Lecture 41- Vertebrates

Question 1

Where do vertebrates derive their name from?

Answer 1

The vertebral column, or the backbone

Question 2

When did the first vertebrae appear, and where did it live?

Answer 2

540 million years ago, in the oceans

Question 3

When did vertebrates start living on land, and what adaptation did they get to be able to achieve this?

Answer 3

360 million years ago (around 200 million years after they appeared)
They got legs, feet, and hands, etc.

Question 4

What did the vertebrates diversify into once they landed onshore?

Answer 4

Amphibia, reptiles, birds, and mammals

Question 5

How many species of vertebrae are there?

What about insects?

Answer 5

52,000 species of vertebrates

1 million insect species

Question 6

Vertebrates belong to which phylum and what are they characterized by?

Answer 6

They belong to the phylum Chordata

Characterized by Bilateral symmetry

Question 7

What are the 4 key characteristics of chordates?

Answer 7

A notochord
Dorsal, hollow, nerve cord
Pharyngeal slits or clefts
Muscular post-anal tail

Question 8

Describe and explain the notochord in chordates

Answer 8

It is a longitudinal, flexible rod located between the digestive tube and the nerve chord
Composed of large, fluid-filled cells enclosed in fairly stiff, fibrous tissue
Provides skeletal support throughout most of the chordate’s body
For most chordates, a more complex, joined skeleton develops, and the adult retains only remnants of the embryonic notochord (reduced to gelatinous disks sandwiched between the vertebrae)

Question 9

Describe and explain the Nerve chord in chordates

Answer 9

It is a dorsal, hollow nerve chord that develops from a plate of ectoderm that rolls into a tube located dorsal to the Notochord
Later develops into the central nervous system (brain and spinal chord)

Question 10

True/ False

The dorsal, hollow nerve chord is unique to chordates

Answer 10

True

Other animal phyla have SOLID nerve chords which are located VENTRALLY in most cases

Question 11

Describe and explain pharyngeal slits or clefts

Answer 11

• In ALL chordate embryos, a series of pounced seperated by grooves form along the sides of the pharynx
• In MOST chordates, these grooves known as pharyngeal Clefts develop into Slits that open to the outside of the body
• These pharyngeal slits allow water entering the mouth to exit the body w/out passing through the whole GI tract
• In aquatic vertebrates, these slits and structures supporting them are modified for gas exchange and are known as Gill Slits
• In tetrapods, the pharyngeal clefts do NOT develop into slits, instead, they play an imp role in development of the ear and other structures in the head and neck

Question 12

Describe the muscular, post anal tail

Answer 12

Chordates have a tail extending posterior to the anus.
However, in most species it is lost during embryonic development
The tail contains skeletal elements and muscles, and provides much of the propelling force in many aquatic species

Question 13

What are craniates?

Answer 13

It is a subphylum of chordates that are evolved further from basic chordates. (Next major transition of chordate evolution)
Craniates that posess a head
This head consists of a brain at at the anterior end cod the dorsal nerve chord, eyes and other sensory organs and a skull
They have a higher metabolism and more extensive muscular system
They also have a heart with AT LEAST 2 CHAMBERS, RBC, haemoglobin as well as kidneys thst remove waste products from the blood

Question 14

What are vertebrates?

Answer 14

They are a more evolved from of craniates that developed a more complex nervous system, more elaborate skeleton, and most importantly Vertebrae.
For Most of vertebrates, the vertebrae encloses the spinal chord and has taken over the mechanical roles of the notochord.
Aquatic vertebrates also acquire dorsal, ventral, and anal fins stiffened by fin rays which provides thrust and steering control during swimming

Question 15

What are Gnasthostomes?

Answer 15

Vertebrates that have jaws

Question 16

Describe tetrapods

Answer 16

They are gnothostomes that have limbs or feet
About 360 million years ago, the fins of some vertebrates evolved into limbs and fet of tetrapods (can now live in land)
Before that, they had basic fishlike anatomy
These include frogs, eagles, and bipedal humans

Question 17

Describe Amniotes

Answer 17

They are tetrapods that have terestrially adapted egg (amniotic egg)
This amniotic egg contains extra-embryonic specialized membranes that protect the embryo
These membranes develop from tissue layers that grow out from the embryo ( Allantoid, Chorion, Amnion, and yolk sac_
The egg is usually protected by a shell
They also acquire other adaptations of terrestrial lives such as less permeable skin, and the ability to use the Rib cage to ventilate the lungs

Question 18

Describe the Extraembryonic membranes of amniotes

Answer 18

Allantois- a disposable sac for certain metabolic wastes produced by the embryo. The membrane functions with the chorion as a respiratory organ
Chorion- it functions with the membrane of the allontoks to exchange gases between the embryo and air. O2 and CO2 diffuse freely across the shell
Yolk sac- contains the yolk, a stockpile of nutrients. Blood vessels in the yolk membrane transport nutrients from the yolk and into the embryo. Other nutrients are stored in albumin (in case of real egg)
Amnion- protects the embryo in a fluid filled cavity against mechanical shock

Question 19

Describe Mammals

Answer 19

They are amniotes that have hair and produce milk
They are one of the 2 main lineages of amniotes (other being reptiles)
2 unique characteristics are
-Mammary glands
-Hair and fat layer under the skin- help body retain heat
They also have efficient respiratory and circulatory systems
Sheet of muscle clalled diaphragm to help ventilate lungs
Larger brain than other vertebrates of equal size
Differentiation of teeth (Reptiles have uniform, conical teeth)
4 chambered heart

Question 20

How many species of mammals are there?

Answer 20

5000 species

Question 21

The order primates of ,a,males include what families?

Answer 21

Lemurs
Tarsiers
Monkeys
Apes

Question 22

Describe primates

Answer 22

Most primates have hands and feets adapted for grasping and their digits have flat balls instead of narrow claws of other mammals
Large brain and short hawks giving them a flat face
Well developed parental care and complex social behavior

Question 23

What genera are inside the family hominoids?

Answer 23

Hylobates (gibbons)
Poncho (orangutans)
Gorilla 
Pan (chimpanzees and bonobos)
Homo (humans)

Question 24

How do hominids compare with other primates?

Answer 24

Larger brain proportional to body system

Behavior is more flexible

Question 25

When did Homo sapiens arrive?

Answer 25

160,000 years ago

Question 26

Describe humans

Answer 26

Bipedal hominids with a large brain
Capable of language, symbolic thought, can use complex tools
Reduced jawbones and jaw muscles
Shorter GI tract
Approx 3 Billion base pairs in human genome (99% identical to chimps)

Question 27

The study of the origin of humans is

Answer 27

Paleoanthropology

It claims that there are 20 species of hominoids closer to humans as compared to chimps

Question 28

Classification of human being
Phylum 
Class
Order
Family
Genus
Species

Answer 28

Phylum- Amniotes
Class- Mammals
Order- Primates
Family- Hominoidesn(apes)
Genus - Homo
Species- Homo sapiens

Question 29

When was the oldest known fossil of H sapiens found, and where was it found?

Answer 29

In 2003 in Ethiopia

It was 160,000 year old fossil

Question 30

What was the sequence of Human migration?

Answer 30

Africa-> Asia-> Asia-> Europe-> Australia-> America