as many cute animals are part of this group— including my adorable human children. For a long time I wondered things like… what is the difference between an amphibian and a reptile? Or what makes a penguin a bird when it can’t swim? And why is a whale a mammal, and not fish?

As we study this different groups we find the answers to these questions!

Why are dolphins and whales mammals?

Mammals give birth to live young, feed them milk from mammary glands, breathe air, and have hair. So why are dolphins and whales mammals? You can probably figure out from the my short list above— whales and dolphins are born alive, and they get mother’s milk— even under water! And even though they spend their entire lives in the sea, they have lungs and breathe air. They can hold their breath for a very, very long time, but they have blow holes on their heads to catch a breath by touching the surface of the water. But wait— do whales and dolphins have hair? Why yes, they do! They have very little, but they do indeed have tiny little hairs. Whales have tiny hairs on their heads, and dolphins have whiskers!

What is the difference between a reptile and an amphibian?

How is it a lizard isn’t in the same group as a salamander? They look awfully similar! But a lizard is a reptile, and a salamander is an amphibian.

Both Reptiles and Amphibians lay eggs, are cold blooded creatures, and have four legs (snakes and caecilians being the exception). Yet these two group have some big differences. Reptiles have claws and scales, while amphibians have slimy skin and undergo metamorphosis.

Amphibians are named for their two lives— “amphi” means both— and these creatures are born like fish and mature to be land animals. Amphibians start as eggs laid in water, and like a fish, hatch swimming in water. Most amphibians even have gills— but not for long. As they grow, they develop lungs and live on the land. So while lizards and salamanders look a lot alike, they live very different lives.

How is a penguin a bird if it can’t fly?

Birds have feathers, lay eggs, and have beaks. Most birds live half in their nests, and half flying in the skies. However some birds don’t fly— like ostriches and penguins. Penguin feathers are coated with oil which resists the water so they can swim. Their different types of feathers—plumules, filoplumes, and after feathers— are perfectly suited to keep them warm in icy waters, and to help them “fly” underwater. These birds can live in the coldest climates on earth.

The blue part of the bird skeleton is the keel.

Ostriches, cassowaries, emus, rheas, and kiwis can’t fly because they don’t have a keel. The keel anchors the birds pectoral wing muscles together so they can get the lift they need to fly. These birds also don’t have the enough interlocking wing feathers for flight. Interlocking wing feathers are aerodynamic and perfectly suited to press against the air to catch flight. Instead these birds use their wings for balance, steering, and keeping cool.

I hope you found some answers to your questions and had fun learning about these unique animals!

You can learn all about vertebrates in the free PDF lesson below, or order the new Jolie Canoli Life Science book!

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FREE printable about vertebrates includes a poster, study guide, and short quiz!

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Check out the Life Science Workbook!

Jolie Canoli Life Science is a workbook full of playful illustrations, easy-to-understand science lessons, playful quizzes, and educational activities.  Perfect for elementary students studying Classification of Living Things, Biology, and Botany. 

Vertebrates- Animals with Backbones

See these animals giving one another a back rub? They are all vertebrates. Vertebrates are animals with backbones (vertebrae). The 5 classes of vertebrates are: Fish, Amphibians, Reptiles, Mammals, and Birds.

Fish (Gills, Fins, Scales, Cold Blooded)

Fish are the only group of vertebrates that live entirely in water. All of them have gills, which is special breathing tissue that allows fish to breathe oxygen underwater. Fish have fins which help them paddle and maneuver through water. They also have scales that protect their bodies like armor. You can actually determine the age of fish by counting the rings on their scales! Fish are cold blooded animals which means their blood becomes cooler or hotter depending on the temperature of the water. Fish will swim slowly below the ice during winter, or even sleep in icy waters. Some fish actually produce antifreeze molecules called glycoprotein that keep their bodies from freezing in really cold temperatures!

Amphibians (Slimy skin, Metamorphosis, Four Legs, Cold Blooded) 

Amphibians like frogs, toads, and salamanders are born in water and develop the ability to live on land. This means almost all amphibians will go through metamorphosis. (Think of how tadpoles become frogs.) Most are born with gills and then develop lungs and four legs, though caecilians do not have legs. They have permeable, wet, slimy skin that absorbs water and oxygen, and usually have webbed feet. Amphibian eggs have no shell, but are covered in a jelly-like substance. Amphibians are also cold blooded, so they are quick and active when it is warm, but slow and sluggish when it is cold.

Reptiles (Scales, Eggs, Four Legs, Cold blooded)

Reptiles like turtles, snakes, crocodilians, and lizards are covered with scales, and usually have claws. Reptiles are cold blooded creatures and lay eggs. They are tetrapods, meaning they have four legs, or in the case of snakes, “descended” from creatures with four legs. Interestingly there are a number of snake fossils with legs, and some pythons have vestiges of legs. 

Mammals (Hair, Milk, Live Birth, Warm blooded)

Mammals can be bears, bunnies, or even whales. Mammals give birth to live young. Mammals get their names from mammary glands that produce milk to feed their newborn babies. All mammals have hair or fur that helps them maintain their warm blooded bodies. All mammals have lungs and breathe air, so most mammals live on land, but some live in the sea. These marine animals include pinnipeds (seals, sea lions), cetaceans (whales, porpoises), sea otters, sirenians (manatees), and polar bears.

Birds (Feathers, Beak, Eggs)

Birds can be as tiny as a hummingbird or as large as an ostrich. All birds have feathers, though not all of them fly. Penguins have feathers, but they swim. Ostriches and emus have large feathers, but their sternum is not attached to their pectoral muscles, making them too weak to fly. All birds have a beak. Beaks come in many shapes and sizes, and are used for different purposes, including tearing meat, breaking seeds, sipping nectar, fishing, or finding and eating insects.

Enjoy the FREE printable vertebrate packet more fun illustrations, a poster, study guide, and short quiz!

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For more fun consider studying:

• Different types of feathers

• Four types of fish scales (Placoid, Cosmoid, Ganoid, Cycloid)

• Explore reptiles!

• Go find some frogs at your local pond! Be sure to wash your hands…

• Try making a list of the mammals that live in your neighborhood. Or try one of these cool ideas!

• Visit the local pet shop and see if you can identify what creatures belong in which vertebrate class!

Life Science Set

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