Phylum Chordata Ch.17, 18, 19, 20, 21, 22. Introduction to Phylum Chordata: Chapter 17.

Phylum ChordataCh.17, 18, 19, 20, 21, 22

Introduction to Phylum Chordata:

Chapter 17

General Characteristics of Phylum Chordata

~45,000 speciesBilaterally symmetrical, deuterostome

animalsNotochord (Greek: noton=back,

chorda=cord)Complete digestive tractPharyngeal slitsPostanal tailAquatic and terrestrial animalsVentral, contractile blood vessel (heart)

Where we are going…..

Subphylum Vertebrata◦Class Cephalapidomorphi (Lampreys)◦Class Chondrichthyes (Rays, Sharks, Skates)◦Class Osteichthyes (Bony Fish)◦Class Amphibia (Frogs, Toads, Salamanders)◦Class Reptilia (Snakes, Lizards, Alligators)◦Class Aves (Birds)◦Class Mammalia (Mammals)

The FishChapter 18

Class Cephalaspidomorphi

LampreysFishlike; jawed; paired appendages and

cartilaginous skeleton; sucking mouth with teeth and rasping tongue

Seven pairs of pharyngeal slitsInhabitants of marine and freshwater

environments in temperate regionsGenerally prey on other fish:

◦ Mouth of adult is suckerlike and surrounded by lips that have sensory and attachment functions

◦ Numerous teeth line the mouth and cover a movable tonguelike structure

◦ The lamprey attaches to its prey with its lips and teeth and uses its tongue to rasp away scales

◦ Lampreys have salivary glands with anticoagulant (like leech) secretions and feed mainly on the blood of their prey!

Class Chondrichthyes

Sharks, Rays, and SkatesFishlike, jawed, paired

appendages and cartilaginous skeleton

Tail fin with large upper lobeLack opercula (gill cover), swim

bladder (helps in buoyancy-use liver instead), and lungs

Carnivores or scavengersMostly Marine~820 species

Class Chondrichthyes

Tough skin with placoid scales (see pg. 282). Scales project posteriorly and give the skin a touch texture.

Dried shark skin has been used for sandpaper!

Shark teeth are actually modified placoid scales!

The row of teeth on the outer edge of the jaw is backed up by rows of teeth…as the outer teeth wear and become useless, newer teeth move into position from the next row.

In young sharks, this replacement is rapid, happening every 7 or 8 days!

Class Chondrichthyes

Sharks range in size from less than 1 meter to greater than 10 meters!

The largest living shark is the whale shark that is not even a predator but a filter feeder!

The fiercest and most feared sharks are the great white sharks.

Extinct species may have reached lengths of 15 meters or more.

Class Chondrichthyes

Skates and Rays◦Specialized for life on the ocean floor,

generally inhabiting shallow waters, where they use their teeth to feed on invertebrates

◦Modified to live on ocean floor by the lateral expansion of the pectoral fins into winglike appendages

◦Often use colors on dorsal side as camouflage

◦The sting ray has a tail modified into a defensive lash (the barb)

◦Also, in this group are the electric rays and manta rays.

Class Osteichthyes

Bony Fish◦ Have at least some bone in their skeleton/scales

Larges vertebrate class ~24,000 speciesHave lungs or swim bladder

◦ Gas-filled sacs along the dorsal wall of the body cavity that regulates buoyancy

Have operculum◦ Gill cover

Locomotion: fins and body wall, muscles run in a zig zag pattern and each contraction can be powerful

Most modern fish are predators and spend much time searching for food (prey varies greatly)

Have a central nervous system with a brain and spinal cord

Bony Fish Circulation & Gas Exchange

Circulation:◦Closed circulatory system in which a heart

pumps blood with red blood cells through a series of arteries, capillaries, and veins

◦In most fish, blood passes through the heart once with every circuit around the body

Gas Exchange:◦To maintain oxygen levels underwater, fish

must pass large quantities of water across gill surfaces and extract the small amounts of oxygen present in the water (fish use different methods of doing this)

