1. Chordates have a notochord and a dorsal, hollow nerve cord
Vertebrates are a subphylum of phylum Chordata
Chordates are bilaterian animals that belong to the clade of animals known as Deuterostomia
Two groups of invertebrate deuterostomes, the urochordates and cephalochordates, are more closely related to vertebrates than to invertebrates

2. Derived Characters of Chordates
All chordates share a set of derived characters
Some species have some of these traits only during embryonic development
Four key characters of chordates:
Notochord
Dorsal, hollow nerve cord
Pharyngeal slits or clefts
Muscular, post-anal tail

3. Dorsal,
hollow
nerve cord
Muscle
segments
Brain
Notochord
Mouth
Anus
Pharyngeal
slits or clefts
Muscular,
post-anal tail

4. Notochord
The notochord is a longitudinal, flexible rod between the digestive tube and nerve cord
It provides skeletal support throughout most of the length of a chordate
In most vertebrates, a more complex, jointed skeleton develops, and the adult retains only remnants of the embryonic notochord

5. Dorsal, Hollow Nerve Cord
The nerve cord of a chordate embryo develops from a plate of ectoderm that rolls into a tube dorsal to the notochord
The nerve cord develops into the central nervous system: the brain and the spinal cord

6. Pharyngeal Slits or Clefts
In most chordates, grooves in the pharynx called pharyngeal clefts develop into slits that open to the outside of the body
Functions of pharyngeal slits:
Suspension-feeding structures in many invertebrate chordates
Gas exchange in aquatic vertebrates
Develop into parts of the ear, head, and neck in terrestrial vertebrates

7. Muscular, Post-Anal Tail
Chordates have a tail posterior to the anus
In many species, the tail is lost during embryonic development
The tail contains skeletal elements and muscles
It provides propelling force in many aquatic species

8. Craniates are chordates that have a head
The origin of a head opened up a completely new way of feeding for chordates: active predation
Craniates share some characteristics: a skull, brain, eyes, and other sensory organs

9. Hagfishes
The least derived surviving craniate lineage is class Myxini, the hagfishes
Hagfishes are jawless marine craniates that have a cartilaginous skull and axial rod of cartilage derived from the notochord and lack vertebrae

10. Slime glands

11. Derived Characters of Vertebrates
Vertebrates have the following derived characters:
Vertebrae enclosing a spinal cord
An elaborate skull
Fin rays, in aquatic forms

12. Lampreys
Lampreys, class Cephalaspidomorphi, represent the oldest living lineage of vertebrates
They are jawless vertebrates inhabiting various marine and freshwater habitats
They have cartilaginous segments surrounding the notochord and arching partly over the nerve cord

14. Chondrichthyans (Sharks, Rays, and Their Relatives)
Members of class Chondrichthyes have a skeleton composed primarily of cartilage
The cartilaginous skeleton evolved secondarily from an ancestral mineralized skeleton
The largest and most diverse subclass of Chondrichthyes includes the sharks and rays

15. Pelvic fins
Pectoral fins
Blacktip reef shark (Carcharhinus melanopterus).

16. Ray-Finned Fishes and Lobe-Fins
The vast majority of vertebrates belong to a clade of gnathostomes called Osteichthyes
Nearly all living osteichthyans have a bony endoskeleton
Aquatic osteichthyans are the vertebrates we informally call fishes
Fishes control their buoyancy with an air sac known as a swim bladder
Fishes breathe by drawing water over gills in chambers covered by a bony flap called the operculum

17. Swim
bladder
Dorsal fin
Adipose fin
(characteristic
of trout)
Caudal
fin
Spinal cord
Brain
Nostril
Cut edge
of operculum
Anal fin
Lateral
line
Liver
Gills
Anus
Heart
Gonad
Kidney
Stomach
Urinary
bladder
Pelvic
fin
Intestine

18. Ray-Finned Fishes
Class Actinopterygii, the ray-finned fishes, includes nearly all the familiar aquatic osteichthyans
The fins, supported mainly by long, flexible rays, are modified for maneuvering, defense, and other functions

19. Clownfish

20. Lobe-Fins
The lobe-fins, class Sarcopterygii, have muscular and pectoral fins
They include coelacanths, lungfishes, and tetrapods

21. Tetrapods are gnathostomes that have limbs and feet
One of the most significant events in vertebrate history was when the fins of some lobe-fins evolved into the limbs and feet of tetrapods
Tetrapods have some specific adaptations:
Four limbs and feet with digits
Ears for detecting airborne sounds

