Unit 9--Vertebrates

Chapter 30-32Nonvertebrate Chordates, Fishes & Amphibians

Reptiles & BirdsMammals

Phylum Chordata Characteristics:

At some time in their life, all chordates have:

• A dorsal nerve cord = gives rise to spinal cord

• A notochord = flexible supporting rod that gives rise to vertebrae

• Postanal Tail that extends beyond the anus

• Pharyngeal slits = gives rise to gills

• Most in subphylum Vertebrata

Dorsal, hollow nerve cord

• Located on the back (dorsal) part of the body

• Nerves branch from this to all parts of the animal’s body

Notochord

• Located beneath the nerve cord

• Long supporting rod

• For most vertebrates, the notochord is present only in the embryo stage.

• In some, vertebrae (backbone) replaces the notochord.

Embryonic Ciona with visible notochord

Doe Joint Genome Institute

Notochord formation

Pharyngeal pouches

• Paired structures in the throat (pharynx) region

• For fishes, slits develop that connect the pouches to the outside of the body, becoming gills.

Postanal tail

• Extends beyond the anus

• Bone and muscle within

• Facilitates in swimming

human embryo with tailbud

Section 30-1

Nonvertebratechordates

FishesAmphibians

ReptilesBirds

Mammals

Invertebrate ancestor

Chordate Cladogram

Subphylum:

Urochordata = Tunicate (sea squirt) only larva has all characteristics

Subphylum:Cephalochordata = Lancelets the only adult to retain all characteristics

Lancelet characteristics

•Small, fishlike animals•Live on ocean floor•An adult lancelet has a mouth that connects to the pharynx, which secretes a sticky mucus to trap

food.•Closed circulatory system but no true

heart

Subphylum Vertebrata:

• Class Agnatha = the jawless fishes• Ex: sea lampreys & hagfish

•

Lamprey are external parasites, 1 while hagfish are “bottom feeders.”

Class Chondrichthyes

• Cartilaginous fishes• Ex: Sharks, rays & skates

Sharks have several 6-10 rows of replaceable teeth and toothlike placoid scales

Shark bite

Note the size of the shark tooth as compared the size of an average adult hand.

Class Osteichthyes

• Bony fish (with jaws & paired fins)• Ex: sea horse, lion fish, perch, trout, etc

Fish anatomy:

• Overlapping scales for protection

• Gills with countercurrent exchange

• Operculum = gill cover

• Flattened bodies to increase speed

Respiration

• Most fishes use gills.• Gills are made up of

feathery, threadlike structures called filaments.

• The operculum, a bony covering, protects the gill slit(s).

Feeding

• Types of feeders– Herbivores: vegetative matter only– Carnivores: meat only– Parasites: feeds on other animals– Filter feeders: sifts matter out of water– Detritus feeders: feeds on dead or decaying

matter

• Food enters the mouth, stomach, pyloric ceca (digestive enzymes), intestines, and out the anus.

Movement

• Alternating muscles on either side of the spine allows for S-shaped curve that pushes water

• Fins for directional movement

• Swim bladder: helps to adjust for buoyancy

swim bladder

Response

• Well-developed brain and chemoreceptors to detect taste and smells

• Lateral line system that detect vibration and current changes

Class Amphibia

• “double life”• Ex: frogs toads,

salamanders, newts

Amphibian characteristics

• Vertebrate

• Lives in water as a larva but on land as an adult

• May returns to water to reproduce

• Uses gills as larva but lungs as an adult

• Moist skin with mucus glands

• No scales or claws

Amphibian Anatomy

• Inefficient 3 chambered heart• “Skin breathing” to help inefficient lungs• Moist skin• Webbed feet,

no claws• Metamorphosis

Reptilian characteristics

•Dry, scaly skin•Lungs•Internal fertilization•Terrestrial eggs with several membranes•Double-loop circulatory system•Strong limbs•Ectothermic•Vertebrate•Diverse habitats

Reptile anatomy

• Ectothermic (cold-blooded) = body temp changes with environment

• Dry, waterproof skin with claws

• Partially divided 3 chambered heart

Class Reptilia

• Ex: snakes, lizards, turtles, alligators

• Tuatara = only member is its order

Amniote Egg allows reptiles to lay eggs on land

CHORION

Rattlesnakes are “Pit vipers” with a heat sensitive organ that detects warm-blooded prey

Class Aves (the birds)

• Endothermic (warm-blooded) body temp constant

• 4 chambered heart

• Well-developed lungs

Bird characteristics

• Reptile-like • Aerodynamic feathers• Two legs covered with

scales• Front limbs modified into

wings• Highly efficient

metabolism• Strong, lightweight bones

“Volta” the bald eagle – Alaskan Bird Rehabilitation Center

Levy

Reptiles vs. Birds

• Feathers are produced by tissues similar to those that produce reptile scales.

