What is a vertebrate?
The vertebrates are a group of animals. They all have a “backbone” made of a number of “vertebra”, containing an important nerve. The vertebrates are the largest group of the chordates – there are over 57000 species known, mostly fish. The world’s largest animal is a vertebrate – the Blue Whale.
What kinds of vertebrates are there?
The average person will divide vertebrates into fish, amphibians, reptiles, birds and mammals. Scientists mostly follow this, except that the fish are split into a large number of groups, (or “classes”). Also, some of the dinosaurs were so different from others that they were given their own class.
- The most well-known classes of fish are the Condrichthyes (cartiligenous fish) and the Bony fish, which includes the Actinopterygii and the Sarcopterygii. Many of the other classes are completely extinct now. Scientists classify fish into the following classes.
- The Acanthodii, sometimes called Spiny Sharks, are an extinct group of fish that had some characteristics of Cartiliginous fish, and others of bony fish.
- The Actinopterygii are the largest class of fish, in fact, the largest class of vertebrates! There are 27000 species of these, “ray-finned” fish, living in both sea and fresh water.
- The Cephalaspidomorphs are a group of extinct jawless fishes. Actually, scientists are divided as to what animals exactly should belong to this group – some say the lampreys should be included, others disagree.
- The Condrichthyes are the cartiligenous fishes, including sharks and rays. These fish don’t have true bone, instead, their skeleton is made of cartilige.
- The Conodonts : a group of extinct worm-like animals, known mainly from their fossilized teeth.
- The Hyperoartia is the class of the Lampreys, a group of eel-shaped sea animals, that are so different from fish, that scientists put them in a different group altogether.
- The Myxini : these are the Hagfish – they look a bit like eels, and can tie themselves into knots.
- The Placoderms : another group of extinct fish, which had hard plates to protect their heads.
- The Pteraspidomorphs : a group a extinct fish, which didn’t have jaws.
- The Sarcopterygii, or lobe-finned fish, include the lungfish, and the once-thought-extinct coelacanths.
- The other classes of vertebrate are
- The amphibians (Amphibia). These are the frogs, newts, toads, salamanders, axolotls. These are vertebrates that can breathe both air and water.
- The reptiles (Sauropsida). These are the turtles, lizards, snakes and other land vertebrates with scales.
- Synapsida is a group of creatures most of us would call dinosaurs, but which differed from other dinosaurs so much they were given their own class.
- The birds (Aves). Mostly feathered, and mostly able to fly.
- The mammals (Mammalia). These warm-blooded creatures mostly have hair, and all give milk to their young. The world’s largest vertebrate – indeed, the world’s largest animal – is a mammal.
What is the world’s largest vertebrate?
The world’s largest vertebrate in every way is the Blue Whale. It can grow up to 30 metres (100 feet) long or more, and weigh around 140 tonnes – that’s 140000 kg, or 300000 pounds! It is even bigger than the largest dinosaurs ever were. Sadly, it almost went the way of the dinosaurs in the 20th century, due to whaling. Hunting of Blue Whales was banned in the 1960s, and finally ended in the 1970s. Even now, the population of blue whales is still less than 1% of what it was before whaling began.