AnimalsA SurveyChapters 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 theanimal, 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 Classes1. Jawless Fish (Agnatha)

Oldest class of vertebrateExample: 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 Classes5. 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 Classes7. 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 ClassesMammalian 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