Kingdom AnimaliaPhylum Chordata

The vertebrates and their relatives

Phylum Chordata

• Characteristics of a chordate – A dorsal hollow nerve cord (spinal cord in

vertebrates)– A notochord (most vertebrates only have a

notochord during development – becomes the backbone in vertebrates)

– Pharyngeal Pouches (develop into gills in fish and amphibians)

– Muscular Tail (disappears in humans)

Subphylum Urochordata

• Tunicates (also known as “sea squirts”)– Look similar to other chordates during

development, but completely different as adults

Subphylum Cephalochordata

• Lancelets: live in the ocean with their body buried in sand– Have a definite mouth and no jaws– Long pharynx with up to 100 gill slits– Breathe through their body surface– Have a simple digestive system, heart, and closed

circulation– Use paired muscles to move

Subphylum Vertebrata

• 99% of chordates are vertebrates – Fish 24,000 species– Amphibian 4,000 species– Reptiles 6,000 species– Birds 10,000 species– Mammals 4,500 species

Fishes

• Aquatic vertebrates characterized by:– Fins (Movement)– Scales (Protection)– Gills (Breathing)

• There are fish with exceptions!– Can you name any?

Fish Evolution

• Fish were the first vertebrate to evolve

• Evolved about 540 mya– Were jawless and covered in armored plates

• Devonian Period = Age of the Fishes– Fish developed both jaws and fins at this time

Body Systems of Fishes

• Fish feed in a variety of ways including parasites, carnivores, herbivores, etc.

• Most fish breathe using gills– Gills are feathery filaments containing a network of capillaries to

increase surface area for CO2 and O2 exchange

• Fish have closed circulation

Body Systems of Fishes

• Fish digestive systems are similar to that of humans

• Ammonia is excreted by diffusion of water through gills and by use of kidneys– Salt water fish conserve bodily fluids by

having concentrated urine– Fresh water fish have dilute urine– Fish that move from fresh to salt water alter

their kidney function to adapt to tonicity!

Fish Senses

• Fish exhibit cephalization

• Many fish have Chemoreceptors for an extraordinary sense of taste and smell

• Lateral Line System – allows fish to sense movement and vibration

Fish Senses

• Swim Bladder – adjust buoyancy – How does pulling a fish from 40 feet of water

affect the size of its swim bladder?

Fish Reproduction

• Oviparous – egg laying; includes both internal (some sharks) and external (most fishes) fertilization

• Ovoviviparous – eggs develop inside mother’s body and are nourished by egg yolk; young are born alive

• Viviparous – the mother’s body nourishes the developing young which are born alive

Groups of Fishes

• Class Cephalospidomorphi – lamprey

• Class Myxini – hagfishes

• Class Chondrichthyes – cartilaginous fishes

• Class Osteichthyes – bony fishes

Lamprey and Hagfishes

• Are jawless fishes– Have mouths of soft tissue and no true teeth

• Have no bones

• Are the only vertebrates that do not have vertebral columns as adults

Lamprey

• Are filter feeders as larvae and parasites that suck blood and tissues of fish as adults

Hagfishes

• Feed on dead and dying fish using a toothed tongue to scrape a hole in the fishes side

• Secrete large amounts of slime

• Have 6 hearts and an open circulatory system

Cartilaginous Fishes

• Includes sharks, rays, skates, sawfishes, and chimaeras

• “Chondros” = Greek word for cartilage • A typical shark has 3000 teeth arranged in

6 to 20 rows• Not all are carnivores, the largest sharks

are filter feeders • Some have flat teeth for crushing mollusks

and crustaceans

Bony Fishes

• Skeletons are made of calcified bone

• Includes fish we are most familiar with: Sunfish, Muskellunge, Northern Pike, Walleye, Smallmouth Bass, etc.

Fish Ecology

• Some fish can live in both salt water and fresh water – Anadromous Fishes – spend most of their

life in the ocean but move to fresh water to breed

– Catadramous Fishes – spend most of their life in fresh water but move to the ocean to breed

Class Amphibia

• Amphibians gave rise to all other land vertebrates

• Amphibian means “double life” – As larvae they are typically aquatic filter

feeders or herbivores breathing through gills– As adults most species are terrestrial

carnivores that breathe through their moist skin and have lungs

Adaptations to Life on Land

• As the amphibians developed in the late Devonian Period 360 mya they needed to adapt to terrestrial life– Keep from drying out– Breathe using lungs, not gills– Bones in limbs allow movement– Ribs to support and protect internal organs

• Amphibians dominated the Carboniferous Period 345 to 285 mya

Amphibian Body Systems• Amphibians have a well developed

digestive system similar to that of humans• As most amphibians develop lungs as

adults, some are lung-less and only breathe through their skin

• They have closed circulation and a 3 chambered heart with a double loop system similar to that of a human

• Ammonia is disposed of in urine through the use of kidneys

Amphibian Reproduction

• Most amphibians lay their eggs in water; fertilization is external

• Some salamanders fertilize internally

Amphibian Reproduction

• In most cases of external fertilization, the male will attach itself to the female. Eggs and sperm are released simultaneously and encapsulated in a jelly that attaches to aquatic plants.

