1 Compare and Contrast How do vertebrates differ from other chordates

2 Review Describe the seven essential functions performed by all animals

Explain Why must waste products produced by metabolic processes be eliminated from an animal’s body

3 Classify A classmate is looking at a unicellular organism under a microscope and asks you if it is an animal- what do you answer and why

CH 25 INTRODUCTION TO ANIMALS25.1 What is an Animal

Characteristics of Animals

Heterotrophs Obtain energy by eating other organisms

Multicellular Bodies are composed of many cells

Eukaryotic Contain a nucleus and membrane-bound organelles

Lack cell walls.

Types of Animals

Invertebrates Chordates.

Invertebrates

Include all animals that lack a backbone, or vertebral column

More than 95 percent of animal species are informally called invertebrates

From dust mites to giant squid.

Chordates

Exhibit at some stage of life: Dorsal, hollow nerve cord Notochord Tail that extends beyond the anus Pharyngeal pouches.

Chordates

Hollow nerve cord runs along the dorsal (back) part of the body

Nerves branch from this cord at intervals.

Chordates

Notochord is a long supporting rod that runs through the body just below the nerve cord

Most chordates only have a notochord as embryos.

Chordates

All chordates have a tail that extends beyond the anus at some point in their lives.

Chordates

Pharyngeal pouches are paired structures in the throat region (pharynx)

Slits may develop to connect to outside of body for gas exchange (gills).

Most chordates develop a backbone, or vertebral column, constructed of bones called vertebrae

Vertebrates Chordates with backbones Fishes, amphibians, reptiles, birds, and mammals.

Animal Survival

Maintaining Homeostasis

Feedback inhibition or negative feedback System in which the product or result of a process

limits the process itself If you get too cold, you shiver, using muscle activity to

generate heat Thermostat in house.

Gathering and Responding to Information

Nervous system gathers information using receptor cells that respond to sound, light, chemicals, and other stimuli

Other nerve cells collect and process that information and determine how to respond.

Often respond to processed information by moving Muscle tissue contracts when stimulated by the

nervous system Muscles work together with some kind of a

skeleton.

Some invertebrates have only a loose network of nerve cells, with no real center

Other invertebrates and most chordates have large numbers of nerve cells concentrated into a brain.

Obtaining and Distributing Oxygen and Nutrients

All animals must breathe to obtain oxygen May use gills, lungs, or air passages.

All animals must eat to obtain nutrients Most animals have a digestive system that acquires

food and breaks it down into forms cells can use.

Animals must transport them to cells throughout their bodies by using some kind of circulatory system.

Collecting and Eliminating CO2 and Other Wastes

Animals’ metabolic processes generate carbon dioxide and other waste products, some of which contain nitrogen in the form of ammonia

Many animals eliminate carbon dioxide by using their respiratory systems.

Most complex animals have a specialized organ system for concentrating, processing, and eliminating other wastes, such as ammonia.

Circulatory system must collect wastes from cells throughout the body and then deliver them to the respiratory or excretory system.

Reproducing

Most animals reproduce sexually by producing haploid gametes

Many invertebrates and a few vertebrates can also reproduce asexually.