This document summarizes the classification of vertebrate animals. It describes five groups: fish, amphibians, reptiles, birds, and mammals. For each group, it outlines key distinguishing characteristics, such as their skeletal structure, skin/scales, limbs, reproduction methods, temperature regulation, habitats and examples of common animals in each group. It also describes some subgroups within each main category, such as bony fish vs. cartilaginous fish, and anurans vs. urodeles for amphibians.

1. Pablo León Cruz www.biogeosfera.es
KINGDOM ANIMALIA: VERTEBRATES

2. The classification of the animals

3. The classification of the animals
Vertebrate Animals
The vertebrate animals have a spinal column. All have an
internal skeleton (endoskeleton).
 Fish
 Amphibians
 Reptiles
 Birds
 Mammals

4. Fish
Fish are vertebrate animals that live in aquatic environments,
either freshwater or saltwater.
Características de los peces
 Their body is covered in scales, except for the head.
 Their body is fusiform to travel through the water.
 The limbs are transformed into fins: dorsal, pectoral, ventral, anal and
caudal.
 They have a lateral line, a sensory organ that detects movement and
vibrations in water and serves to orient themselves and to detect their
preys.
 They are poikilotherms: they do not regulate their body temperature.
 Almost all are carnivorous.
 They breathe using a gill system.
 They reproduce sexually with external fertilization.
 They are oviparous: they reproduce through eggs.
 They live in aquatic environments.
 They are classified into osteichthyes and chondrichthyes.

5. Fish
Osteichthyes, the bony fish
 They have a bony skeleton.
 Their skin is covered with scales.
 They have a swim bladder.
 The gills are protected by an operculum.
 Their mouths are position in the front of their bodies.
 The caudal fin is homocercal (symmetrical).
 They represent most fish: tuna, trout, sardines, anchovies, gilt-head
bream, perch…

6. Fish
Bony fish

7. Fish
Bony fish

8. Fish
Chondrichthyes, the cartilaginous fish
 They have a cartilaginous skeleton.
 Their skin is covered with denticles.
 They don't have a swim bladder.
 The gills are protected by brachial slits.
 They have their mouths in a ventral position.
 The caudal fin is heterocercal (asymmetrical).
 They're a small group of fish: shark, dogfish, mako shark, stingrays,
skate, sawfish…

9. Fish
Cartilaginous fish

10. Fish
Cartilaginous fish

11. Fish
Scales Denticles

12. Amphibians
Amphibians are vertebrate animals that live in humid
environments and undergo metamorphosis to reach the adult
state.
Characteristics of amphibians
 They are tetrapods: they have four leg-shaped limbs.
 Their skin is very thin and moist.
 Some have glands that produce poison.
 They undergo a process of changes called metamorphosis through which
they move from the tadpole state to the adult state.
 They are poikilotherms: they do not regulate their body temperature.
 Many of them hibernate during the winter.
 Almost all of them are carnivores.
 Have pulmonary breathing, supplemented with dermal breathing.
 They reproduce sexually with external fertilization.
 They are oviparous: they reproduce through eggs.
 They usually live in humid places and near water.
 They are classified into anura and urodela.

13. Amphibians
Amphibian life cycle

14. Amphibians
Characteristics of the anura
 They have a short body with a short neck.
 The hind legs are more developed.
 They don't have a tail.
 They have an extendable tongue to capture prey.
 They can produce sound.
 Frogs and toads belong to this group.
Characteristics of the urodela
 They have an elongated body with a differentiated neck.
 All legs are equally developed.
 They have a tail at the end of their body.
 They have developed teeth.
 They are unable to produce sound.
 The salamanders and the newts belong to this group.

