Vertebrates (lecture 18)

Question 1

What are vertebrates?

Answer 1

Vertebrates are animals with a backbone.

Question 2

Are all members of the Phylum Chordata vertebrates?

Answer 2

No, not all members of the Phylum Chordata are vertebrates.

Question 3

What are the two subphylums under under the Phylum Chordata.

Answer 3

Phylum Chordata can be broken down into two subphylums; the invertebrates and the vertebrates.

Question 4

What 4 characteristics appear at some point in the life time of members of the Phylum Chordata?

Answer 4

A notochord; a dorsal, hollow nerve cord; a muscular, post-anal tail; pharyngeal slits or clefts.

Question 5

What is the notochord? (Phylum Chordata)

Answer 5

The notochord is a longitudinal, flexible rod between the digestive tract and the nerve cord. It is composed of large, fluid-filled cells covered in stiff fibrous tissue. The notochord provides skeletal support and in adult vertebrates, it forms intervertebral discs.

Question 6

What is the dorsal, hollow nerve cord? (Phylum Chordata)

Answer 6

The dorsal, hollow nerve cord develops into the brain and spinal cord (the central nervous system).

Question 7

What are the Pharyngeal slits or clefts? (Phylum Chordata)

Answer 7

The Pharyngeal slits or clefts connect the pharynx to the outside and allow water to enter the mouth and exit without going through the digestive system; filter-feeding in chordate invertebrates.

Question 8

During chordate embryonic development, what do the pharyngeal slits or clefts develop into?

Answer 8

During embryonic development in aquatic vertebrates, the pharyngeal slits or clefts develop into the gills (gas exchange). In vertebrates without gills the pharyngeal slits or clefts develop into the bones in the jaw and inner ear (jaw support and hearing).

Question 9

What is the muscular post-anal tail? (Phylum Chordata)

Answer 9

This contains skeletal elements and muscles. It can be used for swimming, climbing & communication. It is vestigial in humans, meaning it has lost its use and is now only briefly present in humans during embryonic development.

Question 10

Members of the subphylum invertebrates have no _____ _____. The support is instead provided by the _____. Both _____ and _____ are invertebrate members of the Phylum Chordata.

Answer 10

Members of the subphylum invertebrates have no vertebral column. The support is instead provided by the notochord. Lancelets and tunicates are invertebrate members of the Phylum Chordata.

Question 11

Members of the subphylum vertebrata are animals that do have a _____ _____. Furthermore, the _____ is reduced into _____ _____ during development.

Answer 11

Members of the subphylum vertebrata are animals that do have a vertebral column. Furthermore, the notochord is reduced into intervertebral discs during development.

Question 12

Members of the subphylum vertebrata have increased _____, meaning an increased _____ of _____ organs and neural equipment in the _____.

Answer 12

Members of the subphylum vertebrata have increased cephalization, meaning an increased concentration of sensory organs and neural equipment in the head.

Question 13

Members of the subphylum vertebrata have skeletons. Describe it’s primary components, its composition and its functions.

Answer 13

Their skeletons include the cranium and vertebral column, composed of either bone, cartilage or both. The skeleton provides support allowing for larger body size, stronger movements and faster movements.

Question 14

Members of the subphylum Vertebrata all have _____ _____ systems, with a __ - __ _____ heart, arteries, _____ and veins. Their blood is oxygenated as it passes through the _____ or _____.

Answer 14

Members of the subphylum Vertebrata all have closed circulatory systems, with a 2 - 4 chambered heart, arteries, capillaries and veins. Their blood is oxygenated as it passes through the lungs or gills.

Question 15

What is the difference between veins, arteries and capillaries?

Answer 15

Arteries carry blood away from the heart, veins carry blood to the heart. In between both are the capillaries, which is the site of gas exchange with cells.

Question 16

What was a consequence of the development of the vertebral column in vertebrates?

Answer 16

The vertebral column allowed for transition from a sedentary to an active life-style, with respiratory and circulatory systems being more efficient. This increased their feeding, digestion and nutrient absorption capabilities.

Question 17

There are six groups of vertebrates, put into 5 classes. What are these 5 classes and which ones house 2 of the 6 groups?

Answer 17

These classes are Class Chondrichthyes, Class Actinopterygii, Class Amphibia, Class Reptilia (including birds) & Class Mammalia.

Question 18

What are the evolutionary breakthroughs associated with the emergence of Chondrichthyes.

Answer 18

The evolutionary breakthrough associated with the emergence of Chondrichthyes are jaws and paired fins.

Question 19

Describe the Class Chondrichthyes.

Answer 19

They are cartilaginous fish (sharks and stingrays), meaning they have a flexible endoskeleton made of cartilage (chondroitin sulfate). They have very acute senses and fertilization is internal.

Question 20

Describe members of the Class Actinopterygii.