• Birds have scales on their feet.• Birds lay eggs like reptiles. • The soft anatomy

(musculature, brain, heart, and other organs) all are fairly similar.

Information from UC Berkeley, Museum of Paleontology

Bird Anatomy

• Feathers for insulation, protection & coloration, assist in flight

• Hollow bones for lightweight

Birds reduce weight for flight whenever possible, i.e. air sacs attached to lungs & one ovary in females.

Compare: Heart chambers Skin coverings Respiration types Cold vs Warm-blooded Reproduction types

Mammal characteristics

• Hair

• Mammary glands

• Require oxygen

• Four chambered hearts

• Endothermic

Sea World, whale calf nursing

Class Mammalia

• Hair (to insulate, camouflage, etc)

• Mammary glands (to nurse young)

• Viviparous (bear live young)

• Specialized teeth (determines lifestyle)

• Nails, claws or hooves

Regulating Body Temperature

• Endotherm: animal that can generate body heat internally through metabolic processes

• Body hair: insulates

• Subcutaneous fat: layer beneath the skin to help conserve heat

• Sweat glands: evaporative cooling

• Regulating body temperature = homeostasis

Hair

• Only mammals have hair. Whales and dolphins (marine mammals) have sensitive bristles on their snouts.

• Functions: insulation, camouflage, sensory input (environmental awareness)

Feeding

• Because of metabolic rate, mammals must eat 10x the amount of food as reptiles.

• Herbivores: consume only vegetative matter• Carnivores: consume only meat• Omnivores: consume meat and vegetables• Filter feeders: sift out plankton and small fish

from water

• Name an example of each type of animal feeder.

Section 32-1

CARNIVORE HERBIVORE

Molars crush and grind food. The ridged shape of the wolf’s molars and premolarsallows them to interlock during chewing, like the blades of scissors. The broad,flattened molars and premolars of horses are adapted for grinding tough plants.

Chisel-like incisors are used forcutting, gnawing, and grooming.

Canines are pointed teeth. Carnivoresuse them for piercing, gripping, and tearing.In herbivores, they are reduced or absent.

Jaw jointJawjoint

WolfHorse

Specialized teeth

Figure 32–4 The Jaws and Teeth of Mammals (p. 823)

Respiration

• All mammals, even marine, have lungs to breathe in oxygen and exhale carbon dioxide.

• The diaphragm muscle lowers to help expand the chest cavity for greater volume.

Excretion

• Kidneys help mammals maintain homeostasis (water and salt balance).

Response

• Mammals have the most highly developed brains.

• Diurnal animals have the best developed color vision since these animals are awake during daylight.

• Mammals also have highly developed sense of smell and hearing.

Chemical Controls

• Endocrine glands: produce and secrete hormones that affect other organs and tissues

• Hormones can regulate mammal behavior and vital functions such as maintaining blood sugar or calcium levels.

Fighting Disease

• Immune systems help mammals ward off pathogens, disease-causing microorganisms, that may invade the body.

Reproduction

• All mammals…– Internal fertilization: male deposits sperm

inside the female reproductive tract– requires mother’s milk for nourishment when

young– display maternal care

Classification by reproduction:

• Monotremes (egg-laying)

• Ex: platypus& echidna

• Marsupials (pouched)

• Ex: koala, kangaroo &

opossum

Reproduction

• Different ways that fetal mammals develop– Monotremes: lay eggs

• Platypus, spiny anteaters (echidnas)

– Marsupials: live birth of young that then finish development in an external pouch

• Kangaroo, koala, wombat

– Placental: nutrients, oxygen, carbon dioxide, and wastes are exchanged between embryo and mother through the placenta structure

• Primates, dogs, cats, pigs, horses, etc.

Placental Mammals

Include 95% of all Mammals

Includes 15+ orders

Rodentia (gnawing)

largest, most successful orderlargest, most successful order

Insectivores = moles…

include smallest mammal, the shrewinclude smallest mammal, the shrew

Edentates (toothless) most primitivemost primitive

Chiroptera = bats

Bats are only mammals capable of “true” flight

Carnivora special traits for huntingspecial traits for hunting

Aquatic mammals are capable of holding their breath for several hours

Cetaceans = whales, dolphins

Hoofed mammalsAre grouped by Number of toes

(even or odd)

They tend to be Large grazers

___dactyla

Trunk-nosed mammals have only 2 species, African and Indian

Probosiceans = elephants

haveopposable thumbs & superior intelligence

They are theonly mammal to make use of tools

Primates