Electroreception & Electric Fish

Electroreception: ◦The detection of electrical fields that a fish or other

organisms in the environments generate.◦All organisms produce weak electrical fields from the

activities of nerves and muscles◦Example: Spiny dogfish sharks locate prey using

electroreception. This shark can find and eat a flounder that is buried in sand, but cannot find a dead flounder

Electric fish:◦Some fish are not only capable of electroreception, but

can also generate electrical currents!◦Best known-Electric Eel◦Electric Eel is found in rivers in South America◦The organs for producing electrical current are in the

trunk of the electric eel and can deliver shocks in excess of 500 volts!

Class AmphibiaChapter 19

Class Amphibia

Skin with mucoid secretionsPossess lungs/gillsMoist skin serves as

respiratory organLack scales, feathers, and hairLarvae usually aquatic and

undergo metamorphosis to become adult

Two atrial chambers in the heart

Occur on all continents except Antarctica, but they are absent from many oceanic islands

We will focus on two Orders: Caudata & Anura

Order Caudata

Salamanders and Newts Possess a tail throughout life Both pairs of legs, when present, are unspecialized ~115 of the 350 species live in North America! Most terrestrial salamanders live in moist forest-floor litter and

have aquatic larvae. Newts live most of their life in water and usually retain their

caudal fin. Salamanders range in length from only a few centimeters to 1.5

meters. The largest North American salamander is the hellbender,

which reaches lengths of about 65cm. Most salamanders have internal fertilization, but not copulation. Larvae are similar to adults, but smaller. The aquatic larval

stage usually metamorphoses into a terrestrial adult

Order Anura

Frogs and Toads~3,500 speciesMost live in moist environments, but some even

occur in very dry desertsAdults lack tailsHindlimbs are long and muscular and end in webbed

feetFertilization is almost always external, and eggs and

larvae are typically aquatic, larval stages, called tadpoles, have well-developed tails

“Frog” and “Toad” really aren’t that different scientifically. Toad usually means anurans with dry and warty skin that are more terrestrial than other members in the order-which is true in many families! True toads belong to the family Bufonidae.

Class Amphibia External Structure

Amphibian skin lacks a covering of scales, feathers, or hair, but it is highly glandular and its secretions aid in protection.

These glands keep the skin moist to prevent drying

They also produce toxic chemicals that discourage potential predators.

Chromatophores are specialized cells of the skin that are responsible for skin color and color changes-cryptic coloration and mimicry are common in amphibians

Class Amphibia Digestion

Most adults are carnivores that feed on a variety of invertebrates, although some anurans are more diverse.

Example: bullfrogs will prey on small mammals, birds, and other amphibians!

The main factors that determine what amphibians will eat are prey size and availability.

Most amphibians locate their prey by site and simply wait for prey to pass by.

Also, amphibians have the first true tongue and use it as a feeding mechanism!

Amphibian Gas Exchange

Most people have experienced that amphibians have moist skin, and amphibian skin also has many capillary beds.

These 2 factors permit the skin to function as a respiratory organ.

Gas exchange across skin is called Cutaneous Respiration and can occur in water or on land.

Exchanges of oxygen and carbon dioxide require most surfaces and exposure or respiratory surfaces to air may result in rapid water loss!

Most amphibians have lungs, but larvae may use gills in the beginning that will seal up and become lungs later in life.

Amphibian Temperature Regulation

Amphibians are ectothermic, meaning that they depend on external heat sources to maintain body temperature.

Many amphibians are nocturnal and remain in cooler burrows or under moist leaf litter during hot times.

Amphibians may warm themselves by basking in the sun or on warm surfaces.

Basking after a meal is common because increased body temp increases the rate of metabolism.

Amphibian Vocalization

Sound production is primarily a reproductive function of male anurans (frogs/toads).◦Advertisement calls attract females to breeding

areas and announce to other males that a given territory is occupied.

◦Advertisement calls are species specific.◦Females respond by making reciprocation calls to

indicate receptiveness.◦The use of sound to attract mates is useful in

organisms that occupy widely dispersed habitats and must come together for breeding.

