Animal Characteristics and Animal Diversity Mr. Chapman Biology 20
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? • Animals are multicelllular. • All animals have eukaryotic cells. • Animals are heterotrophs (they eat other organisms) They lack chloroplasts to make their own food. • Animal cells are supported by collagen. • 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.
Animals and Fungi are both Heterotrophic Eukaryotes The cells of fungi do not perform some of the specialized functions that animal cells do, and as a result they are classified differently. It is likely that fungi and animals evolved separately from each other. Could this cat eat YOU?
Animal Cells Don’t Have Cell Walls? Whatever will we do for support? • Unlike plants and fungi, animals do NOT have cell walls. Because of this, animals are the only multicellular organisms without support for their cells. • Collagen is a three-stranded protein that is unique to animals. Collagen proteins form rope-like fibers that are both strong and flexible.
Collagen Collagen can be found in all sorts of animal body parts, such as bone, skin, ligaments, fingernails, and hair. These fibers form an extracellular network that many animal cells use for support. Unlike a cell wall, the collagen network does not glue cells in place, so it is posisble for cells to move within the animal’s body.
I don’t need no man... Come to think of it, no men even EXIST.
Oh yes, they are diverse... Animal Diversity Mr. Cherewyk’s last trip to the doctor... Doesn’t that bird look like him? Do you see it???
Vertebrates and Invertebrates • A vertebrateis 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. • Invertebratesare 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: • Sponges and cnidaria • Mollusks • Arthropods • Nematoda Snails and octopi are in the same phylum... Mollusks. What’s the deal?
Many Criteria Indeed... Animals Are Grouped Using A Variety of Criteria.. Body Plan Symmetry Tissue Layers Developmental Patterns
Body Plan Symmetry • Symmetry refers to how similar an object is across a central axis. • If you cut a square in half with one line, it is the same on both sides. This makes the object symmetrical. • An object is asymmetrical if the two sides are not equal. • Most animals have one of two forms of symmetry.
Bilateral animals have distinct heads and tails, which are called the anterior (head) and posterior (tail) ends. They also have distinct backs and bellies, which are called the dorsal (back) and ventral (belly) surfaces. These terms will be important for you to remember!
Developmental Patterns • Animals are separated into two major divisions: protostomes and deuterostomes. • The major difference between protostomes and deuterostomes is which end of the digestive system develops first: the anus or the mouth. • What do you think humans develop first, an anus or a mouth?
Protostomes vs. Deuterostomes • In protostomes, the mouth is formed first and the anus is formed second. • In deuterostomes, the anus is formed first and the mouth is formed second. • Humans are... Deuterostomes! Yep, before you had a mouth, you had an anus! http://www.classzone.com/cz/books/bio_07/get_chapter_group.htm?cin=8&rg=animated_biology&at=animated_biology&var=animated_biology
ProtostomeDeuterostome Turn to Page 703!