Introduction to the Animal Kingdom

Vocabulary list

lack - to not have something, or not have enough of something: An animal cell lacks cell walls.

share - to have the same interest/opinion, etc as someone else: All plants share certain characteristics.

enable - to make someone able to do something, or to make something possible: Many body functions enable animals to maintain homeostasis.

vertebral column / backbone - a ​spine, the line of bones down the centre of animal’s back

vertebrate - an ​animal that has a ​spine /invertebrate - an ​animal with no ​spine: Invertebrates, such as ​worms, are the ​main ​diet of these ​water ​birds.

bilateral symmetry - the fact of the two halves of something on either side of a particular line being exactly the same / radial symmetry - the condition of having similar parts regularly arranged around a central axis

homeostasis - internal conditions remain stable and relatively constant.

body cavity - any fluid-filled space in a multicellular organism other than those of vessels.

All members of kingdom Animalia share certain characteristics. Animals are multicellular, eukaryotic heterotrophs whose cells lack cell walls. The bodies of most animals contain tissues. Over 95 percent of all animal species are often grouped in a single, informal category: invertebrates. Invertebrates are animals that have no backbone, or vertebral column. The other 5 percent of animals are called vertebrates, because they have a backbone.

Animals carry out the following essential functions: feeding, respiration, circulation, excretion, response, movement, and reproduction. The study of the functions of organisms is called physiology. The structure, or anatomy, of an animal’s body enables it to carry out physiological functions. Many body functions help animals maintain homeostasis. Homeostasis is often maintained by internal feedback mechanisms. Most of these mechanisms involve feedback inhibition, in which the product or result of a process stops or limits the process. Complex animals tend to have high levels of cell specialization and internal body organization, bilateral symmetry, a front end or head with sense organs, and a body cavity.

Answer the questions:

What is an animal?

What animals can be called invertebrates?

What essential physiological functions do animals carry out?

 What type of symmetry do vertebrates have?