Unit 4: Animal Systems An Introduction to Animals Mr. Chapman Biology 30

Animals are Physically Diverse Animals are the most physically diverse kingdom of organisms. Animals can be found nearly everywhere on earth, including some places in which plants and fungi do not live. Some have the most boring lives that you could ever imagine.

A Sponge’s Life Sucks... Sponges have long been considered the most primitive animals on earth. They spend their entire adult lives fixed to a single spot, filtering water to collect microscopic particles of food. To learn more about these thrillers, see section 23.3 of the textbook. We will not cover them in class except to say this: 570 million year old sponge fossils have been found, making them among the most ancient animals.

All Animals Share a Set of Characteristics... Can we come up with a list of common characteristics that all animals share? 1. Animals are multicelllular. 2. All animals have eukaryotic cells. 3. Animals are heterotrophs (they eat other organisms) They lack chloroplasts to make their own food. 4. Animal cells are supported by collagen. 5. Animals are diploid.

Animals Must Eat Anything that an animal uses for cellular respiration must come from an outside source. This includes sugars, proteins, and fats. Single-celled protists also eat other organisms, but because even the simplest animal is composed of many cells, it can eat bigger things than a protist can.

Vertebrates and Invertebrates A vertebrate is an animal with an internal segmented backbone. You are a vertebrate, and so are other animals. However, we only make up a total of 5% of all the known animal species. Invertebrates are animals without backbones. They make up the vast majority of animals on the planet.

An Outdated System of Classification Previously, scientists used to classify animals initially based on their status as vertebrates or invertebrates. As biologists learned more and more about animals, it became clear that invertebrates were so diverse from each other that they should not necessarily be categorized together anymore.

Animal Phyla Because of this, scientists now use shared characters to divide animals into more than 30 major groups. Each group, or phylum, of animals is defined by structural and functional characteristics that are different from every other animal group. Each animal phylum has a unique body plan and represents a different way that a multicellular animal is put together.

Invertebrates The invertebrates include many different phyla, such as the following: 1. Sponges and cnidaria 2. Mollusks 3. Arthropods 4. Nematoda Snails and octopi are in the same phylum... Mollusks. What’s the deal?

Percentage of Invertebrate Species

ANIMALS ARE GROUPED USING A VARIETY OF CRITERIA.. Many Criteria Indeed... 1.Body Plan Symmetry 2.Tissue Layers 3.Developmental Patterns