Fish are vertebrates and therefore have backbones. Fish are sometimes observed with curved backbones. This is attributed to a variety of factors, including lack of vitamin C, injury, birth defect, temperature change whil... More »

All species of birds have backbones because birds are vertebrates. The animal kingdom can be organized by grouping classes of organisms together based on key physical characteristics. Whether or not an organism has a bac... More »

Sharks do not have a backbone because their skeletal system is made up of a softer cartilage, just like all the other fish that belong to the Chondrichthyes class. The cartilage found in sharks is not as hard as a real b... More »

All fish are vertebrates, which means they have a backbone, and are cold-blooded, which means their internal temperature changes to match the temperature of their surroundings. There are 25,000 known species of fish, whi... More »

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Some fish have bones, including full backbones and articulated skeletons, while other fish do not have bones. The bony fish, as they are known, belong to the class Osteichthyes. The other class of fish is known as Chondr... More »

One type of fish that starts with the letter "X" is the X-ray Tetra, known for its translucent skin that makes its backbone visible, according to OneKind, an animal protection charity. The fish also is called the Golden ... More »

Members of Chordata may live in aquatic environments if they are invertebrate fish or in land environments if they are vertebrates. They include marine animals, amphibians, birds, reptiles and mammals. There are several ... More »