Answer 20

Ray-finned fish have an endoskeleton made of a hard matrix of calcium phosphate (bone). Their skin is covered in flattened scales. During respiration, water is drawn into the mouth and passes through 4-5 pairs of gills (where gas exchange occurs). Fertilization and development is external. These fish have a swim bladder (precursor to lungs), which is an air filled sac that provides buoyancy (when filled with air, the swim bladder causes the fish to rise up). Actinopterygii have a 2-chambered heart.

Question 21

Why don’t sharks need a swim bladder?

Answer 21

Because sharks are like airplanes; their fins act like the wings on an airplane, they can angle them to go either up or down (because they must always be moving forwards to perform respiration).

Question 22

Class Amphibia consist of _____, _____, _____ and _____. They evolved from _____ that lived in _____ _____ (they are the first land vertebrates) and can live on both _____ and on _____.

Answer 22

Class Amphibia consist of frogs, salamanders, toads and newts. They evolved from fish that lived in shallow water (they are the first land vertebrates) and can live on water and on land.

Question 23

Why can’t amphibians live in the absence of water?

Answer 23

They cannot live in the absence of water because water is required for reproduction and development.

Question 24

What advantage do amphibians have by being able to live both on water and on land?

Answer 24

The ability to live on both water and land gave them the ability to escape predators more easily and gave them access to an increased food supply.

Question 25

Describe amphibian respiration.

Answer 25

As adults, they perform respiration using lungs. As larvae, they use gills (larvae require water to breathe). Amphibians can also breathe through their skin.

Question 26

Describe the fertilization and development of amphibians.

Answer 26

Fertilization and development is external.

Question 27

Amphibians have a __-_____ heart.

Answer 27

Amphibians have a 3-chambered heart.

Question 28

Describe the members and characteristics of the amniotes.

Answer 28

Out of the six groups of vertebrates, 3 share certain characteristics. These characteristics are; an amniotic egg; waterproof skin; the use of the ribcage for breathing. Class Reptilia, birds and Class Mammalia share these characteristics, meaning they are amniotes.

Question 29

Describe the amniotic egg.

Answer 29

The amniotic egg led to the increased success of vertebrates on land, since the shell prevents desiccation (no shell in mammals; embryo implants in wall of uterus), the eggs contain their own water supply (albumen / egg white) and so the eggs can survive on land. The extra embryonic membranes of an amniotic egg function in gas exchange, waste storage and the transfer of stored nutrients to the embryo.

Question 30

Describe the class Reptilia.

Answer 30

Lizards, snakes, turtles, crocodiles and alligators are all reptiles. They have scales containing the protein keratin and that helps prevent drying out. They have lungs for respiration and fertilization is internal (the egg is laid after fertilization). They are ectothermic (cold-blooded), meaning that they do not use metabolism to regulate body temperature. Instead, they control their body temperatures behaviorally (sit in the sun when cool and in the shade when hot).

Question 31

What do birds (flying reptiles) have in common with the rest of the class Reptilia?

Answer 31

Like other reptiles, they can produce an amniotic egg and they have scales on their legs.

Question 32

In what way is the anatomy of birds different from other reptiles and why is this the case?

Answer 32

Their anatomy is designed to enhance flight. They have a reduced weight; only one ovary, no teeth (gizzard, a part of the digestive tract, grinds food instead) and their bones have a honeycomb structure. They also have feathers, wings and a well developed nervous system (acute vision, able to coordinate flying).

Question 33

Explain how birds meet the energy demands of flying.

Answer 33

Since flying requires a lot of energy, they have a very active metabolism, an efficient respiratory and circulatory system (with a 4-chambered heart). Birds are endothermic, unlike the other reptiles, meaning that they can regulate their body temperature by metabolism.

Question 34

What is the benefit of flight? (birds)

Answer 34

Flight grants birds the ability to better escape predators, it allows birds to find prey easier and it expands their habitat range, which expands their food supply (and resources in general).

Question 35

Describe bird reproduction.

Answer 35

Fertilization is internal. Eggs are laid afterwards.

Question 36

Describe the class Mammalia.

Answer 36

Mammalia have mammary glands that produce milk to nourish the young. They have hair composed of keratin that provides insulation (the fat under their skin also retains heat). They are endothermic, meaning they have an active metabolism, efficient respiratory and circulatory systems, lungs for gas exchange and a 4-chambered heart.

Question 37

Describe mammal reproduction.

Answer 37

Fertilization is internal, the embryo develops in the uterus. Offspring is born, not hatched. Nutrients diffuse through placenta (a membrane) into the embryo’s blood.

Question 38

Mammals have large _____ making them capable of _____.

Answer 38

Mammals have large brains making them capable of learning.

Question 39

Describe mammal feeding adaptations.

Answer 39

Mammals have feeding adaptations in the form of specialized teeth (we can determine the diet of a mammal by looking at its teeth).