• The jelly nourishes the developing embryos

• Tadpoles hatch and metamorphose into adults

Amphibian Reproduction

• Most amphibians abandon their eggs once they lay them.

• Some care for both eggs and young

• Some incubate their eggs in unusual places: in their mouth, on their back, or in their stomach

Amphibian Senses

• Amphibians have a well developed brain and spinal cord similar to that of a fish

• Eye’s are protected by a nictitating membrane

• A tympanic membrane, or eardrum, is located on either side of the head

• Many have a lateral line system similar to that of a fish

Groups of Amphibians

• Order Urodela: Salamanders and Newts

• Order Anura: Frogs and Toads

• Order Apoda: Caecilians

Salamanders and Newts

• Have long bodies and tails

• Both adults and larvae are carnivores

• Most adults are terrestrial and live in damp forests

• Some salamanders, such as mud puppies, keep their gills and live in water all their lives

Frogs and Toads

• Have the ability to jump

• Frogs have longer legs and can jump farther than toads

• Frogs are closely tied to water; toads are more terrestrial

Caecilians

• Least known of the amphibians

• Are legless and burrow in moist soil or sediment

• Feed on small invertebrates such as termites

• Some have scales

Amphibian Ecology

• Most are a great meal for birds and reptiles

• Some have toxins to poison predators

• Some have bright colors to warn of their toxins

• Some mimic the bright colors of others and are harmless

Amphibian Ecology

• Amphibian populations are declining worldwide due to several factors:– Global Warming– Decreasing Habitat– Depletion of the Ozone– Water Pollution– Introduced Aquatic Predators– Fungal Infections– Increasing human population!

Class Reptilia

• Land vertebrates with a well developed skull, a backbone and tail, and four limbs– Exemptions: snakes have no legs, and turtles

have a shell formed of fused vertebrae?

• Can a turtle lose its shell?

Reptile Evolution

• The oldest reptile fossils date back to the early Carboniferous Period some 350 million years ago

• Dinosaurs of the Triassic and Jurassic Period ruled the earth until 65 million years ago

Reptile Body Systems

• Reptiles are ectotherms – rely on interactions with the environment to control their body temperature

• Reptiles have well developed lungs, four chambered hearts, and a well developed brain and spinal cord

• Reptiles’ legs are rotated farther under their body than amphibians allowing them to carry weight and walk on land more efficiently

Reptile Reproduction

• Internal Fertilization – males have a penis to place sperm in the female’s cloaca

• Most are oviparous– Turtles leave their nests unattended while

alligators protect their nest

• Some snakes are ovoviviparous

Reptilian Eggs

• Reptiles have amniotic eggs – named after one of the four membranes around the developing embryo– Amnion: produces watery environment

around embryo– Yolk Sac: contains nutrient rich yolk that

feeds embryo– Chorion: allows gas exchange– Allantois: stores waste

Groups of Reptiles

• Order Squamata: lizards and snakes

• Order Crocodilia: alligators, crocodiles, caimans, and gavials

• Order Chelonia: turtles, tortoises, terrapins

• Order Rhynchocephalia - tuataras

Lizards and Snakes

• Most lizards have legs, clawed toes, external ears, and movable eyelids

• Some lizards do not have legs and look more like a snake

Alligators, Crocodiles, and their Relatives

• Long broad snout and squat appearance

• Fierce carnivores• Very protective of their

nests• Alligators and Caimans

live only in fresh water and almost exclusively in North and South America

• Crocodiles live in both fresh and salt water and are native to Africa, India, and Southeast Asia

Turtles, Tortoises, and Terrapins

• Turtles – live in or near water

• Tortoises – are terrestrial

• Terrapins – live in brackish water

– Carapace: Dorsal side of Shell

– Plastron: Ventral side of Shell

Tuataras

• Tuataras are the only living member of the Order Rhynchocephalia

• Beak headed reptiles that live on a few small islands off the coast of New Zealand

• Differ from lizards as they lack external ears and retain primitive scales

• They have a legendary “third eye” which is part of a complex organs on top of the brain – the function is unknown

Ecology of Reptiles

• Many are in danger due to loss of habitat

• Humans also hunt them for food, pets, and their skins (for bags and boots)

• Many conservation efforts are underway, but more are needed worldwide

Class Aves

• Characteristics of most birds– Maintain a constant

internal body temperature

– Covered in feathers– Have two legs for

walking and perching– Front limbs are wings– Most are adapted for

flight

Feathers

• Used for flight and warmth; several types– Contour Feathers: provide the lifting force and balance needed

for flight– Down Feathers: trap air close to the body and keep the bird warm– Powder Down: found on ducks and other birds that live on or in

water; release a fine powder that repels water

Evolution of Birds• Oldest known fossil is Archaeopteryx

which lived during the Jurassic Period 150 mya.– Had teeth in its beak, a jointed tail, and toes

and claws on its wings

• Birds are very closely related to dinosaurs, but scientists disagree on whether birds evolved from dinosaurs – or- birds and dinosaurs evolved from one common ancestor