◦Also, because many frogs often come to the same pond for breeding, finding a mate of the proper species could be chaotic, but vocalizations help in this manner!

Amphibian Vocalization

Frogs and Toads also use vocalization as distress calls.◦Distress calls are not associated with reproduction

and both a male or a female can produce these calls

◦Distress calls are in response to pain or being seized by a predator and may be loud enough to cause a predator to release the frog or toad.

◦The distress call of the South American jungle frog is a loud scream similar to the call of a cat in distress!

Wildlife Alert: Red Hills Salamander pg. 309Answer the Questions Above

1. Record the Vital Statistics in your Notes.2. How big does this salamander get?3. Is there an aquatic larval stage?4. Are there Red Hills Salamanders in the

Shoals?5. What are the primary threats to these

salamanders?6. Who owns 60% of the salamanders’ habitat

that is destroying it by clear cutting trees?

Class ReptiliaChapter 20

Class Reptilia Characteristics

Dry skin with epidermal scalesRespiration via LungsInternal FertilizationFirst Vertebrates to have Amniotic Eggs

◦Have extraembryonic membranes that protect the embryo, cushion the embryo, supplies food to embryo, promote gas transfer, and store waste materials.

◦These eggs are made for land developmentTerrestrial embryonic developmentWe will focus on three Orders:

◦Testudines (Turtles)◦Squamata (Snakes, Lizards, Worm Lizards)◦Crocodilia (Crocodiles, Alligators)

Order Testudines (Turtles)

~225 species Teeth absent in adults and replaced by a beak Short broad body Bony Shell Present-in some turtles, shell has hinges (box

turtle) which allows openings to close when turtle withdraws into shell!

Have long life spans, most live 14 or more years, and large tortoises, like those of the Galapagos Islands, may live in excess of 100 years! (Tortoises are completely terrestrial)

All turtles are oviparous: females make nests for eggs in soil, then lay the eggs, then cover the eggs with soil. Development takes from four weeks to one year, and the parent does not attend to the eggs during this time. The young are independent when they hatch!

Slow growth rates and long juvenile periods make turtles vulnerable to extinction in the face of high mortality rates, but luckily, in recent years, turtle conservation programs have been enacted.

Order Squamata

The Order Squamata is divided into three suborders:

◦Suborder Sauria-The Lizards◦Suborder Serpentes-The Snakes◦Suborder Amphisbaenia-Worm Lizards

Lizards

~3,300 species Usually have 2 pairs of legs Vary in length from only a few centimeters to as large as 3

meters! Many lizards live on surface areas but retreat under rocks or

logs when necessary, others are burrowers or tree dwellers Example Species:

◦ Geckos Commonly found in subtropical areas, nocturnal, capable of clicking

vocalizations, large eyes with unique pupils are adapted for night vision, adhesive disks on their digits allows them to cling to trees and walls.

◦ Chameleons Use a long, sticky tongue to capture insects, well known for their ability

to change color in response to illumination, temperature, or their behavioral state

◦ Gila Monster & Komodo Dragon The only venomous lizards, heavy-bodied lizards are native to

southwestern North America. Lizard bites are seldom fatal to humans!

Snakes

~2,300 species The vast majority of snakes are not dangerous to humans, but

about 300 species are venomous Worldwide:30,000-40,000 people die from snake bites/year.

United States: fewer than 100/year. Snakes are elongated and lack limbs The skeleton may contain more than 200 vertebrae and pairs

of ribs! Snakes possess skull adaptations that facilitate swallowing

large prey Elongation in snakes has resulted in the reduction or loss of

the left lung and displacement of the gall bladder, the right kidney, and often, the gonads.

Most snakes are oviparous, although a few, such as the New World Boas and garter snakes, give birth to live young!

