Unit 7: Vertebrates                                                      1   2   3   4   5   6

1. Characteristics of animals

Organisms of Animal Kingdom are multicellular living beings, made up of eukaryotic animal cells and heterotrophs.

Almost all animals have organs and systems so that they can perform vital functions very efficiently.

- Nutrition: They have a digestive system, a respiratory system,

   a circulatory system and an excretory system. 

- Interaction: They have a nervous system, an endocrine system

   and a tegument.

- Reproduction: They have a reproductory system.

Traditionally the Animal Kingdom is divided into two groups:

        - Vertebrates. They are the animals with internal skeleton.

    - Invertebrates. They are the animals without internal skeleton.

This classification is not scientific because invertebrates do not have evolutionary relationship among them. In contrast Vertebrates are related, that is they have a common ancestor. Vertebrates are the most evolved group of the Phylum Chordates.

1.1. Characteristics of Vertebrates

All vertebrates have in common the same organisation body plan. They share the following characteristics:

- They have internal skeleton (endoskeleton) with backbone (spinal column)

- Its body is divided into a head, a trunk and most have a tail.

- They have four limbs (legs, wings or fins).

- They have bilateral symmetry.

- They have a complete digestive tube (with mouth and anus) with glands.

- They have a close circulatory system (that is blood always flows

   within the blood vessels)

- They have a well-developed nervous system (brain, spinal cord,

   nerves and sense organs).

- They have sexual reproduction and sexes are separated (male and female)

They are divided into five groups: fish, amphibians, reptiles, birds and mammals.

1. 1. Answer the questions:

1.2. Listen and indicate if the sentences about vertebrates are true or false: