Lecture 3- Diversity And Phylogeny Of Fishes

Question 1

What are the 2 vertebrate superclasses?

Answer 1

> Pisces (fishes)

> tetrapoda

Question 2

What are the classes of fishes?

Answer 2

> Agnatha
> acanthodii*
> placodermi*
> Chondrichthyes
> Osteichthyes 

• = extinct

Question 3

What classes of fishes are extinct?

Answer 3

> acanthodii

> placodermi

Question 4

List the subclasses and orders fish belonging to the class Agnatha

Answer 4

> class Agnatha
>>> subclass Ostracodermi
>>>>> order Heterostraci
>>>>> order Cephalaspidomorpha
>>>>> order Anapsida

> > > subclass Cyclostomata
» order Petromyzontiformes
» order Myxiniformes

Question 5

List the orders of the fishes belonging to the class Placodermi.

Answer 5

> class Placodermi
» order Arthrodira
» order Antiarchi

Question 6

List the subclasses and orders of the fishes belonging to the class Chondrichthyes

Answer 6

> class Chondrichthyes 
>>> subclass Elasmobranchii
>>>>> order Squaliformes
>>>>> order Rajiformes
>>>>> order Cladoselchii
>>>>> order Pleruacanthodii

>>> subclass Holocephali
>>>>> order Chimaeriformes

Question 7

List the subclasses of fishes belonging to the class Osteichthyes

Answer 7

> Class Osteichthyes 
>>> subclass Sarcopterygii
>>> subclass Actinopterygii

Question 8

Summarize the characteristics of the fishes belong to class Agnatha, subclass Ostracodermi

Answer 8

> oldest known vertebrates (450my)
all extinct
oldest were probably found in fresh or brackish water, but later ones may have been marine
Devonian period
lacked jaws and paired appendages
pharyngeal pumping mechanism (replaced the ciliary filter-feeding system of protochordates)
nasal openings
pineal organ
10 pairs of cranial nerves
dermal armor (protection and phosphate storage?)

Question 9

Summarize the fishes belonging to the class Agnatha, subclass Ostracodermi, order Heterostraci. Also provide an example.

Answer 9

> order Heterostraci
>>> armored head shield
>>> paired spines
>>> reversed heterocercal tail
>>> example:
>>>>> Pteraspis (

Question 10

Summarize the fishes belonging to the class Agnatha, subclass Ostracodermi, order Cephalaspidomorpha. Also provide an example.

Answer 10

> order Cephalaspidomorpha 
>>> bony head armor
>>> more flexible trunk armor
>>> mouth more anterior
>>> heterocercal tail
>>> bottom feeders
>>> example:
>>>>> Hemicyclaspis (

Question 11

Summarize the fishes belonging to the class Agnatha, subclass Ostracodermi, order Anapsida. Also provide an example.

Answer 11

> order Anapsida
>>> upper Silurian
>>> no large armor plates
>>> fusiform body shape
>>> some may have been open-water swimmers and more active predators
>>> example:
>>>>> Rhyncholepis (

Question 12

Summarize the characteristics fishes belonging to the class Agnatha, subclass Cyclostomata.

Answer 12

> characteristics
>>> lack jaws and paired appendages 
>>> two living orders:
>>>>> Petromyzontiformes
>>>>> Myxiniformes

Question 13

Summarize the fishes belonging to the class Agnatha, subclass Cyclostomatao, order Petromyzontiformes. Also provide an example.

Answer 13

> order Petromyzontiformes
» marine and freshwater lampreys
» example:
»» Petromyzon (»»» adults are predacious
»»» anadromous
»»» ammocoetes larva
»»»» filter feeder
»»» gills in pouches
»»»» separate gill openings
»»» median pineal gland
»»» single nostril does not open to pharynx
»»» adult lampreys spend most of their life in a marine environment
»»» adult lampreys return to freshwater to breed
»»» larval lampreys (ammocoetes larvae) grow and develop in the freshwater environments as filter feeders and then move into a marine environment to become predators
»»» this lifestyle is referred to as anadromous

Question 14

Describe the significance of each of the three major morphological developments in gnathostomes .

Answer 14

> DEVELOPMENT OF JAWS
» food ingested in morsels
» presence of stomach allows for storage of food
PAIRED APPENDAGES
»improved ability to pursue and/or escape
BUOYANCY MECHANISM
» evolved in the form of lungs and swim bladder
» fishes could control depth in water without having to swim continually
» note that sharks must swim to control depth and lack swim bladders

Question 15

List the characteristics of the fishes belonging to the class Acanthodii. Also, provide an example.

Answer 15

> characteristics
>>> streamlined body
>>> lack of large dermal scales
>>>>> ganoid type
>>> numerous paired and unpaired spines
>>> most were freshwater, but early forms were marine
> example:
>>> Climatius (

Question 16

List the characteristics of the fishes belonging to the class Placodemi, order Arthrodira. Also, provide an example.