Order Crocodilia

Only 21 species! Living crocodiles include the alligators, crocodiles, gavials,

and caimans. Crocodiles have not changed much over their 170 million

year history Snout is elongated and often used to capture food by a side

ways sweep of the head. Nostrils are at the tip of the snout, so the animal can breath

while mostly submerged. The muscular and long tail is used for swimming, offensive

and defensive maneuvers, and attacking prey. Teeth are used only for seizing prey. Food is swallowed whole, but if a prey is too large, the croc

will tear it apart by holding onto a limb and rotating their bodies wildly until the prey is dismembered.

Crocodilians are oviparous and display parental care of hatchlings that is similar to birds.

Alligator or Crocodile??

Wildlife Alert:Kemp’s Ridley Sea Turtle

Page 324 Answer the Questions Above in your Notes

1. Copy the Vital Statistics2. How big do adult Kemp’s Ridley Sea Turtles

get?3. Where are adults primarily found nesting?4. What do they feed on?5. When does nesting occur?6. When was Kemp’s Ridley Sea Turtle placed

on the federal endangered species list?7. What is the recovery plan’s goal number of

females nesting in a season?

Class Aves (Birds)Chapter 21

Bird Characteristics

Adaptations for flight A high metabolic rateEndothermic (heat is derived from own body

system)Lack teethSimilarities between birds and reptiles are so

striking, the bird is often referred to as “glorified reptiles”

~9,000 species of living birds divided into about 27 orders

Orders are divided according to behaviors, songs, anatomical features, and ecological niches

Feathers

Covering of feathers on a bird is called plumage.Feathers have 2 primary functions essential for

flight: form the flight surfaces that provide lift and steering and they prevent excessive heat loss.

Feathers also have roles in courtship, incubation, and waterproofing.

Birds preen feathers to keep them smooth, clean, and in place.

Mature feathers receive constant wear, so birds periodically shed and replace feathers in a process called molting.

Birds have 3 types of feathers:◦ Contour-cover body, wings and tail◦ Down-insulating feathers◦ Filoplum-(pinfeathers)have sensory functions

Skeleton

Bones of most birds are lightweight, yet strong

Some bones have large air spaces and internal reinforcement of bones for strength

Birds have a reduced number of skull bones and a bill that replaces teeth.

The demand for lightweight bones is countered in some birds with other requirements◦ Example: Some aquatic birds have dense

bones (heavier), which help reduce buoyancy during diving.

Furcula (wishbone):◦ Paired clavicles that fuse together to serve

as an additional site for the attachment of flight muscles.

Flight

Wings of birds are adapted for different kinds of flight, but no matter if a bird glides, soars, or has rapid flapping flight, the mechanics of staying aloft are similar:

◦ Bird wings form an airfoil◦ Anterior margin of wing is thicker than posterior margin◦ Upper surface of the wing is slightly convex (outward), and

the lower is slightly concave (inward)◦ Air passing over the wing travels farther and faster than air

passing under the wing, decreasing air pressure on the upper surface of the wing and creating LIFT!

The tail of a bird serves a variety of balancing, steering, and braking functions during flight.

Nutrition and Digestion

Most birds have huge appetites to support their high metabolic rate that makes endothermy and flight possible

Bird Bills and Tongues are modified for a variety of feeding habits and food sources.

Reproduction & Development

All birds are oviparous (lay eggs that develop outside of the body of the female)

Many birds establish a territory prior to mating to allow that species to mate without interference.

Mating may follow the attraction of a mate to a territory:◦ Male woodpeckers drum on trees to attract females◦ Male ruffed grouse fan their wings on logs and create sounds that can be

heard for miles!◦ Cranes have a courtship dance that includes stepping, bowing, stretching,

and jumping displays. Most birds are monogamous meaning a single male pairs with a

single female during the breeding season, and some birds such as swans, geese, and eagles, pair for life!! These types of pairs generally share duties of caring for the nest, eggs, and young.

Some birds are polygynous meaning the males mate with more than one female and the female care for the eggs and chicks.

A few bird species are polyandrous meaning the females mate with more than one male. The males guard the eggs in this case.

Nest construction usually begins after pair formation, but some birds do not make nests. (Example: Emperor penguins, the nest is the webbed foot of the father!)

