Animals A Survey Chapters 23-27

General Animal Characteristics 1 million + species of animals have been discovered 1. All animals are multicellular 2. All animals are heterotrophs (consumers)

General Animal Characteristics, cont. 3. Animal cells lack the rigid cell walls that are found in plants & fungi 4. Animal body parts such as skin, bone, ligaments, and fingernails contain collagen (a protein) 5. Animals are diploid and usually reproduce sexually

General Animal Characteristics, cont. 6. Hox Genes ▫Most animals have a set of nucleotides call Hox genes ▫Hox genes determine how cells will develop into specific organs and tissues

Animal Diversity Invertebrate ▫Animal without a backbone Vertebrate ▫Animal with an internal segmented backbone

Body Plan Symmetry Bilateral symmetry ▫A plane can cut through the animal, splitting an animal into two mirror-image sides Radial symmetry ▫Body parts are arranged circularly around a central axis

Invertebrates 6 Basic Groups 1. Sponges  Most primitive animals on Earth  Cannot move 2. Cnidarians  Can move  Examples include jellyfish and corals 3. Worms: Flat Worms, Annelids, and Round Worms  Bilateral symmetrical  Annelids have segmented bodies  An earthworm is an annelid

Invertebrates, pt 2 6 Basic Groups 4. Mollusks  Bilaterally symmetrical  Complete digestive track  Include snails, clams, and octopuses 5. Echinoderms  Radially symmetrical  Slow moving  Include sea stars, sand dollars, and sea urchins 6. Arthropods  Most diverse group of all animals  Bilateral symmetry  Have exoskeletons made of Chitin  Have jointed appendages  Among arthropods are insects, crustaceans, myriapods, and arachnids

Vertebrates The phylum Chordata contains all vertebrates (and some invertebrates) 7 Classes of Vertebrates Vertebrates have an endoskeleton ▫Internal skeleton built of bone & cartilage

Vertebrate Classes 1.Jawless Fish (Agnatha) Oldest class of vertebrate Example: lamprey 2.Cartilaginous Fish (Chondrichthyes)  Skeletons made of cartilage  Examples: sharks and rays 3.Bony Fish (Osteichthyes)  Skeletons made of bone  Most diverse class of vertebrates 4.Amphibia  First vertebrates to live on both water & land  Reproduce in water or moist land  Include salamanders and frogs

Vertebrate Classes 5. Reptilia  Live on land  Eggs develop on land  Snakes, lizards, crocodiles, alligators, and turtles  Amniotes (animals that develop in a fluid-filled, nutrient rich sac either within an egg or their mother)  Ectotherms body temp is determined by their environment 6. Aves (Birds)  Feathers are distinguishing feature  Most fly  Endotherms (use metabolism to keep their tissues warm)  Amniotes

Vertebrate Classes 7. Mammal Characteristics  Endothermic  Amniotes  Hair  Mammary glands  Mammals take care of their young after birth  Mammary glands produce milk, rich in nutrients for the young  Middle ear  Allow the mammal to hear  Jaw for chewing  Mammals break up their food as soon as it enter the mouth

Vertebrate Classes Mammalian Groups (3) 1.Monotremes ▫Mammals that lay eggs ▫Example: Platypus 2.Marsupials ▫Give birth to immature young ▫Young grow to maturity inside a pouch ▫Examples: kangaroos, koalas, opossums 3.Eutherians ▫Give birth to live young that have completed fetal development ▫Longest gestation ▫Examples: whales, bats, elephants, tigers