Answer 16

> order Arthrodira
» characteristics
»» some were very large (up to 30ft in length)
»» movable joint between head shield and trunk
» example:
»» Coccosteus (»»» head and trunk armor
»»» streamlined body
»»» paired pectoral and pelvic fins
»»» active swimmers and predators

Question 17

List the characteristics of the fishes belonging to the class Placodemi, order Antiarchi. Also, provide an example.

Answer 17

> order Antiarchi 
>>> characteristics
>>>>> heavily armored
>>>>> small scale over caudal part of body
>>>>> triangular cross-section
>>>>> jointed pectoral spines
>>>>> bottom dweller
>>>>> heterocercal tail
>>> example:
>>>>> Pterichthyodes (

Question 18

List the characteristics of the fishes belonging to the class Chondrichthyes, subclass Elasmobranchii.

Answer 18

> characteristics
>>> large-holed eggs
>>> upper jaw is hyostolic 
>>> paired bobble nostrils
>>> gills open directly to exterior
>>> spiracle in some forms
>>> skeleton entirely of cartilage
>>> males possess claspers on pelvic fins to facilitate sperm transfer

Question 19

Sharks belong to what order of the class Chondrichthyes, subclass Elasmobranchii?

Answer 19

> order Squaliformes

Question 20

Skates and rays belong to what order of the class Chondrichthyes, subclass Elasmobranchii?

Answer 20

> order Rajiformes

Question 21

Summarize the characteristics of the fishes belonging to the class Chondrichthyes, subclass Elasmobranchii, order Cladoselchii. Also, provide an example.

Answer 21

> order Cladoselchii
>>> characteristics
>>>>> 3-6 feet in length
>>>>> shark-like
>>>>> extinct but thought to represent the first sharks
>>> example
>>>>> Cladodus (

Question 22

Summarize the characteristics of the fishes belonging to the class Chondrichthyes, subclass Elasmobranchii, order pleuracanthodii. Also, provide an example.

Answer 22

> order pleuracanthodii
>>> characteristics
>>>>> freshwater
>>>>> extinct
>>>>> diphycercal tail
>>> example:
>>>>> pleuracanthus (

Question 23

Summarize the characteristics of the fishes belonging to the class Chondrichthyes, subclass Elasmobranchii, order Chimaeriformes. Also, provide an example.

Answer 23

> order Chimaeriformes
>>> characteristics 
>>>>> fleshy operculum 
>>>>> claspers in males
>>>>> autostylic jaw articulation (adaptation for eating shellfish)
>>>>> lack scales over most of body
>>>>> lack spiracles
>>> example:
>>>>> Chimera (

Question 24

Summarize the characteristics of the fishes belonging to the class Osteichthyes, subclass Sarcopterygii. Also, provide an examples for the orders Crossopterygii and Dipnoi.

Answer 24

> subclass Sarcopterygii
» lobed paired fins
» internal Skelton is made of cartilage or bone, not spines
» orders
»» Crossopterygii
»»» Latimeria (»»» Osteolepis (»» Dipnoi
»»» Dipterus (

Question 25

Summarize the characteristics of the fishes belonging to the class Osteichthyes, subclass Actinopterygii. Also, provide an examples for the superorders Chondrostei, Holostei, and Teleostei.

Answer 25

``` > subclass Actinopterygii >>> Ray-finned fish >>> internal fin skeleton is made of spines >>> superorders >>>>> Chondrostei >>>>>>> sturgeons >>>>> Holostei >>>>>>> Amia (bowfins) >>>>> Teleostei >>>>>>> most freshwater and marine bony fishes ```

Question 26

True or False: transition from fins to feet is thought to have occurred approximately 370 million years ago?

Answer 26

> True >>> the debate as to which fish family made this move initially favored the coelacanth >>> prior to 1938 fossil coelacanths were known, but this group was thought to be extinct >>> fisherman off the Comora islands in the Indian Ocean actually caught a living coelacanth, now often referred to as a "living fossil." >>> many living examples of coelacanths have been caught since then >>> the bony structure of the coelacanth limb suggested to many biologists that this group was the ancestor of all tetrapods, and this became the predominant textbook dogma

Question 27

True or False: in 1977 researchers in Germany and Spain announced evidence that seemed to favor lungfishes as the sister group for tetrapods?

Answer 27

> true >>> Axel Myer and Rafael Zardoya used mitochondrial DNA analysis to demonstrate that the MtDNA of lungfish was closer to land animals such as frogs than that of coelacanths >>> S. Blair Hedges in 1993 also conducted similar studies that pointed to ancient lungfishes as ancestral tetrapods >>>>> lungfish traits such as external nostrils and modifications of the circulatory system and blood chemistry may also provide good clues as the ancestry of the earliest tetrapods >>> it is generally agreed that the rhipidistian said are the most likely group to represent the ancestral stock for tetrapods