Lecture 41- Vertebrates Flashcards
Where do vertebrates derive their name from?
The vertebral column, or the backbone
When did the first vertebrae appear, and where did it live?
540 million years ago, in the oceans
When did vertebrates start living on land, and what adaptation did they get to be able to achieve this?
360 million years ago (around 200 million years after they appeared)
They got legs, feet, and hands, etc.
What did the vertebrates diversify into once they landed onshore?
Amphibia, reptiles, birds, and mammals
How many species of vertebrae are there?
What about insects?
52,000 species of vertebrates
1 million insect species
Vertebrates belong to which phylum and what are they characterized by?
They belong to the phylum Chordata
Characterized by Bilateral symmetry
What are the 4 key characteristics of chordates?
A notochord
Dorsal, hollow, nerve cord
Pharyngeal slits or clefts
Muscular post-anal tail
Describe and explain the notochord in chordates
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)
Describe and explain the Nerve chord in chordates
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)
True/ False
The dorsal, hollow nerve chord is unique to chordates
True
Other animal phyla have SOLID nerve chords which are located VENTRALLY in most cases
Describe and explain pharyngeal slits or clefts
- 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
Describe the muscular, post anal tail
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
What are craniates?
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
What are vertebrates?
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
What are Gnasthostomes?
Vertebrates that have jaws
Describe tetrapods
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
Describe Amniotes
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
Describe the Extraembryonic membranes of amniotes
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
Describe Mammals
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
How many species of mammals are there?
5000 species
The order primates of ,a,males include what families?
Lemurs
Tarsiers
Monkeys
Apes
Describe primates
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
What genera are inside the family hominoids?
Hylobates (gibbons) Poncho (orangutans) Gorilla Pan (chimpanzees and bonobos) Homo (humans)
How do hominids compare with other primates?
Larger brain proportional to body system
Behavior is more flexible
When did Homo sapiens arrive?
160,000 years ago
Describe humans
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)
The study of the origin of humans is
Paleoanthropology
It claims that there are 20 species of hominoids closer to humans as compared to chimps
Classification of human being Phylum Class Order Family Genus Species
Phylum- Amniotes Class- Mammals Order- Primates Family- Hominoidesn(apes) Genus - Homo Species- Homo sapiens
When was the oldest known fossil of H sapiens found, and where was it found?
In 2003 in Ethiopia
It was 160,000 year old fossil
What was the sequence of Human migration?
Africa-> Asia-> Asia-> Europe-> Australia-> America