Reproduction & Development

Group of eggs laid and chicks produced by a female is called a clutch.

Most birds incubate their eggs & birds turn the eggs to prevent the membranes from adhering to the egg and deforming the embryo!

Adults of some species sprinkle eggs with water to cool and humidify them!

One or two days before hatching, the young bird penetrates an air sac at eh blunt end of its egg, inflates its lungs, and begins breathing, then the young bird breaks free from the egg using an “egg tooth” on the tip of the upper jaw to free itself!

Altricial: totally dependent on parents and are often naked at hatching

Perocial: are alert and lively at hatching, usually covered in down feathers and can already walk, run, swim, and feed themselves (although one parent is usually present to lead the young to food and shelter)

Migration

Migration: periodic round trips between breeding and nonbreeding areas.

Most migrations are annual and allows birds to avoid climatic extremes and to secure adequate food, shelter, and space throughout the year.

Birds use two forms of navigation: ◦Route-based navigation

Involves keeping track of landmarks (visual or auditory) on an outward journey so that those landmarks can be used on the return trip

◦Location-based navigation Based on establishing the direction of the destination from

information available at the journey’s site of origin and involves the use of sun compasses, other celestial cues, and/or the earth’s magnetic field

MammalsChapter 22

General Mammal Characteristics

Skin is thick and protective and has an insulating covering of hair

Adaptations of teeth which are specialized and the digestive tract allows for a variety of food resources

Efficient circulatory and gas exchange systems support endothermy (having a body temp determined by heat derived from the animal’s own metabolism)

Brain has an expanded cerebral cortex that processes information from various sensory structures.

Specialized kidneys allow for excretion of wastes without excessive water loss.

Complex behavioral patterns enhance mammalian survival. Most mammals are viviparous and have reproductive

cycles that help ensure internal fertilization and successful development

Have mammary glands-produce milk for young

Some Orders in Class Mammalia

Order Primates: Lemurs, Monkeys, Apes, Humans

Order Rodentia: Squirrels, rats, beavers, porcupines

Order Cetacea: Whales, dolphins, porpoisesOrder Carnivora: Dogs, cats, raccoons, sea

lions, ottersOrder Proboscidea: African & Indian elephantsOrder Perissodactyla: Horses, rhinoceroses,

zebrasOrder Artiodactyla: Pigs, camels, deer, sheep,

giraffes, cattle

External Structure

Skin:◦Consists of epidermal

and dermal layers◦Protects from injury,

invasion of microorganisms, and sun’s uv light

◦ Important in temperature regulation, sensory perception, excretion, and water regulation

Hair:◦Uniquely mammalian◦A coat of hair, called

pelage, usually consists of two kinds of hair-long guard hairs & shorter, insulating underhairs.

◦Because hair is composed largely of dead cells, it must be periodically molted

Circulation & Gas Exchange

Hearts: four chambered that keep blood in the systematic and pulmonary circuits separate.

One important adaptation for mammals concerns the circulatory system distributing gases and nutrients to a fetus across the placenta

High metabolic rates require efficient gas exchange…most mammals have separate nasal and oral cavities and longer snouts, which provide for increased surface area for warming and moistening inspired air.

Mammalian lungs inflate using a negative pressure mechanism and mammals also possess a diaphragm that separates the thoracic and abdominal cavities.

Inspiration (breathing in) results from contraction of the diaphragm and expansion of the rib cage, both of which allow air to enter the lungs.

Behavior

Mammals have complex behaviors that enhance survival:◦ Visual cues

Ex: Bristled fur, arched back, and open mouth of cat communicate a clear message to predators

◦ Pheromones Ex: Young of mammals recognize parents and

parents recognize young by smell. Also, some mammals urinate to mark territories, and of course, skunks use chemicals to ward off predators

◦ Auditory Ex: Herd animals stay together and remain calm

as long as familiar sounds (hooves walking over dry grasses and twigs, stomachs rumbling) are uninterrupted.

◦ Vocalizations Ex: Humans talking in social interactions