22. Amphibians
Most amphibians have moist skin that complements the lungs in gas exchange
Amphibian means “two lives,” referring to the metamorphosis of an aquatic larva into a terrestrial adult

23. Order Urodela includes salamanders, which have tails
Order Anura includes frogs and toads, which lack tails
Order Apoda includes caecilians, which are legless and resemble worms

24. Order Urodela. Urodeles (salamanders)
retain their tail as adults.

25. Order Anura. Anurans, such as this poison
arrow frog, lack a tail as adults.

26. Order Apoda. Apodans, or caecilians,
are legless, mainly burrowing amphibians.

27. The male grasps the female, stimulating her to release eggs
The male grasps the female, stimulating her to release eggs. The eggs are laid and fertilized in water. They have a jelly coat but lack a shell and would desiccate in air.

28. Amniotes are tetrapods that have a terrestrially adapted egg
Amniotes are a group of tetrapods whose living members are the reptiles, including birds, and the mammals
Amniotes are named for the major derived character of the clade, the amniotic egg, which contains membranes that protect the embryo
The extraembryonic membranes have various functions
Amniotes have other terrestrial adaptations, such as relatively impermeable skin and the ability to use the rib cage to ventilate the lungs

29. Extraembryonic membranes
Amnion
Allantois
Chorion
Yolk sac
Embryo
Amniotic cavity
with amniotic fluid
Yolk (nutrients)
Shell
Albumen

30. Reptiles
The reptile clade includes the tuatara, lizards, snakes, turtles, crocodilians, birds, and the extinct dinosaurs
Reptiles have scales that create a waterproof barrier
They lay shelled eggs on land
Most reptiles are ectothermic, absorbing external heat as the main source of body heat

31. Turtles Turtles are the most distinctive group of reptiles alive today
All turtles have a boxlike shell made of upper and lower shields that are fused to the vertebrae, clavicles, and ribs

32. Eastern box turtle (Terrapene carolina carolina)

33. Alligators and Crocodiles
Crocodilians belong to an archosaur lineage that dates back to the late Triassic
American alligator (Alligator mississipiensis)

34. Birds
Birds are archosaurs, but almost every feature of their reptilian anatomy has undergone modification in their adaptation to flight
Birds are endothermic, capable of keeping the body warm through metabolism
Many characters of birds are adaptations that facilitate flight

35. Finger 1
Bone structure
Palm
Wing
Finger 2
Finger 3
Forearm
Wrist
Shaft
Shaft
Vane
Barb
Barbule
Hook
Feather structure

36. Mammals are amniotes that have hair and produce milk
Mammary glands, which produce milk, are a distinctively mammalian character
Hair is another mammalian characteristic
Mammals generally have a larger brain than other vertebrates of equivalent size

37. Monotremes are a small group of egg-laying mammals consisting of echidnas and the platypus
Marsupials include opossums, kangaroos, and koalas
A marsupial is born very early in its development
It completes its embryonic development while nursing in a maternal pouch called a marsupium

38. Short-beaked echidna (Tachyglossus aculeatus),
an Australian monotreme. Monotremes have hair
and produce milk, but they lack nipples. Monotremes are the only
mammals that lay eggs (inset).

39. A young brushtail possum
A young brushtail possum. The young of marsupials are born very early in their development. They finish their growth while nursing from a nipple (in their mother’s pouch in most species).

40. Marsupial mammals
Eutherian mammals
Plantigale
Deer mouse
Marsupial mole
Mole
In Australia, convergent evolution has resulted in a diversity of marsupials that resemble eutherians in other parts of the world
Sugar glider
Flying squirrel
Wombat
Woodchuck
Wolverine
Tasmanian devil
Patagonian cavy
Kangaroo

41. Eutherians (Placental Mammals)
Compared with marsupials, eutherians have a longer period of pregnancy
Young eutherians complete their embryonic development within a uterus, joined to the mother by the placenta
The mammalian order Primates includes lemurs, tarsiers, monkeys, and apes
Humans are members of the ape group

42. Derived Characters of Primates
Most primates have hands and feet adapted for grasping
Other derived characters of primates:
A large brain and short jaws
Forward-looking eyes close together on the face, providing depth perception
Well-developed parental care and complex social behavior
A fully opposable thumb

43. Animations and Videos Bozeman - Animal Characteristics
Life Cycle of a Frog
Chapter Quiz Questions – 1
Chapter Quiz Questions - 2