15. Amphibians
Anurans

16. Amphibians
Urodelans

17. Reptiles
Reptiles are vertebrate animals that move by crawling, that is,
by dragging the bottom of their bodies.
Characteristics of reptiles
 They are tetrapods: they have four leg-shaped limbs, but some lack limbs.
 They have skin covered in scales or the body protected by a shell.
 They have a long tail ending in a point.
 They have pulmonary breathing.
 They are poikilotherms: they do not regulate their body temperature.
 Many of them hibernate during the winter.
 Almost all of them are carnivores.
 They reproduce sexually with internal fertilization.
 They are oviparous: they reproduce through eggs.
 They usually live in warm, dry places.
 They are classified as chelonians, ophidians, saurians and crocodilians.

18. Reptiles
Chelonians
 The turtles and the tortoises.
 They have a body protected by a shell.
 Sea turtles have legs in the form of fins.
 They have a corneal beak instead of teeth.

19. Reptiles
Ophidians
 They are the snakes, vipers, boas...
 They have cylindrical and elongated body.
 They don't have limbs.
 Some have venom glands.

20. Reptiles
Saurians
 They are the lizards, geckos, chameleons…
 Their body is elongated.
 They have four limbs, some with suction cups.
 They can detach their tail to escape from predators.

21. Reptiles
Crocodilians
 The crocodiles, alligators and caimans.
 They have a strong and robust body.
 Their limbs are adapted to the terrestrial environment.
 They have a large mouth with a lot of teeth.

22. Birds
Birds are terrestrial vertebrate animals that are able to fly.
Characteristics of birds
 They have four limbs: the two forelimbs transformed into wings and two
hindlimbs transformed into legs.
 They have a fusiform and aerodynamic body adapted to flight.
 Their body is covered in feathers, except on the legs.
 They have a very developed sense of sight and hearing.
 Their mouth has no teeth, with a beak whose shape depends on their diet.
 Their bones are thin, and many are hollow to reduce their weight.
 They have pulmonary breathing and have air sacs.
 They're homeotherms: they do regulate their body temperature.
 Some species migrate during the winter.
 They can be carnivorous or herbivorous.
 They reproduce sexually with internal fertilization.
 They are oviparous animals: they reproduce through eggs.

23. Birds
The feathers of birds

24. Birds
The legs of birds
The legs of birds are adapted to the environment in which they
live with the aim of being able to move more easily.

25. Birds
The beaks of birds
Each bird has a beak adapted to its diet, so it is possible to find
very different beak shapes within a group.

26. Birds

27. Mammals
Mammals are mainly terrestrial vertebrate animals, although
there are a few that are aquatic.
Characteristics of mammals
 They have a body covered in hair.
 The skin has numerous glands: sweat, sebaceous and breast glands.
 They have four limbs adapted to the environment they inhabit, and all
have the same anatomical structure.
 They have a highly developed nervous system and sense organs.
 Have pulmonary breathing.
 They're homeotherms: they regulate their body temperature.
 They may be carnivores, herbivores and omnivores.
 They reproduce sexually with internal fertilization.
 They are viviparous: young develop inside a womb.
 They are classified as placentals, marsupials and monotremes.

28. Mammals
All limbs have the same anatomical structure in mammals, even
though they are adapted to the environment in which the animal
lives.

29. Mammals
Mammal classification
Mammals can be classified according to the location and shape
of embryo development.
 Placentals: The embryo develops in the placenta, located in the womb.
This group comprises most mammals.
 Marsupials: The embryo ends its development in an external bag called
the marsupium. These are the kangaroos, koalas and possums.
 Monotremes: The embryo develops inside an egg. This is the case with
the platypus and echidna.
Marsupials MonotremesPlacentals

30. Mammals

31. Mammals
Characteristics of human beings
 We belong to the group of placental mammals and within this group we
belong to the order of primates.
 The forelimbs have been transformed into arms, which end in hands with
an opposable thumb used for handling objects.
 The hind limbs have been transformed into the legs, which are used for
movement. That's why we're bipedal.
 We have an extremely developed brain in terms of size and complexity,
which has allowed us to enhance our intelligence and develop a language
to communicate.
 Hair is concentrated only in some regions of our body.