Vertebrates

Question 1

Compare and contrast pharynx between vertebrate ancestor and amphioxus

Answer 1

feeding is no longer dependent on mucus, vertebrate ancestor engages in active feeding through a now muscularized pharynx. Respiratory tissue in the pharynx of vertebrates allows for diffusion of gases, and collagenous pharyngeal bars were replaced with bone/cartilage for added support and strength

Question 2

What are the synapomorphies for vertebrates?

Answer 2

muscularized pharynx, neural crest, cranium, tripartite brain, closed circulatory system, endoskeleton of cartilage or bone paired appendages, ectodermal placode

Question 3

what is the neural crest?

Answer 3

embryonic ectodermal tissue that gives rise to dentin, splanchnocranium (parts of the skull, jaw, gills), pigment cells, peripheral nerves, etc…

Question 4

what is the ectodermal placode?

Answer 4

thickening of the ectoderm that gives rise to sensory structures

Question 5

vertebrates active predacious lifestyle requires…

Answer 5

a sophisticated and cephalized nervous system

Question 6

How did the pharynx evolve in the jawless agnathans?

Answer 6

they evolved a muscular pumping pharynx, drawing in more food allowing for increased size and a more active lifestyle

Question 7

what were collagenous pharyngeal bars replaced with in vertebrates?

Answer 7

cartilaginous arches associated with capillary beds forming gills.

Question 8

what did the evolution of jaws allow vertebrates to do?

Answer 8

inhale or grasp prey

Question 9

what kind of scales did ostracoderms have?

Answer 9

dermal scales

Question 10

what kind of features did primitive ostracoderms have?

Answer 10

extensive head shields (large bony plates), hypoceral tail

Question 11

what kind of features did derived ostracoderms have?

Answer 11

pectoral fins, heterocercal tail, and partially ossified endoskeleton

Question 12

what purpose did pharyngeal gill pouches serve in ostracoderms?

Answer 12

multiple pharyngeal gill pouches exclusively for respiration, exposed as external gill openings

Question 13

What produced the dermal bony exoskeleton for ostracoderms?

Answer 13

the integuement

Question 14

what function do bones serve in ostracoderms?

Answer 14

support, protection, muscle attachment, and mineral reservoir

Question 15

hagfishes have __ semicircular canal(s)

Answer 15

1

Question 16

how many, andwhat function do barbels serve in hagfishes

Answer 16

3 to 4 pairs, they serve as mechanoreceptors

Question 17

what kind of circulatory system do hagfishes have?

Answer 17

a closed circulatory system with 4 hearts

Question 18

How many pairs of gill slits do lampreys have?

Answer 18

7 pairs of gill slits

Question 19

Lampreys have __ semicircular canal(s)

Answer 19

2

Question 20

What are the synapomorphies of Gnathostomes

Answer 20

jaws, dentin-based teeth, complex endoskeleton, 3 semicircular canals, paired fins/limbs, and gill tissue external to gill arches

Question 21

what structures did jaws evolve from?

Answer 21

2 pharyngeal arches: 1st arch became mandibular arch, 2nd arch becomes hyoid arch

Question 22

what is polydontism?

Answer 22

teeth form along infolding of epithelium (dental lamina) and advance anteriorly in a conveyor-belt fashion

Question 23

compare and contrast the physostomous and physostolic swimbladders

Answer 23

physostomous is connected to the alimentary tract, filled by gulping air and emptied by mouth belching. serving both buoyancy and respiratory functions allowing organism to live in hypoxic conditions. physostolic lacks a connected with the alimentary tract, addition and removal of gas is regulated by the circulatory system.