Vertebrata

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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

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 and so noticeable. One has to do with their size. Invertebrates—that is, animals without backbones, such as worms, shellfish, and insects—tend to be small and slow moving. This is because they lack effective ways to support a large body and the muscles needed to power it. Vertebrates, on the other hand, have evolved a much more versatile support system. Their skeletons can be adapted for use in many different ways and work just as well in an animal weighing 4 tons as in one weighing 113 g (4 oz). As a result, vertebrates have been able to develop bigger, faster bodies than invertebrates.

Vertebrates also have highly developed nervous systems. With the help of specialized nerve fibers, they can react very quickly to changes in their surroundings, giving them a competitive edge.

See Types of Vertebrates

Types of Vertebrates

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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 vertebrae. The remainder of the skeleton is also cartilaginous rather than bony. They have breathing organs called gills that provide oxygen to the blood. Cartilaginous fishes have powerful jaws for grasping prey. Reproduction varies depending upon the species. Some fish produce live young, while others lay eggs outside of the female body.- Examples: Sharks, skates, rays, chimaeras

Bony fishes -> Cold-blooded animals that live in water. Their skeleton is made of bone, and most bony fishes also have an internal bladder that aids in buoyancy. The anatomy of these fishes varies greatly, but typically includes fins, scales, a two-chambered heart, and gills. Bony fishes reproduce by laying eggs. In some species the eggs develop inside the female, who then give birth to live young. Examples: Sturgeon, herring, salmon, perch, cod, coelacanth

Amphibians -> Cold-blooded animals that live some part of their life on land but usually must breed and develop from egg to larvae to adult in water. Most amphibian larvae use gills to breathe underwater. These gills are then replaced in adults by lungs for breathing air. Their permeable skin acts as an additional breathing organ by permitting oxygen exchange. Their skin also permits water to pass in and out, requiring amphibians to stay nearby a water source so that their bodies do not dry out. Amphibians were the first animals with backbones to adapt to life on land. – Examples: Frogs and toads, salamanders, newts, caecilians

Reptiles - > Cold-blooded animals with an outer covering of scales or bony plates that prevents their bodies from drying out when not near water. Reptiles reproduce by laying eggs protected by shells or by giving birth to live young. They do not have a larval stage. Mostly land-dwellers, they breathe air using lungs. – Examples: Snakes, crocodiles, alligators, lizards, turtles, tortoises

Birds -> Warm-blooded animals whose body is covered with feathers. Birds have wings that in most cases help them fly. A number of adaptations make flight easier, including a lightweight skeleton in which many major bones are hollow and a furculum, or wishbone, that absorbs the shock of wing motion during flight. Birds reproduce by laying eggs protected by shells. – Examples: Penguin, flamingo, eagle, turkey, thrush, parrot

Mammals -> Warm-blooded animals, the females of which have milk-secreting organs that they use to feed their young. Mammals have highly developed brains, giving them an intelligence unmatched by any other group of animals. Most mammals reproduce by giving birth to live young. They are the only animals with hair, and they have specialized teeth that make it possible to eat a wide variety of plants and animals for food. – Examples: Platypus, kangaroo, bat, lion, wolf, mouse, seal, antelope, cow, dolphin, whale, lemur, monkey, ape, human