Vertebrates- Animals with Backbones


Enjoy the FREE printable vertebrate packet below, with a poster, study guide and short quiz!

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.

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. Usually fish have 4 gill slits, but sharks and some others have 5 or more. Gills have comb-like filaments that filter oxygen out of the water and into their bloodstream, and carry water filled with carbon dioxide back out of their bodies.
Fish have fins which help them paddle and maneuver through water. They also have scales that often reflect light or give fish their color. Scales are like plates that protect the bodies of fish. You can actually determine the age of fish by counting the rings on their scales! Fish are also cold blooded animals which means their bodies become 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, salamanders, and caecilians 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. (Consider Genesis 3:14.) Scientists believe most dinosaurs were reptiles.

Mammals (Hair, Milk, Live Birth, Warm blooded)
Mammals can be bears, bunnies, or even whales. All mammals have hair or fur that help them maintain their warm blooded bodies. Mammals give birth to live young, most supported in the womb by a placenta and born fully developed. Marsupials, however, are born very small and further develop in their motherʻs pouch. The platypus and echidna are the exception to the mammal world, laying soft eggs. All mammals have lungs and breathe air, so most mammals live on land, but some live in the sea. There are five types of marine mammals, including pinnipeds (seals, sea lions), cetaceans (whales, porpoises), sea otters, sirenians (manatees), and polar bears. Mammals get their names from mammary glands which produce milk. All mammals produce milk in some way to feed their babies.

Birds (Feathers, Beak, Eggs)
Birds can be as tiny as a hummingbird or as large as an ostrich. All birds have feathers. Contour and flight feathers have an interlocking structure like velcro that makes them perfect for flight but also repels water. Down feathers store heat for their warm blooded bodies. Filoplumes are sensory feathers that are believed to provide information about wind, air pressure and feather movements to aid in flight. Though all birds have feathers, 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. Birds bones are lightweight and hollow which makes them light and helps them fly. All birds have a beak. Beaks come in many shapes and sizes, and are used different purposes. Because birds donʻt have teeth they use their beaks for either tearing meat, breaking seeds, sipping nectar, fishing, or finding and eating insects.

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!

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