Body Systems of Birds

• Endotherms: can generate their own body heat; warm-blooded

• Smaller birds must eat more in relation to its size due to Surface Area to Volume Ratio

Feeding habits of Birds

• They lack teeth and therefore do not chew

• Beaks are adapted to the types of food they eat

• Bird Digestion– Crop: enlargement of the esophagus used to

store food– Gizzard: has muscular walls and small bits of

gravel used to grind food

Respiration

• Birds have very efficient lungs that provide oxygen rich blood during both inhalation and exhalation

• Inhaled air enters posterior and anterior air sacs it then travels through the lungs and is exhaled

• Therefore the air flows into the air sacs and out of the lungs in one single direction, always providing oxygen rich air

Circulation and Excretion

• Two loop circulatory system, similar to that of humans

• Ammonia is removed by the kidneys, converted to high concentration uric acid and defecated (bird droppings); similar to reptiles

Senses of Birds

• The brains of birds are very well developed– Birds can see color very well– Birds can hear very well– Smell or taste are not well developed

Bones and Muscles

• Most birds can fly. Others are adapted for swimming and running

• Bones are light, strong, and adapted for flight; many bones are fused to provide a study base for flight adaptations

Bird Reproduction

• Both male and female reproductive tracts open into the cloaca

• The sex organs, internal in both sexes, increase in size during mating season

• Birds rub their cloacas together during mating to transfer sperm

Eggs and Incubation

• Eggs are amniotic but unlike reptile eggs have a hard outer shell

• Eggs must be incubated by the parents since they are endotherms

• Young must be cared for after hatching

Groups of Birds

• There are nearly 30 different orders of birds

• 60% of all birds worldwide are perching birds

• Show many examples!

Ecology of Birds• Birds are very ecologically important

– Hummingbirds are involved in pollination– Some birds eat seeds without digesting them

and therefore spread the seeds– Many birds keep insect populations in check

• Many birds migrate by guidance of stars, Earth’s landmarks, and Earth’s magnetic field

• Birds are good indicators of environmental health; bird numbers dwindled with the use of DDT

Class Mammalia

• Characteristics of mammals– Endotherms– Have mammary glands and nurse young– Have hair

Evolution of Mammals

• The earliest mammals evolved about the same time as the early dinosaurs but remained in the shadows until the giant reptiles disappeared

• First ancestors of mammals appeared during the Permian Period about 290 to 250 mya

• First true mammals appeared during the Jurassic Period 210 mya

Mammal Evolution

• When the continents split about 60 mya, three groups of mammals were isolated from one another.

Staying Warm

• Animals have hair to help insulate their bodies.

• They also have subcutaneous fat to keep them warm and many have sweat glands to cool them off.

• Smaller mammals have higher metabolism than larger ones in order to create enough body heat to keep warm.

• Mammals eat about 10 times as much food as a reptile in order to stay warm.

Comparison of Vertebrate Forelimbs

• When comparing the bones and bone structures of all vertebrates - birds, amphibians, reptiles, and mammals – you can see many of the same bones with very similar functions

• Refer to Figure 32-7 in the text (Page 826)

Mammal Reproduction

• Internal Fertilization occurs in mammals

• Mammals are divided into three groups based on methods of development and birth– Oviparous: egg-laying mammals are called

monotremes– Viviparous: includes both placental mammals

and marsupials

Caring for Young

• All newborn mammals feed on their mother’s milk

• Some newborns are helpless at birth and must be cared for

• Others are able to see and walk within minutes after birth

Monotremes

• Monotremes are the egg laying mammals

• They share two notable characteristics with reptiles– Both the reproductive and

urinary systems open into a cloaca

– “Monotreme” means single opening

• Only three species of monotremes exist today: they are found in Australia and New Guinea– Duckbill Platypus and two

species of Spiny Anteaters

Laying eggs and caring for young

• Monotremes lay eggs that are incubated outside the body

• They hatch into young animals in about 10 days

• The young are nourished by their mother’s milk that they lick from pores on the mother's abdomen

Marsupials

• Marsupials give birth to live young that complete their development in an external pouch

• Examples include kangaroos, wombats, koalas, and Tasmanian devils

• A short time after internal fertilization a small embryo leaves the mother’s body, crawls across the fur, and enters the marsupium (pouch) where it attaches to a nipple to nurse

Placental Mammals

• Placental Mammals are those that are most familiar to us.

• Placenta – organ in placental mammals through which nutrients, oxygen, carbon dioxide, and wastes are exchanged between embryo and mother

• Gestation – the time it takes from conception to birth in mammals (can vary from 2 weeks to 2 years depending on the mammal)

Orders of Mammals

• There are 12 orders of placental mammals

• They are classified based on several criteria including– Feeding– Teeth and Jaw Structure– Foot Structure– Brain Development