Kids Research Express

. Vertebrate, animal with a backbone, or spinal column, made of interlocking units called vertebrae. This strong but flexible structure supports the body and anchors the limbs, and it also protects the nerves of the spinal cord. Vertebrates include fish, amphibians, and reptiles, as well as birds and mammals. In all vertebrates, the spinal column forms part of a complete internal skeleton. Unlike the hard external skeleton covering an insect, which is periodically shed as the insect grows, a vertebrate’s internal skeleton can grow gradually along with the rest of the body. There are over 40,000 species of vertebrates, which scientists classify into five groups: (1) fish , (2) amphibians , (3) reptiles , (4) birds , and (5) mammals . Scientists divide fish into three groups based on their anatomy: jawless fish, cartilaginous fish, and bony fish. The other vertebrate groups are made up of tetrapods, which have lungs and generally live on land.

Vertebrate, animal with a backbone, or spinal column, made of interlocking units called vertebrae. This strong but flexible structure supports the body and anchors the limbs, and it also protects the nerves of the spinal cord. Vertebrates include fish , amphibians , and reptiles , as well as birds and mammals. In all vertebrates, the spinal column forms part of a complete internal skeleton . Unlike the hard external skeleton covering an insect, which is periodically shed as the insect grows, a vertebrate’s internal skeleton can grow gradually along with the rest of the body. Vertebrates make up only about 2 percent of the animal species, and they belong to just 1 of more than 30 phyla, or overall groups, in the animal kingdom. Despite this, vertebrates occupy a dominant position in almost all habitats and are by far the most familiar animals. When asked to name an animal at random, most people identify a type of vertebrate. There are several reasons why vertebrates are so successful a

. There are over 40,000 species of vertebrates, which scientists classify into five groups: (1) fish , (2) amphibians , (3) reptiles , (4) birds , and (5) mammals . Scientists divide fish into three groups based on their anatomy: jawless fish, cartilaginous fish, and bony fish. The other vertebrate groups are made up of tetrapods, which have lungs and generally live on land. Jawless fishes -> Cold-blooded animals that live in water. These fishes have no bone structure and their sole support is from a simple cartilaginous rod known as the notochord. Unlike other vertebrates, these fishes do not have opposing jaws. They have round, sucker-like mouths and use tongues with embedded teeth that scrape tissue from prey. Jawless fishes have primitive breathing openings that provide oxygen to the blood. They reproduce by laying eggs. - Examples: Hagfish, lamprey Cartilaginous fishes -> Cold-blooded animals that live in water. Their notochord is surrounded by rings of cartilage known as